Merge pull request #9859 from jtattermusch/internal_ci_try_github

Add experimental CI job to run sanity tests
diff --git a/Makefile b/Makefile
index 0d8b960..0b0e127 100644
--- a/Makefile
+++ b/Makefile
@@ -2636,15 +2636,15 @@
 $(LIBDIR)/$(CONFIG)/gpr$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE): $(LIBGPR_OBJS)  $(ZLIB_DEP)
 	$(E) "[LD]      Linking $@"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(LD) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,--output-def=$(LIBDIR)/$(CONFIG)/gpr$(SHARED_VERSION_CORE).def -Wl,--out-implib=$(LIBDIR)/$(CONFIG)/libgpr$(SHARED_VERSION_CORE)-dll.a -o $(LIBDIR)/$(CONFIG)/gpr$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGPR_OBJS) $(LDLIBS) $(ZLIB_MERGE_LIBS)
+	$(Q) $(LD) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,--output-def=$(LIBDIR)/$(CONFIG)/gpr$(SHARED_VERSION_CORE).def -Wl,--out-implib=$(LIBDIR)/$(CONFIG)/libgpr$(SHARED_VERSION_CORE)-dll.a -o $(LIBDIR)/$(CONFIG)/gpr$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGPR_OBJS) $(ZLIB_MERGE_LIBS) $(LDLIBS)
 else
 $(LIBDIR)/$(CONFIG)/libgpr$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE): $(LIBGPR_OBJS)  $(ZLIB_DEP)
 	$(E) "[LD]      Linking $@"
 	$(Q) mkdir -p `dirname $@`
 ifeq ($(SYSTEM),Darwin)
-	$(Q) $(LD) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -install_name $(SHARED_PREFIX)gpr$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) -dynamiclib -o $(LIBDIR)/$(CONFIG)/libgpr$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGPR_OBJS) $(LDLIBS) $(ZLIB_MERGE_LIBS)
+	$(Q) $(LD) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -install_name $(SHARED_PREFIX)gpr$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) -dynamiclib -o $(LIBDIR)/$(CONFIG)/libgpr$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGPR_OBJS) $(ZLIB_MERGE_LIBS) $(LDLIBS)
 else
-	$(Q) $(LD) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,-soname,libgpr.so.3 -o $(LIBDIR)/$(CONFIG)/libgpr$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGPR_OBJS) $(LDLIBS) $(ZLIB_MERGE_LIBS)
+	$(Q) $(LD) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,-soname,libgpr.so.3 -o $(LIBDIR)/$(CONFIG)/libgpr$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGPR_OBJS) $(ZLIB_MERGE_LIBS) $(LDLIBS)
 	$(Q) ln -sf $(SHARED_PREFIX)gpr$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBDIR)/$(CONFIG)/libgpr$(SHARED_VERSION_CORE).so.3
 	$(Q) ln -sf $(SHARED_PREFIX)gpr$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBDIR)/$(CONFIG)/libgpr$(SHARED_VERSION_CORE).so
 endif
@@ -2969,15 +2969,15 @@
 $(LIBDIR)/$(CONFIG)/grpc$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE): $(LIBGRPC_OBJS)  $(ZLIB_DEP) $(LIBDIR)/$(CONFIG)/libgpr.a $(OPENSSL_DEP)
 	$(E) "[LD]      Linking $@"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(LD) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,--output-def=$(LIBDIR)/$(CONFIG)/grpc$(SHARED_VERSION_CORE).def -Wl,--out-implib=$(LIBDIR)/$(CONFIG)/libgrpc$(SHARED_VERSION_CORE)-dll.a -o $(LIBDIR)/$(CONFIG)/grpc$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGRPC_OBJS) $(LDLIBS) $(LIBDIR)/$(CONFIG)/libgpr.a $(OPENSSL_MERGE_LIBS) $(LDLIBS_SECURE) $(ZLIB_MERGE_LIBS)
+	$(Q) $(LD) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,--output-def=$(LIBDIR)/$(CONFIG)/grpc$(SHARED_VERSION_CORE).def -Wl,--out-implib=$(LIBDIR)/$(CONFIG)/libgrpc$(SHARED_VERSION_CORE)-dll.a -o $(LIBDIR)/$(CONFIG)/grpc$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGRPC_OBJS) $(LIBDIR)/$(CONFIG)/libgpr.a $(OPENSSL_MERGE_LIBS) $(LDLIBS_SECURE) $(ZLIB_MERGE_LIBS) $(LDLIBS)
 else
 $(LIBDIR)/$(CONFIG)/libgrpc$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE): $(LIBGRPC_OBJS)  $(ZLIB_DEP) $(LIBDIR)/$(CONFIG)/libgpr.a $(OPENSSL_DEP)
 	$(E) "[LD]      Linking $@"
 	$(Q) mkdir -p `dirname $@`
 ifeq ($(SYSTEM),Darwin)
-	$(Q) $(LD) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -install_name $(SHARED_PREFIX)grpc$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) -dynamiclib -o $(LIBDIR)/$(CONFIG)/libgrpc$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGRPC_OBJS) $(LDLIBS) $(LIBDIR)/$(CONFIG)/libgpr.a $(OPENSSL_MERGE_LIBS) $(LDLIBS_SECURE) $(ZLIB_MERGE_LIBS)
+	$(Q) $(LD) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -install_name $(SHARED_PREFIX)grpc$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) -dynamiclib -o $(LIBDIR)/$(CONFIG)/libgrpc$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGRPC_OBJS) $(LIBDIR)/$(CONFIG)/libgpr.a $(OPENSSL_MERGE_LIBS) $(LDLIBS_SECURE) $(ZLIB_MERGE_LIBS) $(LDLIBS)
 else
-	$(Q) $(LD) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,-soname,libgrpc.so.3 -o $(LIBDIR)/$(CONFIG)/libgrpc$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGRPC_OBJS) $(LDLIBS) $(LIBDIR)/$(CONFIG)/libgpr.a $(OPENSSL_MERGE_LIBS) $(LDLIBS_SECURE) $(ZLIB_MERGE_LIBS)
+	$(Q) $(LD) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,-soname,libgrpc.so.3 -o $(LIBDIR)/$(CONFIG)/libgrpc$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGRPC_OBJS) $(LIBDIR)/$(CONFIG)/libgpr.a $(OPENSSL_MERGE_LIBS) $(LDLIBS_SECURE) $(ZLIB_MERGE_LIBS) $(LDLIBS)
 	$(Q) ln -sf $(SHARED_PREFIX)grpc$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBDIR)/$(CONFIG)/libgrpc$(SHARED_VERSION_CORE).so.3
 	$(Q) ln -sf $(SHARED_PREFIX)grpc$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBDIR)/$(CONFIG)/libgrpc$(SHARED_VERSION_CORE).so
 endif
@@ -3251,15 +3251,15 @@
 $(LIBDIR)/$(CONFIG)/grpc_cronet$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE): $(LIBGRPC_CRONET_OBJS)  $(ZLIB_DEP) $(LIBDIR)/$(CONFIG)/libgpr.a $(OPENSSL_DEP)
 	$(E) "[LD]      Linking $@"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(LD) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,--output-def=$(LIBDIR)/$(CONFIG)/grpc_cronet$(SHARED_VERSION_CORE).def -Wl,--out-implib=$(LIBDIR)/$(CONFIG)/libgrpc_cronet$(SHARED_VERSION_CORE)-dll.a -o $(LIBDIR)/$(CONFIG)/grpc_cronet$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGRPC_CRONET_OBJS) $(LDLIBS) $(LIBDIR)/$(CONFIG)/libgpr.a $(OPENSSL_MERGE_LIBS) $(LDLIBS_SECURE) $(ZLIB_MERGE_LIBS)
+	$(Q) $(LD) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,--output-def=$(LIBDIR)/$(CONFIG)/grpc_cronet$(SHARED_VERSION_CORE).def -Wl,--out-implib=$(LIBDIR)/$(CONFIG)/libgrpc_cronet$(SHARED_VERSION_CORE)-dll.a -o $(LIBDIR)/$(CONFIG)/grpc_cronet$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGRPC_CRONET_OBJS) $(LIBDIR)/$(CONFIG)/libgpr.a $(OPENSSL_MERGE_LIBS) $(LDLIBS_SECURE) $(ZLIB_MERGE_LIBS) $(LDLIBS)
 else
 $(LIBDIR)/$(CONFIG)/libgrpc_cronet$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE): $(LIBGRPC_CRONET_OBJS)  $(ZLIB_DEP) $(LIBDIR)/$(CONFIG)/libgpr.a $(OPENSSL_DEP)
 	$(E) "[LD]      Linking $@"
 	$(Q) mkdir -p `dirname $@`
 ifeq ($(SYSTEM),Darwin)
-	$(Q) $(LD) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -install_name $(SHARED_PREFIX)grpc_cronet$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) -dynamiclib -o $(LIBDIR)/$(CONFIG)/libgrpc_cronet$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGRPC_CRONET_OBJS) $(LDLIBS) $(LIBDIR)/$(CONFIG)/libgpr.a $(OPENSSL_MERGE_LIBS) $(LDLIBS_SECURE) $(ZLIB_MERGE_LIBS)
+	$(Q) $(LD) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -install_name $(SHARED_PREFIX)grpc_cronet$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) -dynamiclib -o $(LIBDIR)/$(CONFIG)/libgrpc_cronet$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGRPC_CRONET_OBJS) $(LIBDIR)/$(CONFIG)/libgpr.a $(OPENSSL_MERGE_LIBS) $(LDLIBS_SECURE) $(ZLIB_MERGE_LIBS) $(LDLIBS)
 else
-	$(Q) $(LD) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,-soname,libgrpc_cronet.so.3 -o $(LIBDIR)/$(CONFIG)/libgrpc_cronet$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGRPC_CRONET_OBJS) $(LDLIBS) $(LIBDIR)/$(CONFIG)/libgpr.a $(OPENSSL_MERGE_LIBS) $(LDLIBS_SECURE) $(ZLIB_MERGE_LIBS)
+	$(Q) $(LD) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,-soname,libgrpc_cronet.so.3 -o $(LIBDIR)/$(CONFIG)/libgrpc_cronet$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGRPC_CRONET_OBJS) $(LIBDIR)/$(CONFIG)/libgpr.a $(OPENSSL_MERGE_LIBS) $(LDLIBS_SECURE) $(ZLIB_MERGE_LIBS) $(LDLIBS)
 	$(Q) ln -sf $(SHARED_PREFIX)grpc_cronet$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBDIR)/$(CONFIG)/libgrpc_cronet$(SHARED_VERSION_CORE).so.3
 	$(Q) ln -sf $(SHARED_PREFIX)grpc_cronet$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBDIR)/$(CONFIG)/libgrpc_cronet$(SHARED_VERSION_CORE).so
 endif
@@ -3770,15 +3770,15 @@
 $(LIBDIR)/$(CONFIG)/grpc_unsecure$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE): $(LIBGRPC_UNSECURE_OBJS)  $(ZLIB_DEP) $(LIBDIR)/$(CONFIG)/libgpr.a
 	$(E) "[LD]      Linking $@"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(LD) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,--output-def=$(LIBDIR)/$(CONFIG)/grpc_unsecure$(SHARED_VERSION_CORE).def -Wl,--out-implib=$(LIBDIR)/$(CONFIG)/libgrpc_unsecure$(SHARED_VERSION_CORE)-dll.a -o $(LIBDIR)/$(CONFIG)/grpc_unsecure$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGRPC_UNSECURE_OBJS) $(LDLIBS) $(LIBDIR)/$(CONFIG)/libgpr.a $(ZLIB_MERGE_LIBS)
+	$(Q) $(LD) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,--output-def=$(LIBDIR)/$(CONFIG)/grpc_unsecure$(SHARED_VERSION_CORE).def -Wl,--out-implib=$(LIBDIR)/$(CONFIG)/libgrpc_unsecure$(SHARED_VERSION_CORE)-dll.a -o $(LIBDIR)/$(CONFIG)/grpc_unsecure$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGRPC_UNSECURE_OBJS) $(LIBDIR)/$(CONFIG)/libgpr.a $(ZLIB_MERGE_LIBS) $(LDLIBS)
 else
 $(LIBDIR)/$(CONFIG)/libgrpc_unsecure$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE): $(LIBGRPC_UNSECURE_OBJS)  $(ZLIB_DEP) $(LIBDIR)/$(CONFIG)/libgpr.a
 	$(E) "[LD]      Linking $@"
 	$(Q) mkdir -p `dirname $@`
 ifeq ($(SYSTEM),Darwin)
-	$(Q) $(LD) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -install_name $(SHARED_PREFIX)grpc_unsecure$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) -dynamiclib -o $(LIBDIR)/$(CONFIG)/libgrpc_unsecure$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGRPC_UNSECURE_OBJS) $(LDLIBS) $(LIBDIR)/$(CONFIG)/libgpr.a $(ZLIB_MERGE_LIBS)
+	$(Q) $(LD) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -install_name $(SHARED_PREFIX)grpc_unsecure$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) -dynamiclib -o $(LIBDIR)/$(CONFIG)/libgrpc_unsecure$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGRPC_UNSECURE_OBJS) $(LIBDIR)/$(CONFIG)/libgpr.a $(ZLIB_MERGE_LIBS) $(LDLIBS)
 else
-	$(Q) $(LD) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,-soname,libgrpc_unsecure.so.3 -o $(LIBDIR)/$(CONFIG)/libgrpc_unsecure$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGRPC_UNSECURE_OBJS) $(LDLIBS) $(LIBDIR)/$(CONFIG)/libgpr.a $(ZLIB_MERGE_LIBS)
+	$(Q) $(LD) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,-soname,libgrpc_unsecure.so.3 -o $(LIBDIR)/$(CONFIG)/libgrpc_unsecure$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBGRPC_UNSECURE_OBJS) $(LIBDIR)/$(CONFIG)/libgpr.a $(ZLIB_MERGE_LIBS) $(LDLIBS)
 	$(Q) ln -sf $(SHARED_PREFIX)grpc_unsecure$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBDIR)/$(CONFIG)/libgrpc_unsecure$(SHARED_VERSION_CORE).so.3
 	$(Q) ln -sf $(SHARED_PREFIX)grpc_unsecure$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBDIR)/$(CONFIG)/libgrpc_unsecure$(SHARED_VERSION_CORE).so
 endif
@@ -4045,15 +4045,15 @@
 $(LIBDIR)/$(CONFIG)/grpc++$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP): $(LIBGRPC++_OBJS)  $(ZLIB_DEP) $(PROTOBUF_DEP) $(LIBDIR)/$(CONFIG)/grpc$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(OPENSSL_DEP)
 	$(E) "[LD]      Linking $@"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,--output-def=$(LIBDIR)/$(CONFIG)/grpc++$(SHARED_VERSION_CPP).def -Wl,--out-implib=$(LIBDIR)/$(CONFIG)/libgrpc++$(SHARED_VERSION_CPP)-dll.a -o $(LIBDIR)/$(CONFIG)/grpc++$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) $(LIBGRPC++_OBJS) $(LDLIBS) $(ZLIB_MERGE_LIBS) $(LDLIBSXX) $(LDLIBS_PROTOBUF) -lgrpc$(SHARED_VERSION_CORE)-dll
+	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,--output-def=$(LIBDIR)/$(CONFIG)/grpc++$(SHARED_VERSION_CPP).def -Wl,--out-implib=$(LIBDIR)/$(CONFIG)/libgrpc++$(SHARED_VERSION_CPP)-dll.a -o $(LIBDIR)/$(CONFIG)/grpc++$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) $(LIBGRPC++_OBJS) $(ZLIB_MERGE_LIBS) $(LDLIBSXX) $(LDLIBS_PROTOBUF) $(LDLIBS) -lgrpc$(SHARED_VERSION_CORE)-dll
 else
 $(LIBDIR)/$(CONFIG)/libgrpc++$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP): $(LIBGRPC++_OBJS)  $(ZLIB_DEP) $(PROTOBUF_DEP) $(LIBDIR)/$(CONFIG)/libgrpc.$(SHARED_EXT_CORE) $(OPENSSL_DEP)
 	$(E) "[LD]      Linking $@"
 	$(Q) mkdir -p `dirname $@`
 ifeq ($(SYSTEM),Darwin)
-	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -install_name $(SHARED_PREFIX)grpc++$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) -dynamiclib -o $(LIBDIR)/$(CONFIG)/libgrpc++$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) $(LIBGRPC++_OBJS) $(LDLIBS) $(ZLIB_MERGE_LIBS) $(LDLIBSXX) $(LDLIBS_PROTOBUF) -lgrpc
+	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -install_name $(SHARED_PREFIX)grpc++$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) -dynamiclib -o $(LIBDIR)/$(CONFIG)/libgrpc++$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) $(LIBGRPC++_OBJS) $(ZLIB_MERGE_LIBS) $(LDLIBSXX) $(LDLIBS_PROTOBUF) $(LDLIBS) -lgrpc
 else
-	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,-soname,libgrpc++.so.3 -o $(LIBDIR)/$(CONFIG)/libgrpc++$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) $(LIBGRPC++_OBJS) $(LDLIBS) $(ZLIB_MERGE_LIBS) $(LDLIBSXX) $(LDLIBS_PROTOBUF) -lgrpc
+	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,-soname,libgrpc++.so.3 -o $(LIBDIR)/$(CONFIG)/libgrpc++$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) $(LIBGRPC++_OBJS) $(ZLIB_MERGE_LIBS) $(LDLIBSXX) $(LDLIBS_PROTOBUF) $(LDLIBS) -lgrpc
 	$(Q) ln -sf $(SHARED_PREFIX)grpc++$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) $(LIBDIR)/$(CONFIG)/libgrpc++$(SHARED_VERSION_CPP).so.1
 	$(Q) ln -sf $(SHARED_PREFIX)grpc++$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) $(LIBDIR)/$(CONFIG)/libgrpc++$(SHARED_VERSION_CPP).so
 endif
@@ -4436,15 +4436,15 @@
 $(LIBDIR)/$(CONFIG)/grpc++_cronet$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP): $(LIBGRPC++_CRONET_OBJS)  $(ZLIB_DEP) $(PROTOBUF_DEP) $(LIBDIR)/$(CONFIG)/gpr$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBDIR)/$(CONFIG)/grpc_cronet$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(OPENSSL_DEP)
 	$(E) "[LD]      Linking $@"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,--output-def=$(LIBDIR)/$(CONFIG)/grpc++_cronet$(SHARED_VERSION_CPP).def -Wl,--out-implib=$(LIBDIR)/$(CONFIG)/libgrpc++_cronet$(SHARED_VERSION_CPP)-dll.a -o $(LIBDIR)/$(CONFIG)/grpc++_cronet$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) $(LIBGRPC++_CRONET_OBJS) $(LDLIBS) $(OPENSSL_MERGE_LIBS) $(LDLIBS_SECURE) $(ZLIB_MERGE_LIBS) $(LDLIBSXX) $(LDLIBS_PROTOBUF) -lgpr$(SHARED_VERSION_CORE)-dll -lgrpc_cronet$(SHARED_VERSION_CORE)-dll
+	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,--output-def=$(LIBDIR)/$(CONFIG)/grpc++_cronet$(SHARED_VERSION_CPP).def -Wl,--out-implib=$(LIBDIR)/$(CONFIG)/libgrpc++_cronet$(SHARED_VERSION_CPP)-dll.a -o $(LIBDIR)/$(CONFIG)/grpc++_cronet$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) $(LIBGRPC++_CRONET_OBJS) $(OPENSSL_MERGE_LIBS) $(LDLIBS_SECURE) $(ZLIB_MERGE_LIBS) $(LDLIBSXX) $(LDLIBS_PROTOBUF) $(LDLIBS) -lgpr$(SHARED_VERSION_CORE)-dll -lgrpc_cronet$(SHARED_VERSION_CORE)-dll
 else
 $(LIBDIR)/$(CONFIG)/libgrpc++_cronet$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP): $(LIBGRPC++_CRONET_OBJS)  $(ZLIB_DEP) $(PROTOBUF_DEP) $(LIBDIR)/$(CONFIG)/libgpr.$(SHARED_EXT_CORE) $(LIBDIR)/$(CONFIG)/libgrpc_cronet.$(SHARED_EXT_CORE) $(OPENSSL_DEP)
 	$(E) "[LD]      Linking $@"
 	$(Q) mkdir -p `dirname $@`
 ifeq ($(SYSTEM),Darwin)
-	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -install_name $(SHARED_PREFIX)grpc++_cronet$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) -dynamiclib -o $(LIBDIR)/$(CONFIG)/libgrpc++_cronet$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) $(LIBGRPC++_CRONET_OBJS) $(LDLIBS) $(OPENSSL_MERGE_LIBS) $(LDLIBS_SECURE) $(ZLIB_MERGE_LIBS) $(LDLIBSXX) $(LDLIBS_PROTOBUF) -lgpr -lgrpc_cronet
+	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -install_name $(SHARED_PREFIX)grpc++_cronet$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) -dynamiclib -o $(LIBDIR)/$(CONFIG)/libgrpc++_cronet$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) $(LIBGRPC++_CRONET_OBJS) $(OPENSSL_MERGE_LIBS) $(LDLIBS_SECURE) $(ZLIB_MERGE_LIBS) $(LDLIBSXX) $(LDLIBS_PROTOBUF) $(LDLIBS) -lgpr -lgrpc_cronet
 else
-	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,-soname,libgrpc++_cronet.so.3 -o $(LIBDIR)/$(CONFIG)/libgrpc++_cronet$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) $(LIBGRPC++_CRONET_OBJS) $(LDLIBS) $(OPENSSL_MERGE_LIBS) $(LDLIBS_SECURE) $(ZLIB_MERGE_LIBS) $(LDLIBSXX) $(LDLIBS_PROTOBUF) -lgpr -lgrpc_cronet
+	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,-soname,libgrpc++_cronet.so.3 -o $(LIBDIR)/$(CONFIG)/libgrpc++_cronet$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) $(LIBGRPC++_CRONET_OBJS) $(OPENSSL_MERGE_LIBS) $(LDLIBS_SECURE) $(ZLIB_MERGE_LIBS) $(LDLIBSXX) $(LDLIBS_PROTOBUF) $(LDLIBS) -lgpr -lgrpc_cronet
 	$(Q) ln -sf $(SHARED_PREFIX)grpc++_cronet$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) $(LIBDIR)/$(CONFIG)/libgrpc++_cronet$(SHARED_VERSION_CPP).so.1
 	$(Q) ln -sf $(SHARED_PREFIX)grpc++_cronet$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) $(LIBDIR)/$(CONFIG)/libgrpc++_cronet$(SHARED_VERSION_CPP).so
 endif
@@ -4559,15 +4559,15 @@
 $(LIBDIR)/$(CONFIG)/grpc++_reflection$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP): $(LIBGRPC++_REFLECTION_OBJS)  $(ZLIB_DEP) $(PROTOBUF_DEP) $(LIBDIR)/$(CONFIG)/grpc++$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) $(OPENSSL_DEP)
 	$(E) "[LD]      Linking $@"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,--output-def=$(LIBDIR)/$(CONFIG)/grpc++_reflection$(SHARED_VERSION_CPP).def -Wl,--out-implib=$(LIBDIR)/$(CONFIG)/libgrpc++_reflection$(SHARED_VERSION_CPP)-dll.a -o $(LIBDIR)/$(CONFIG)/grpc++_reflection$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) $(LIBGRPC++_REFLECTION_OBJS) $(LDLIBS) $(ZLIB_MERGE_LIBS) $(LDLIBSXX) $(LDLIBS_PROTOBUF) -lgrpc++$(SHARED_VERSION_CPP)-dll
+	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,--output-def=$(LIBDIR)/$(CONFIG)/grpc++_reflection$(SHARED_VERSION_CPP).def -Wl,--out-implib=$(LIBDIR)/$(CONFIG)/libgrpc++_reflection$(SHARED_VERSION_CPP)-dll.a -o $(LIBDIR)/$(CONFIG)/grpc++_reflection$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) $(LIBGRPC++_REFLECTION_OBJS) $(ZLIB_MERGE_LIBS) $(LDLIBSXX) $(LDLIBS_PROTOBUF) $(LDLIBS) -lgrpc++$(SHARED_VERSION_CPP)-dll
 else
 $(LIBDIR)/$(CONFIG)/libgrpc++_reflection$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP): $(LIBGRPC++_REFLECTION_OBJS)  $(ZLIB_DEP) $(PROTOBUF_DEP) $(LIBDIR)/$(CONFIG)/libgrpc++.$(SHARED_EXT_CPP) $(OPENSSL_DEP)
 	$(E) "[LD]      Linking $@"
 	$(Q) mkdir -p `dirname $@`
 ifeq ($(SYSTEM),Darwin)
-	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -install_name $(SHARED_PREFIX)grpc++_reflection$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) -dynamiclib -o $(LIBDIR)/$(CONFIG)/libgrpc++_reflection$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) $(LIBGRPC++_REFLECTION_OBJS) $(LDLIBS) $(ZLIB_MERGE_LIBS) $(LDLIBSXX) $(LDLIBS_PROTOBUF) -lgrpc++
+	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -install_name $(SHARED_PREFIX)grpc++_reflection$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) -dynamiclib -o $(LIBDIR)/$(CONFIG)/libgrpc++_reflection$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) $(LIBGRPC++_REFLECTION_OBJS) $(ZLIB_MERGE_LIBS) $(LDLIBSXX) $(LDLIBS_PROTOBUF) $(LDLIBS) -lgrpc++
 else
-	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,-soname,libgrpc++_reflection.so.3 -o $(LIBDIR)/$(CONFIG)/libgrpc++_reflection$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) $(LIBGRPC++_REFLECTION_OBJS) $(LDLIBS) $(ZLIB_MERGE_LIBS) $(LDLIBSXX) $(LDLIBS_PROTOBUF) -lgrpc++
+	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,-soname,libgrpc++_reflection.so.3 -o $(LIBDIR)/$(CONFIG)/libgrpc++_reflection$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) $(LIBGRPC++_REFLECTION_OBJS) $(ZLIB_MERGE_LIBS) $(LDLIBSXX) $(LDLIBS_PROTOBUF) $(LDLIBS) -lgrpc++
 	$(Q) ln -sf $(SHARED_PREFIX)grpc++_reflection$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) $(LIBDIR)/$(CONFIG)/libgrpc++_reflection$(SHARED_VERSION_CPP).so.1
 	$(Q) ln -sf $(SHARED_PREFIX)grpc++_reflection$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) $(LIBDIR)/$(CONFIG)/libgrpc++_reflection$(SHARED_VERSION_CPP).so
 endif
@@ -4915,15 +4915,15 @@
 $(LIBDIR)/$(CONFIG)/grpc++_unsecure$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP): $(LIBGRPC++_UNSECURE_OBJS)  $(ZLIB_DEP) $(PROTOBUF_DEP) $(LIBDIR)/$(CONFIG)/gpr$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE) $(LIBDIR)/$(CONFIG)/grpc_unsecure$(SHARED_VERSION_CORE).$(SHARED_EXT_CORE)
 	$(E) "[LD]      Linking $@"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,--output-def=$(LIBDIR)/$(CONFIG)/grpc++_unsecure$(SHARED_VERSION_CPP).def -Wl,--out-implib=$(LIBDIR)/$(CONFIG)/libgrpc++_unsecure$(SHARED_VERSION_CPP)-dll.a -o $(LIBDIR)/$(CONFIG)/grpc++_unsecure$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) $(LIBGRPC++_UNSECURE_OBJS) $(LDLIBS) $(ZLIB_MERGE_LIBS) $(LDLIBSXX) $(LDLIBS_PROTOBUF) -lgpr$(SHARED_VERSION_CORE)-dll -lgrpc_unsecure$(SHARED_VERSION_CORE)-dll
+	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,--output-def=$(LIBDIR)/$(CONFIG)/grpc++_unsecure$(SHARED_VERSION_CPP).def -Wl,--out-implib=$(LIBDIR)/$(CONFIG)/libgrpc++_unsecure$(SHARED_VERSION_CPP)-dll.a -o $(LIBDIR)/$(CONFIG)/grpc++_unsecure$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) $(LIBGRPC++_UNSECURE_OBJS) $(ZLIB_MERGE_LIBS) $(LDLIBSXX) $(LDLIBS_PROTOBUF) $(LDLIBS) -lgpr$(SHARED_VERSION_CORE)-dll -lgrpc_unsecure$(SHARED_VERSION_CORE)-dll
 else
 $(LIBDIR)/$(CONFIG)/libgrpc++_unsecure$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP): $(LIBGRPC++_UNSECURE_OBJS)  $(ZLIB_DEP) $(PROTOBUF_DEP) $(LIBDIR)/$(CONFIG)/libgpr.$(SHARED_EXT_CORE) $(LIBDIR)/$(CONFIG)/libgrpc_unsecure.$(SHARED_EXT_CORE)
 	$(E) "[LD]      Linking $@"
 	$(Q) mkdir -p `dirname $@`
 ifeq ($(SYSTEM),Darwin)
-	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -install_name $(SHARED_PREFIX)grpc++_unsecure$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) -dynamiclib -o $(LIBDIR)/$(CONFIG)/libgrpc++_unsecure$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) $(LIBGRPC++_UNSECURE_OBJS) $(LDLIBS) $(ZLIB_MERGE_LIBS) $(LDLIBSXX) $(LDLIBS_PROTOBUF) -lgpr -lgrpc_unsecure
+	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -install_name $(SHARED_PREFIX)grpc++_unsecure$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) -dynamiclib -o $(LIBDIR)/$(CONFIG)/libgrpc++_unsecure$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) $(LIBGRPC++_UNSECURE_OBJS) $(ZLIB_MERGE_LIBS) $(LDLIBSXX) $(LDLIBS_PROTOBUF) $(LDLIBS) -lgpr -lgrpc_unsecure
 else
-	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,-soname,libgrpc++_unsecure.so.3 -o $(LIBDIR)/$(CONFIG)/libgrpc++_unsecure$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) $(LIBGRPC++_UNSECURE_OBJS) $(LDLIBS) $(ZLIB_MERGE_LIBS) $(LDLIBSXX) $(LDLIBS_PROTOBUF) -lgpr -lgrpc_unsecure
+	$(Q) $(LDXX) $(LDFLAGS) -L$(LIBDIR)/$(CONFIG) -shared -Wl,-soname,libgrpc++_unsecure.so.3 -o $(LIBDIR)/$(CONFIG)/libgrpc++_unsecure$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) $(LIBGRPC++_UNSECURE_OBJS) $(ZLIB_MERGE_LIBS) $(LDLIBSXX) $(LDLIBS_PROTOBUF) $(LDLIBS) -lgpr -lgrpc_unsecure
 	$(Q) ln -sf $(SHARED_PREFIX)grpc++_unsecure$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) $(LIBDIR)/$(CONFIG)/libgrpc++_unsecure$(SHARED_VERSION_CPP).so.1
 	$(Q) ln -sf $(SHARED_PREFIX)grpc++_unsecure$(SHARED_VERSION_CPP).$(SHARED_EXT_CPP) $(LIBDIR)/$(CONFIG)/libgrpc++_unsecure$(SHARED_VERSION_CPP).so
 endif
@@ -5456,15 +5456,15 @@
 $(LIBDIR)/$(CONFIG)/grpc_csharp_ext$(SHARED_VERSION_CSHARP).$(SHARED_EXT_CSHARP): $(LIBGRPC_CSHARP_EXT_OBJS)  $(ZLIB_DEP) $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr.a $(OPENSSL_DEP)
 	$(E) "[LD]      Linking $@"
 	$(Q) mkdir -p `dirname $@`
-	$(Q) $(LD) $(LDFLAGS) $(if $(subst Linux,,$(SYSTEM)),,-Wl$(comma)-wrap$(comma)memcpy) -L$(LIBDIR)/$(CONFIG) -shared -Wl,--output-def=$(LIBDIR)/$(CONFIG)/grpc_csharp_ext$(SHARED_VERSION_CSHARP).def -Wl,--out-implib=$(LIBDIR)/$(CONFIG)/libgrpc_csharp_ext$(SHARED_VERSION_CSHARP)-dll.a -o $(LIBDIR)/$(CONFIG)/grpc_csharp_ext$(SHARED_VERSION_CSHARP).$(SHARED_EXT_CSHARP) $(LIBGRPC_CSHARP_EXT_OBJS) $(LDLIBS) $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr.a $(ZLIB_MERGE_LIBS)
+	$(Q) $(LD) $(LDFLAGS) $(if $(subst Linux,,$(SYSTEM)),,-Wl$(comma)-wrap$(comma)memcpy) -L$(LIBDIR)/$(CONFIG) -shared -Wl,--output-def=$(LIBDIR)/$(CONFIG)/grpc_csharp_ext$(SHARED_VERSION_CSHARP).def -Wl,--out-implib=$(LIBDIR)/$(CONFIG)/libgrpc_csharp_ext$(SHARED_VERSION_CSHARP)-dll.a -o $(LIBDIR)/$(CONFIG)/grpc_csharp_ext$(SHARED_VERSION_CSHARP).$(SHARED_EXT_CSHARP) $(LIBGRPC_CSHARP_EXT_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr.a $(ZLIB_MERGE_LIBS) $(LDLIBS)
 else
 $(LIBDIR)/$(CONFIG)/libgrpc_csharp_ext$(SHARED_VERSION_CSHARP).$(SHARED_EXT_CSHARP): $(LIBGRPC_CSHARP_EXT_OBJS)  $(ZLIB_DEP) $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr.a $(OPENSSL_DEP)
 	$(E) "[LD]      Linking $@"
 	$(Q) mkdir -p `dirname $@`
 ifeq ($(SYSTEM),Darwin)
-	$(Q) $(LD) $(LDFLAGS) $(if $(subst Linux,,$(SYSTEM)),,-Wl$(comma)-wrap$(comma)memcpy) -L$(LIBDIR)/$(CONFIG) -install_name $(SHARED_PREFIX)grpc_csharp_ext$(SHARED_VERSION_CSHARP).$(SHARED_EXT_CSHARP) -dynamiclib -o $(LIBDIR)/$(CONFIG)/libgrpc_csharp_ext$(SHARED_VERSION_CSHARP).$(SHARED_EXT_CSHARP) $(LIBGRPC_CSHARP_EXT_OBJS) $(LDLIBS) $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr.a $(ZLIB_MERGE_LIBS)
+	$(Q) $(LD) $(LDFLAGS) $(if $(subst Linux,,$(SYSTEM)),,-Wl$(comma)-wrap$(comma)memcpy) -L$(LIBDIR)/$(CONFIG) -install_name $(SHARED_PREFIX)grpc_csharp_ext$(SHARED_VERSION_CSHARP).$(SHARED_EXT_CSHARP) -dynamiclib -o $(LIBDIR)/$(CONFIG)/libgrpc_csharp_ext$(SHARED_VERSION_CSHARP).$(SHARED_EXT_CSHARP) $(LIBGRPC_CSHARP_EXT_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr.a $(ZLIB_MERGE_LIBS) $(LDLIBS)
 else
-	$(Q) $(LD) $(LDFLAGS) $(if $(subst Linux,,$(SYSTEM)),,-Wl$(comma)-wrap$(comma)memcpy) -L$(LIBDIR)/$(CONFIG) -shared -Wl,-soname,libgrpc_csharp_ext.so.3 -o $(LIBDIR)/$(CONFIG)/libgrpc_csharp_ext$(SHARED_VERSION_CSHARP).$(SHARED_EXT_CSHARP) $(LIBGRPC_CSHARP_EXT_OBJS) $(LDLIBS) $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr.a $(ZLIB_MERGE_LIBS)
+	$(Q) $(LD) $(LDFLAGS) $(if $(subst Linux,,$(SYSTEM)),,-Wl$(comma)-wrap$(comma)memcpy) -L$(LIBDIR)/$(CONFIG) -shared -Wl,-soname,libgrpc_csharp_ext.so.3 -o $(LIBDIR)/$(CONFIG)/libgrpc_csharp_ext$(SHARED_VERSION_CSHARP).$(SHARED_EXT_CSHARP) $(LIBGRPC_CSHARP_EXT_OBJS) $(LIBDIR)/$(CONFIG)/libgrpc.a $(LIBDIR)/$(CONFIG)/libgpr.a $(ZLIB_MERGE_LIBS) $(LDLIBS)
 	$(Q) ln -sf $(SHARED_PREFIX)grpc_csharp_ext$(SHARED_VERSION_CSHARP).$(SHARED_EXT_CSHARP) $(LIBDIR)/$(CONFIG)/libgrpc_csharp_ext$(SHARED_VERSION_CSHARP).so.1
 	$(Q) ln -sf $(SHARED_PREFIX)grpc_csharp_ext$(SHARED_VERSION_CSHARP).$(SHARED_EXT_CSHARP) $(LIBDIR)/$(CONFIG)/libgrpc_csharp_ext$(SHARED_VERSION_CSHARP).so
 endif
diff --git a/Rakefile b/Rakefile
index c8bca20..12ac127 100755
--- a/Rakefile
+++ b/Rakefile
@@ -93,7 +93,7 @@
   [ w64, w32 ].each do |opt|
     env_comp = "CC=#{opt[:cross]}-gcc "
     env_comp += "LD=#{opt[:cross]}-gcc "
-    docker_for_windows "#{env} #{env_comp} make -j #{out} && #{opt[:cross]}-strip -x -S #{out} && cp #{out} #{opt[:out]}"
+    docker_for_windows "gem update --system && #{env} #{env_comp} make -j #{out} && #{opt[:cross]}-strip -x -S #{out} && cp #{out} #{opt[:out]}"
   end
 
 end
@@ -107,10 +107,10 @@
   if RUBY_PLATFORM =~ /darwin/
     FileUtils.touch 'grpc_c.32.ruby'
     FileUtils.touch 'grpc_c.64.ruby'
-    system "rake cross native gem RUBY_CC_VERSION=2.3.0:2.2.2:2.1.5:2.0.0 V=#{verbose} GRPC_CONFIG=#{grpc_config}"
+    system "rake cross native gem RUBY_CC_VERSION=2.4.0:2.3.0:2.2.2:2.1.5:2.0.0 V=#{verbose} GRPC_CONFIG=#{grpc_config}"
   else
     Rake::Task['dlls'].execute
-    docker_for_windows "bundle && rake cross native gem RUBY_CC_VERSION=2.3.0:2.2.2:2.1.5:2.0.0 V=#{verbose} GRPC_CONFIG=#{grpc_config}"
+    docker_for_windows "gem update --system && bundle && rake cross native gem RUBY_CC_VERSION=2.4.0:2.3.0:2.2.2:2.1.5:2.0.0 V=#{verbose} GRPC_CONFIG=#{grpc_config}"
   end
 end
 
diff --git a/binding.gyp b/binding.gyp
index 8ff3d8c..7190082 100644
--- a/binding.gyp
+++ b/binding.gyp
@@ -51,7 +51,9 @@
     'conditions': [
       ['runtime=="node"', {
         'defines': [
-          'GRPC_UV'
+          # Disabling this while bugs are ironed out. Uncomment this to
+          # re-enable libuv integration in C core.
+          # 'GRPC_UV'
         ]
       }],
       ['OS!="win" and runtime=="electron"', {
diff --git a/examples/ruby/grpc-demo.gemspec b/examples/ruby/grpc-demo.gemspec
index e1b77a5..4423fd3 100644
--- a/examples/ruby/grpc-demo.gemspec
+++ b/examples/ruby/grpc-demo.gemspec
@@ -17,7 +17,7 @@
   s.require_paths = ['lib']
   s.platform      = Gem::Platform::RUBY
 
-  s.add_dependency 'grpc', '~> 1.0.0'
+  s.add_dependency 'grpc', '~> 1.0'
 
   s.add_development_dependency 'bundler', '~> 1.7'
 end
diff --git a/examples/ruby/without_protobuf/README.md b/examples/ruby/without_protobuf/README.md
new file mode 100644
index 0000000..f961164
--- /dev/null
+++ b/examples/ruby/without_protobuf/README.md
@@ -0,0 +1,6 @@
+gRPC (Ruby) without protobuf
+========================
+
+This directory contains a simple example of using gRPC without protobuf.
+
+This is mainly intended to show basic usage of the GRPC::GenericService module
diff --git a/examples/ruby/without_protobuf/echo_client.rb b/examples/ruby/without_protobuf/echo_client.rb
new file mode 100755
index 0000000..4a7b92a
--- /dev/null
+++ b/examples/ruby/without_protobuf/echo_client.rb
@@ -0,0 +1,49 @@
+#!/usr/bin/env ruby
+
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+# Sample app that connects to a 'EchoWithoutProtobuf' service.
+#
+# Usage: $ path/to/echo_client.rb
+
+this_dir = File.expand_path(File.dirname(__FILE__))
+$LOAD_PATH.unshift(this_dir) unless $LOAD_PATH.include?(this_dir)
+
+require 'grpc'
+require 'echo_services_noprotobuf'
+
+def main
+  stub = EchoWithoutProtobuf::Stub.new('localhost:50051', :this_channel_is_insecure)
+  user = ARGV.size > 0 ?  ARGV[0] : 'world'
+  message = stub.echo("hello #{user}")
+  p "Reponse: #{message}"
+end
+
+main
diff --git a/examples/ruby/without_protobuf/echo_server.rb b/examples/ruby/without_protobuf/echo_server.rb
new file mode 100755
index 0000000..e60f684
--- /dev/null
+++ b/examples/ruby/without_protobuf/echo_server.rb
@@ -0,0 +1,59 @@
+#!/usr/bin/env ruby
+
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+# Sample gRPC server that implements the EchoWithoutProtobuf service.
+#
+# Usage: $ path/to/echo_server.rb
+
+this_dir = File.expand_path(File.dirname(__FILE__))
+$LOAD_PATH.unshift(this_dir) unless $LOAD_PATH.include?(this_dir)
+
+require 'grpc'
+require 'echo_services_noprotobuf'
+
+# EchoServer is simple server that implements the EchoWithoutProtobuf server.
+class EchoServer < EchoWithoutProtobuf::Service
+  # echo implements the EchoWithoutProtobuf 'Echo' rpc method.
+  def echo(echo_req, _unused_call)
+    echo_req
+  end
+end
+
+# main starts an RpcServer that receives requests to EchoWithoutProtobuf at the sample
+# server port.
+def main
+  s = GRPC::RpcServer.new
+  s.add_http2_port('0.0.0.0:50051', :this_port_is_insecure)
+  s.handle(EchoServer)
+  s.run_till_terminated
+end
+
+main
diff --git a/examples/ruby/without_protobuf/echo_services_noprotobuf.rb b/examples/ruby/without_protobuf/echo_services_noprotobuf.rb
new file mode 100644
index 0000000..276ced6
--- /dev/null
+++ b/examples/ruby/without_protobuf/echo_services_noprotobuf.rb
@@ -0,0 +1,49 @@
+# Original file comments:
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#
+
+require 'grpc'
+
+module EchoWithoutProtobuf
+  # The 'echo without protobuf' service definition.
+  class Service
+
+    include GRPC::GenericService
+
+    self.marshal_class_method = :try_convert
+    self.unmarshal_class_method = :try_convert
+    self.service_name = 'EchoWithoutProtobuf'
+
+    # Request and response are plain strings
+    rpc :Echo, String, String
+  end
+
+  Stub = Service.rpc_stub_class
+end
diff --git a/grpc.gemspec b/grpc.gemspec
index 82c9d68..5cc7391 100755
--- a/grpc.gemspec
+++ b/grpc.gemspec
@@ -27,7 +27,7 @@
   s.require_paths = %w( src/ruby/bin src/ruby/lib src/ruby/pb )
   s.platform      = Gem::Platform::RUBY
 
-  s.add_dependency 'google-protobuf', '~> 3.1.0'
+  s.add_dependency 'google-protobuf', '~> 3.1'
   s.add_dependency 'googleauth',      '~> 0.5.1'
 
   s.add_development_dependency 'bundler',            '~> 1.9'
@@ -35,7 +35,7 @@
   s.add_development_dependency 'logging',            '~> 2.0'
   s.add_development_dependency 'simplecov',          '~> 0.9'
   s.add_development_dependency 'rake',               '~> 10.4'
-  s.add_development_dependency 'rake-compiler',      '~> 0.9'
+  s.add_development_dependency 'rake-compiler',      '~> 1.0'
   s.add_development_dependency 'rake-compiler-dock', '~> 0.5.1'
   s.add_development_dependency 'rspec',              '~> 3.2'
   s.add_development_dependency 'rubocop',            '~> 0.30.0'
diff --git a/include/grpc++/impl/codegen/server_context.h b/include/grpc++/impl/codegen/server_context.h
index 43bbff6..bf9a9b6 100644
--- a/include/grpc++/impl/codegen/server_context.h
+++ b/include/grpc++/impl/codegen/server_context.h
@@ -213,8 +213,7 @@
 
   void BeginCompletionOp(Call* call);
 
-  ServerContext(gpr_timespec deadline, grpc_metadata* metadata,
-                size_t metadata_count);
+  ServerContext(gpr_timespec deadline, grpc_metadata_array* arr);
 
   void set_call(grpc_call* call) { call_ = call; }
 
diff --git a/include/grpc/impl/codegen/port_platform.h b/include/grpc/impl/codegen/port_platform.h
index 4633fa1..e565cd3 100644
--- a/include/grpc/impl/codegen/port_platform.h
+++ b/include/grpc/impl/codegen/port_platform.h
@@ -297,6 +297,10 @@
 #endif
 
 #ifdef _MSC_VER
+#ifdef _PYTHON_MSVC
+// The Python 3.5 Windows runtime is missing InetNtop
+#define GPR_WIN_INET_NTOP
+#endif  // _PYTHON_MSVC
 #if _MSC_VER < 1700
 typedef __int8 int8_t;
 typedef __int16 int16_t;
diff --git a/setup.py b/setup.py
index ab21743..234252a 100644
--- a/setup.py
+++ b/setup.py
@@ -105,8 +105,11 @@
       EXTRA_ENV_COMPILE_ARGS += ' -D_ftime=_ftime32 -D_timeb=__timeb32 -D_ftime_s=_ftime32_s'
     else:
       EXTRA_ENV_COMPILE_ARGS += ' -D_ftime=_ftime64 -D_timeb=__timeb64'
+  elif 'win32' in sys.platform:
+    EXTRA_ENV_COMPILE_ARGS += ' -D_PYTHON_MSVC'
   elif "linux" in sys.platform or "darwin" in sys.platform:
     EXTRA_ENV_COMPILE_ARGS += ' -fvisibility=hidden -fno-wrapv'
+
 if EXTRA_ENV_LINK_ARGS is None:
   EXTRA_ENV_LINK_ARGS = ''
   if "linux" in sys.platform or "darwin" in sys.platform:
diff --git a/src/core/ext/client_channel/client_channel.c b/src/core/ext/client_channel/client_channel.c
index 6cbc333..21ba430 100644
--- a/src/core/ext/client_channel/client_channel.c
+++ b/src/core/ext/client_channel/client_channel.c
@@ -183,7 +183,7 @@
   grpc_pollset_set *interested_parties;
 
   /* the following properties are guarded by a mutex since API's require them
-     to be instantaniously available */
+     to be instantaneously available */
   gpr_mu info_mu;
   char *info_lb_policy_name;
   /** service config in JSON form */
@@ -200,9 +200,9 @@
   grpc_lb_policy *lb_policy;
 } lb_policy_connectivity_watcher;
 
-static void watch_lb_policy(grpc_exec_ctx *exec_ctx, channel_data *chand,
-                            grpc_lb_policy *lb_policy,
-                            grpc_connectivity_state current_state);
+static void watch_lb_policy_locked(grpc_exec_ctx *exec_ctx, channel_data *chand,
+                                   grpc_lb_policy *lb_policy,
+                                   grpc_connectivity_state current_state);
 
 static void set_channel_connectivity_state_locked(grpc_exec_ctx *exec_ctx,
                                                   channel_data *chand,
@@ -213,7 +213,7 @@
        state == GRPC_CHANNEL_SHUTDOWN) &&
       chand->lb_policy != NULL) {
     /* cancel picks with wait_for_ready=false */
-    grpc_lb_policy_cancel_picks(
+    grpc_lb_policy_cancel_picks_locked(
         exec_ctx, chand->lb_policy,
         /* mask= */ GRPC_INITIAL_METADATA_WAIT_FOR_READY,
         /* check= */ 0, GRPC_ERROR_REF(error));
@@ -237,7 +237,7 @@
     set_channel_connectivity_state_locked(exec_ctx, w->chand, publish_state,
                                           GRPC_ERROR_REF(error), "lb_changed");
     if (w->state != GRPC_CHANNEL_SHUTDOWN) {
-      watch_lb_policy(exec_ctx, w->chand, w->lb_policy, w->state);
+      watch_lb_policy_locked(exec_ctx, w->chand, w->lb_policy, w->state);
     }
   }
 
@@ -245,9 +245,9 @@
   gpr_free(w);
 }
 
-static void watch_lb_policy(grpc_exec_ctx *exec_ctx, channel_data *chand,
-                            grpc_lb_policy *lb_policy,
-                            grpc_connectivity_state current_state) {
+static void watch_lb_policy_locked(grpc_exec_ctx *exec_ctx, channel_data *chand,
+                                   grpc_lb_policy *lb_policy,
+                                   grpc_connectivity_state current_state) {
   lb_policy_connectivity_watcher *w = gpr_malloc(sizeof(*w));
   GRPC_CHANNEL_STACK_REF(chand->owning_stack, "watch_lb_policy");
 
@@ -256,8 +256,8 @@
                     grpc_combiner_scheduler(chand->combiner, false));
   w->state = current_state;
   w->lb_policy = lb_policy;
-  grpc_lb_policy_notify_on_state_change(exec_ctx, lb_policy, &w->state,
-                                        &w->on_changed);
+  grpc_lb_policy_notify_on_state_change_locked(exec_ctx, lb_policy, &w->state,
+                                               &w->on_changed);
 }
 
 static void on_resolver_result_changed_locked(grpc_exec_ctx *exec_ctx,
@@ -313,13 +313,14 @@
     grpc_lb_policy_args lb_policy_args;
     lb_policy_args.args = chand->resolver_result;
     lb_policy_args.client_channel_factory = chand->client_channel_factory;
+    lb_policy_args.combiner = chand->combiner;
     lb_policy =
         grpc_lb_policy_create(exec_ctx, lb_policy_name, &lb_policy_args);
     if (lb_policy != NULL) {
       GRPC_LB_POLICY_REF(lb_policy, "config_change");
       GRPC_ERROR_UNREF(state_error);
-      state =
-          grpc_lb_policy_check_connectivity(exec_ctx, lb_policy, &state_error);
+      state = grpc_lb_policy_check_connectivity_locked(exec_ctx, lb_policy,
+                                                       &state_error);
     }
     // Find service config.
     channel_arg =
@@ -383,7 +384,7 @@
     set_channel_connectivity_state_locked(
         exec_ctx, chand, state, GRPC_ERROR_REF(state_error), "new_lb+resolver");
     if (lb_policy != NULL) {
-      watch_lb_policy(exec_ctx, chand, lb_policy, state);
+      watch_lb_policy_locked(exec_ctx, chand, lb_policy, state);
     }
     GRPC_CHANNEL_STACK_REF(chand->owning_stack, "resolver");
     grpc_resolver_next_locked(exec_ctx, chand->resolver,
@@ -404,7 +405,7 @@
   }
 
   if (exit_idle) {
-    grpc_lb_policy_exit_idle(exec_ctx, lb_policy);
+    grpc_lb_policy_exit_idle_locked(exec_ctx, lb_policy);
     GRPC_LB_POLICY_UNREF(exec_ctx, lb_policy, "exit_idle");
   }
 
@@ -441,7 +442,7 @@
       grpc_closure_sched(exec_ctx, op->send_ping,
                          GRPC_ERROR_CREATE("Ping with no load balancing"));
     } else {
-      grpc_lb_policy_ping_one(exec_ctx, chand->lb_policy, op->send_ping);
+      grpc_lb_policy_ping_one_locked(exec_ctx, chand->lb_policy, op->send_ping);
       op->bind_pollset = NULL;
     }
     op->send_ping = NULL;
@@ -808,8 +809,9 @@
 
   if (initial_metadata == NULL) {
     if (chand->lb_policy != NULL) {
-      grpc_lb_policy_cancel_pick(exec_ctx, chand->lb_policy,
-                                 connected_subchannel, GRPC_ERROR_REF(error));
+      grpc_lb_policy_cancel_pick_locked(exec_ctx, chand->lb_policy,
+                                        connected_subchannel,
+                                        GRPC_ERROR_REF(error));
     }
     for (closure = chand->waiting_for_config_closures.head; closure != NULL;
          closure = closure->next_data.next) {
@@ -848,7 +850,7 @@
     const grpc_lb_policy_pick_args inputs = {
         initial_metadata, initial_metadata_flags, &calld->lb_token_mdelem,
         gpr_inf_future(GPR_CLOCK_MONOTONIC)};
-    const bool result = grpc_lb_policy_pick(
+    const bool result = grpc_lb_policy_pick_locked(
         exec_ctx, lb_policy, &inputs, connected_subchannel, NULL, on_ready);
     GRPC_LB_POLICY_UNREF(exec_ctx, lb_policy, "pick_subchannel");
     GPR_TIMER_END("pick_subchannel", 0);
@@ -1216,7 +1218,7 @@
                                   grpc_error *error_ignored) {
   channel_data *chand = arg;
   if (chand->lb_policy != NULL) {
-    grpc_lb_policy_exit_idle(exec_ctx, chand->lb_policy);
+    grpc_lb_policy_exit_idle_locked(exec_ctx, chand->lb_policy);
   } else {
     chand->exit_idle_when_lb_policy_arrives = true;
     if (!chand->started_resolving && chand->resolver != NULL) {
diff --git a/src/core/ext/client_channel/lb_policy.c b/src/core/ext/client_channel/lb_policy.c
index 90401b5..aba51ad 100644
--- a/src/core/ext/client_channel/lb_policy.c
+++ b/src/core/ext/client_channel/lb_policy.c
@@ -32,14 +32,17 @@
  */
 
 #include "src/core/ext/client_channel/lb_policy.h"
+#include "src/core/lib/iomgr/combiner.h"
 
 #define WEAK_REF_BITS 16
 
 void grpc_lb_policy_init(grpc_lb_policy *policy,
-                         const grpc_lb_policy_vtable *vtable) {
+                         const grpc_lb_policy_vtable *vtable,
+                         grpc_combiner *combiner) {
   policy->vtable = vtable;
   gpr_atm_no_barrier_store(&policy->ref_pair, 1 << WEAK_REF_BITS);
   policy->interested_parties = grpc_pollset_set_create();
+  policy->combiner = GRPC_COMBINER_REF(combiner, "lb_policy");
 }
 
 #ifdef GRPC_LB_POLICY_REFCOUNT_DEBUG
@@ -71,6 +74,13 @@
   ref_mutate(policy, 1 << WEAK_REF_BITS, 0 REF_MUTATE_PASS_ARGS("STRONG_REF"));
 }
 
+static void shutdown_locked(grpc_exec_ctx *exec_ctx, void *arg,
+                            grpc_error *error) {
+  grpc_lb_policy *policy = arg;
+  policy->vtable->shutdown_locked(exec_ctx, policy);
+  GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, policy, "strong-unref");
+}
+
 void grpc_lb_policy_unref(grpc_exec_ctx *exec_ctx,
                           grpc_lb_policy *policy REF_FUNC_EXTRA_ARGS) {
   gpr_atm old_val =
@@ -79,10 +89,15 @@
   gpr_atm mask = ~(gpr_atm)((1 << WEAK_REF_BITS) - 1);
   gpr_atm check = 1 << WEAK_REF_BITS;
   if ((old_val & mask) == check) {
-    policy->vtable->shutdown(exec_ctx, policy);
+    grpc_closure_sched(
+        exec_ctx,
+        grpc_closure_create(shutdown_locked, policy,
+                            grpc_combiner_scheduler(policy->combiner, false)),
+        GRPC_ERROR_NONE);
+  } else {
+    grpc_lb_policy_weak_unref(exec_ctx,
+                              policy REF_FUNC_PASS_ARGS("strong-unref"));
   }
-  grpc_lb_policy_weak_unref(exec_ctx,
-                            policy REF_FUNC_PASS_ARGS("strong-unref"));
 }
 
 void grpc_lb_policy_weak_ref(grpc_lb_policy *policy REF_FUNC_EXTRA_ARGS) {
@@ -95,52 +110,58 @@
       ref_mutate(policy, -(gpr_atm)1, 1 REF_MUTATE_PASS_ARGS("WEAK_UNREF"));
   if (old_val == 1) {
     grpc_pollset_set_destroy(exec_ctx, policy->interested_parties);
+    grpc_combiner *combiner = policy->combiner;
     policy->vtable->destroy(exec_ctx, policy);
+    GRPC_COMBINER_UNREF(exec_ctx, combiner, "lb_policy");
   }
 }
 
-int grpc_lb_policy_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
-                        const grpc_lb_policy_pick_args *pick_args,
-                        grpc_connected_subchannel **target, void **user_data,
-                        grpc_closure *on_complete) {
-  return policy->vtable->pick(exec_ctx, policy, pick_args, target, user_data,
-                              on_complete);
+int grpc_lb_policy_pick_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
+                               const grpc_lb_policy_pick_args *pick_args,
+                               grpc_connected_subchannel **target,
+                               void **user_data, grpc_closure *on_complete) {
+  return policy->vtable->pick_locked(exec_ctx, policy, pick_args, target,
+                                     user_data, on_complete);
 }
 
-void grpc_lb_policy_cancel_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
-                                grpc_connected_subchannel **target,
-                                grpc_error *error) {
-  policy->vtable->cancel_pick(exec_ctx, policy, target, error);
+void grpc_lb_policy_cancel_pick_locked(grpc_exec_ctx *exec_ctx,
+                                       grpc_lb_policy *policy,
+                                       grpc_connected_subchannel **target,
+                                       grpc_error *error) {
+  policy->vtable->cancel_pick_locked(exec_ctx, policy, target, error);
 }
 
-void grpc_lb_policy_cancel_picks(grpc_exec_ctx *exec_ctx,
-                                 grpc_lb_policy *policy,
-                                 uint32_t initial_metadata_flags_mask,
-                                 uint32_t initial_metadata_flags_eq,
-                                 grpc_error *error) {
-  policy->vtable->cancel_picks(exec_ctx, policy, initial_metadata_flags_mask,
-                               initial_metadata_flags_eq, error);
+void grpc_lb_policy_cancel_picks_locked(grpc_exec_ctx *exec_ctx,
+                                        grpc_lb_policy *policy,
+                                        uint32_t initial_metadata_flags_mask,
+                                        uint32_t initial_metadata_flags_eq,
+                                        grpc_error *error) {
+  policy->vtable->cancel_picks_locked(exec_ctx, policy,
+                                      initial_metadata_flags_mask,
+                                      initial_metadata_flags_eq, error);
 }
 
-void grpc_lb_policy_exit_idle(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy) {
-  policy->vtable->exit_idle(exec_ctx, policy);
+void grpc_lb_policy_exit_idle_locked(grpc_exec_ctx *exec_ctx,
+                                     grpc_lb_policy *policy) {
+  policy->vtable->exit_idle_locked(exec_ctx, policy);
 }
 
-void grpc_lb_policy_ping_one(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
-                             grpc_closure *closure) {
-  policy->vtable->ping_one(exec_ctx, policy, closure);
+void grpc_lb_policy_ping_one_locked(grpc_exec_ctx *exec_ctx,
+                                    grpc_lb_policy *policy,
+                                    grpc_closure *closure) {
+  policy->vtable->ping_one_locked(exec_ctx, policy, closure);
 }
 
-void grpc_lb_policy_notify_on_state_change(grpc_exec_ctx *exec_ctx,
-                                           grpc_lb_policy *policy,
-                                           grpc_connectivity_state *state,
-                                           grpc_closure *closure) {
-  policy->vtable->notify_on_state_change(exec_ctx, policy, state, closure);
+void grpc_lb_policy_notify_on_state_change_locked(
+    grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
+    grpc_connectivity_state *state, grpc_closure *closure) {
+  policy->vtable->notify_on_state_change_locked(exec_ctx, policy, state,
+                                                closure);
 }
 
-grpc_connectivity_state grpc_lb_policy_check_connectivity(
+grpc_connectivity_state grpc_lb_policy_check_connectivity_locked(
     grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
     grpc_error **connectivity_error) {
-  return policy->vtable->check_connectivity(exec_ctx, policy,
-                                            connectivity_error);
+  return policy->vtable->check_connectivity_locked(exec_ctx, policy,
+                                                   connectivity_error);
 }
diff --git a/src/core/ext/client_channel/lb_policy.h b/src/core/ext/client_channel/lb_policy.h
index 120c641..3405709 100644
--- a/src/core/ext/client_channel/lb_policy.h
+++ b/src/core/ext/client_channel/lb_policy.h
@@ -51,6 +51,8 @@
   gpr_atm ref_pair;
   /* owned pointer to interested parties in load balancing decisions */
   grpc_pollset_set *interested_parties;
+  /* combiner under which lb_policy actions take place */
+  grpc_combiner *combiner;
 };
 
 /** Extra arguments for an LB pick */
@@ -69,42 +71,44 @@
 
 struct grpc_lb_policy_vtable {
   void (*destroy)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy);
-  void (*shutdown)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy);
+  void (*shutdown_locked)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy);
 
   /** \see grpc_lb_policy_pick */
-  int (*pick)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
-              const grpc_lb_policy_pick_args *pick_args,
-              grpc_connected_subchannel **target, void **user_data,
-              grpc_closure *on_complete);
+  int (*pick_locked)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
+                     const grpc_lb_policy_pick_args *pick_args,
+                     grpc_connected_subchannel **target, void **user_data,
+                     grpc_closure *on_complete);
 
   /** \see grpc_lb_policy_cancel_pick */
-  void (*cancel_pick)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
-                      grpc_connected_subchannel **target, grpc_error *error);
+  void (*cancel_pick_locked)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
+                             grpc_connected_subchannel **target,
+                             grpc_error *error);
 
   /** \see grpc_lb_policy_cancel_picks */
-  void (*cancel_picks)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
-                       uint32_t initial_metadata_flags_mask,
-                       uint32_t initial_metadata_flags_eq, grpc_error *error);
+  void (*cancel_picks_locked)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
+                              uint32_t initial_metadata_flags_mask,
+                              uint32_t initial_metadata_flags_eq,
+                              grpc_error *error);
 
   /** \see grpc_lb_policy_ping_one */
-  void (*ping_one)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
-                   grpc_closure *closure);
+  void (*ping_one_locked)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
+                          grpc_closure *closure);
 
   /** Try to enter a READY connectivity state */
-  void (*exit_idle)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy);
+  void (*exit_idle_locked)(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy);
 
   /** check the current connectivity of the lb_policy */
-  grpc_connectivity_state (*check_connectivity)(
+  grpc_connectivity_state (*check_connectivity_locked)(
       grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
       grpc_error **connectivity_error);
 
   /** call notify when the connectivity state of a channel changes from *state.
       Updates *state with the new state of the policy. Calling with a NULL \a
       state cancels the subscription.  */
-  void (*notify_on_state_change)(grpc_exec_ctx *exec_ctx,
-                                 grpc_lb_policy *policy,
-                                 grpc_connectivity_state *state,
-                                 grpc_closure *closure);
+  void (*notify_on_state_change_locked)(grpc_exec_ctx *exec_ctx,
+                                        grpc_lb_policy *policy,
+                                        grpc_connectivity_state *state,
+                                        grpc_closure *closure);
 };
 
 /*#define GRPC_LB_POLICY_REFCOUNT_DEBUG*/
@@ -144,7 +148,8 @@
 
 /** called by concrete implementations to initialize the base struct */
 void grpc_lb_policy_init(grpc_lb_policy *policy,
-                         const grpc_lb_policy_vtable *vtable);
+                         const grpc_lb_policy_vtable *vtable,
+                         grpc_combiner *combiner);
 
 /** Finds an appropriate subchannel for a call, based on \a pick_args.
 
@@ -159,43 +164,45 @@
 
     Any IO should be done under the \a interested_parties \a grpc_pollset_set
     in the \a grpc_lb_policy struct. */
-int grpc_lb_policy_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
-                        const grpc_lb_policy_pick_args *pick_args,
-                        grpc_connected_subchannel **target, void **user_data,
-                        grpc_closure *on_complete);
+int grpc_lb_policy_pick_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
+                               const grpc_lb_policy_pick_args *pick_args,
+                               grpc_connected_subchannel **target,
+                               void **user_data, grpc_closure *on_complete);
 
 /** Perform a connected subchannel ping (see \a grpc_connected_subchannel_ping)
     against one of the connected subchannels managed by \a policy. */
-void grpc_lb_policy_ping_one(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
-                             grpc_closure *closure);
+void grpc_lb_policy_ping_one_locked(grpc_exec_ctx *exec_ctx,
+                                    grpc_lb_policy *policy,
+                                    grpc_closure *closure);
 
 /** Cancel picks for \a target.
     The \a on_complete callback of the pending picks will be invoked with \a
     *target set to NULL. */
-void grpc_lb_policy_cancel_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
-                                grpc_connected_subchannel **target,
-                                grpc_error *error);
+void grpc_lb_policy_cancel_pick_locked(grpc_exec_ctx *exec_ctx,
+                                       grpc_lb_policy *policy,
+                                       grpc_connected_subchannel **target,
+                                       grpc_error *error);
 
 /** Cancel all pending picks for which their \a initial_metadata_flags (as given
     in the call to \a grpc_lb_policy_pick) matches \a initial_metadata_flags_eq
     when AND'd with \a initial_metadata_flags_mask */
-void grpc_lb_policy_cancel_picks(grpc_exec_ctx *exec_ctx,
-                                 grpc_lb_policy *policy,
-                                 uint32_t initial_metadata_flags_mask,
-                                 uint32_t initial_metadata_flags_eq,
-                                 grpc_error *error);
+void grpc_lb_policy_cancel_picks_locked(grpc_exec_ctx *exec_ctx,
+                                        grpc_lb_policy *policy,
+                                        uint32_t initial_metadata_flags_mask,
+                                        uint32_t initial_metadata_flags_eq,
+                                        grpc_error *error);
 
 /** Try to enter a READY connectivity state */
-void grpc_lb_policy_exit_idle(grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy);
+void grpc_lb_policy_exit_idle_locked(grpc_exec_ctx *exec_ctx,
+                                     grpc_lb_policy *policy);
 
 /* Call notify when the connectivity state of a channel changes from \a *state.
  * Updates \a *state with the new state of the policy */
-void grpc_lb_policy_notify_on_state_change(grpc_exec_ctx *exec_ctx,
-                                           grpc_lb_policy *policy,
-                                           grpc_connectivity_state *state,
-                                           grpc_closure *closure);
+void grpc_lb_policy_notify_on_state_change_locked(
+    grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
+    grpc_connectivity_state *state, grpc_closure *closure);
 
-grpc_connectivity_state grpc_lb_policy_check_connectivity(
+grpc_connectivity_state grpc_lb_policy_check_connectivity_locked(
     grpc_exec_ctx *exec_ctx, grpc_lb_policy *policy,
     grpc_error **connectivity_error);
 
diff --git a/src/core/ext/client_channel/lb_policy_factory.h b/src/core/ext/client_channel/lb_policy_factory.h
index 9b8b03f..27c12c0 100644
--- a/src/core/ext/client_channel/lb_policy_factory.h
+++ b/src/core/ext/client_channel/lb_policy_factory.h
@@ -107,6 +107,7 @@
 typedef struct grpc_lb_policy_args {
   grpc_client_channel_factory *client_channel_factory;
   grpc_channel_args *args;
+  grpc_combiner *combiner;
 } grpc_lb_policy_args;
 
 struct grpc_lb_policy_factory_vtable {
diff --git a/src/core/ext/client_channel/subchannel.c b/src/core/ext/client_channel/subchannel.c
index 09c68a9..f2da148 100644
--- a/src/core/ext/client_channel/subchannel.c
+++ b/src/core/ext/client_channel/subchannel.c
@@ -438,7 +438,7 @@
   gpr_mu_unlock(&w->subchannel->mu);
   GRPC_SUBCHANNEL_WEAK_UNREF(exec_ctx, w->subchannel, "external_state_watcher");
   gpr_free(w);
-  follow_up->cb(exec_ctx, follow_up->cb_arg, error);
+  grpc_closure_run(exec_ctx, follow_up, GRPC_ERROR_REF(error));
 }
 
 static void on_alarm(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) {
diff --git a/src/core/ext/lb_policy/grpclb/grpclb.c b/src/core/ext/lb_policy/grpclb/grpclb.c
index 8a2af48..b5210cb 100644
--- a/src/core/ext/lb_policy/grpclb/grpclb.c
+++ b/src/core/ext/lb_policy/grpclb/grpclb.c
@@ -115,6 +115,7 @@
 #include "src/core/ext/lb_policy/grpclb/grpclb_channel.h"
 #include "src/core/ext/lb_policy/grpclb/load_balancer_api.h"
 #include "src/core/lib/channel/channel_args.h"
+#include "src/core/lib/iomgr/combiner.h"
 #include "src/core/lib/iomgr/sockaddr.h"
 #include "src/core/lib/iomgr/sockaddr_utils.h"
 #include "src/core/lib/iomgr/timer.h"
@@ -285,9 +286,6 @@
   /** base policy: must be first */
   grpc_lb_policy base;
 
-  /** mutex protecting remaining members */
-  gpr_mu mu;
-
   /** who the client is trying to communicate with */
   const char *server_name;
   grpc_client_channel_factory *cc_factory;
@@ -557,9 +555,9 @@
     const grpc_lb_policy_pick_args *pick_args,
     grpc_connected_subchannel **target, wrapped_rr_closure_arg *wc_arg) {
   GPR_ASSERT(rr_policy != NULL);
-  const bool pick_done =
-      grpc_lb_policy_pick(exec_ctx, rr_policy, pick_args, target,
-                          (void **)&wc_arg->lb_token, &wc_arg->wrapper_closure);
+  const bool pick_done = grpc_lb_policy_pick_locked(
+      exec_ctx, rr_policy, pick_args, target, (void **)&wc_arg->lb_token,
+      &wc_arg->wrapper_closure);
   if (pick_done) {
     /* synchronous grpc_lb_policy_pick call. Unref the RR policy. */
     if (grpc_lb_glb_trace) {
@@ -590,6 +588,7 @@
   grpc_lb_policy_args args;
   memset(&args, 0, sizeof(args));
   args.client_channel_factory = glb_policy->cc_factory;
+  args.combiner = glb_policy->base.combiner;
   grpc_lb_addresses *addresses =
       process_serverlist_locked(exec_ctx, serverlist);
 
@@ -608,8 +607,8 @@
   return rr;
 }
 
-static void glb_rr_connectivity_changed(grpc_exec_ctx *exec_ctx, void *arg,
-                                        grpc_error *error);
+static void glb_rr_connectivity_changed_locked(grpc_exec_ctx *exec_ctx,
+                                               void *arg, grpc_error *error);
 /* glb_policy->rr_policy may be NULL (initial handover) */
 static void rr_handover_locked(grpc_exec_ctx *exec_ctx,
                                glb_lb_policy *glb_policy) {
@@ -633,8 +632,8 @@
 
   grpc_error *new_rr_state_error = NULL;
   const grpc_connectivity_state new_rr_state =
-      grpc_lb_policy_check_connectivity(exec_ctx, new_rr_policy,
-                                        &new_rr_state_error);
+      grpc_lb_policy_check_connectivity_locked(exec_ctx, new_rr_policy,
+                                               &new_rr_state_error);
   /* Connectivity state is a function of the new RR policy just created */
   const bool replace_old_rr = update_lb_connectivity_status_locked(
       exec_ctx, glb_policy, new_rr_state, new_rr_state_error);
@@ -677,17 +676,18 @@
   rr_connectivity_data *rr_connectivity =
       gpr_malloc(sizeof(rr_connectivity_data));
   memset(rr_connectivity, 0, sizeof(rr_connectivity_data));
-  grpc_closure_init(&rr_connectivity->on_change, glb_rr_connectivity_changed,
-                    rr_connectivity, grpc_schedule_on_exec_ctx);
+  grpc_closure_init(&rr_connectivity->on_change,
+                    glb_rr_connectivity_changed_locked, rr_connectivity,
+                    grpc_combiner_scheduler(glb_policy->base.combiner, false));
   rr_connectivity->glb_policy = glb_policy;
   rr_connectivity->state = new_rr_state;
 
   /* Subscribe to changes to the connectivity of the new RR */
   GRPC_LB_POLICY_WEAK_REF(&glb_policy->base, "rr_connectivity_cb");
-  grpc_lb_policy_notify_on_state_change(exec_ctx, glb_policy->rr_policy,
-                                        &rr_connectivity->state,
-                                        &rr_connectivity->on_change);
-  grpc_lb_policy_exit_idle(exec_ctx, glb_policy->rr_policy);
+  grpc_lb_policy_notify_on_state_change_locked(exec_ctx, glb_policy->rr_policy,
+                                               &rr_connectivity->state,
+                                               &rr_connectivity->on_change);
+  grpc_lb_policy_exit_idle_locked(exec_ctx, glb_policy->rr_policy);
 
   /* Update picks and pings in wait */
   pending_pick *pp;
@@ -713,17 +713,16 @@
       gpr_log(GPR_INFO, "Pending ping about to PING from 0x%" PRIxPTR "",
               (intptr_t)glb_policy->rr_policy);
     }
-    grpc_lb_policy_ping_one(exec_ctx, glb_policy->rr_policy,
-                            &pping->wrapped_notify_arg.wrapper_closure);
+    grpc_lb_policy_ping_one_locked(exec_ctx, glb_policy->rr_policy,
+                                   &pping->wrapped_notify_arg.wrapper_closure);
   }
 }
 
-static void glb_rr_connectivity_changed(grpc_exec_ctx *exec_ctx, void *arg,
-                                        grpc_error *error) {
+static void glb_rr_connectivity_changed_locked(grpc_exec_ctx *exec_ctx,
+                                               void *arg, grpc_error *error) {
   rr_connectivity_data *rr_connectivity = arg;
   glb_lb_policy *glb_policy = rr_connectivity->glb_policy;
 
-  gpr_mu_lock(&glb_policy->mu);
   const bool shutting_down = glb_policy->shutting_down;
   bool unref_needed = false;
   GRPC_ERROR_REF(error);
@@ -740,11 +739,10 @@
     update_lb_connectivity_status_locked(exec_ctx, glb_policy,
                                          rr_connectivity->state, error);
     /* Resubscribe. Reuse the "rr_connectivity_cb" weak ref. */
-    grpc_lb_policy_notify_on_state_change(exec_ctx, glb_policy->rr_policy,
-                                          &rr_connectivity->state,
-                                          &rr_connectivity->on_change);
+    grpc_lb_policy_notify_on_state_change_locked(
+        exec_ctx, glb_policy->rr_policy, &rr_connectivity->state,
+        &rr_connectivity->on_change);
   }
-  gpr_mu_unlock(&glb_policy->mu);
   if (unref_needed) {
     GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &glb_policy->base,
                               "rr_connectivity_cb");
@@ -899,8 +897,7 @@
     gpr_free(glb_policy);
     return NULL;
   }
-  grpc_lb_policy_init(&glb_policy->base, &glb_lb_policy_vtable);
-  gpr_mu_init(&glb_policy->mu);
+  grpc_lb_policy_init(&glb_policy->base, &glb_lb_policy_vtable, args->combiner);
   grpc_connectivity_state_init(&glb_policy->state_tracker, GRPC_CHANNEL_IDLE,
                                "grpclb");
   return &glb_policy->base;
@@ -918,13 +915,11 @@
   if (glb_policy->serverlist != NULL) {
     grpc_grpclb_destroy_serverlist(glb_policy->serverlist);
   }
-  gpr_mu_destroy(&glb_policy->mu);
   gpr_free(glb_policy);
 }
 
-static void glb_shutdown(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
+static void glb_shutdown_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
   glb_lb_policy *glb_policy = (glb_lb_policy *)pol;
-  gpr_mu_lock(&glb_policy->mu);
   glb_policy->shutting_down = true;
 
   pending_pick *pp = glb_policy->pending_picks;
@@ -941,7 +936,6 @@
    * while holding glb_policy->mu: lb_on_server_status_received, invoked due to
    * the cancel, needs to acquire that same lock */
   grpc_call *lb_call = glb_policy->lb_call;
-  gpr_mu_unlock(&glb_policy->mu);
 
   /* glb_policy->lb_call and this local lb_call must be consistent at this point
    * because glb_policy->lb_call is only assigned in lb_call_init_locked as part
@@ -967,11 +961,10 @@
   }
 }
 
-static void glb_cancel_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
-                            grpc_connected_subchannel **target,
-                            grpc_error *error) {
+static void glb_cancel_pick_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
+                                   grpc_connected_subchannel **target,
+                                   grpc_error *error) {
   glb_lb_policy *glb_policy = (glb_lb_policy *)pol;
-  gpr_mu_lock(&glb_policy->mu);
   pending_pick *pp = glb_policy->pending_picks;
   glb_policy->pending_picks = NULL;
   while (pp != NULL) {
@@ -987,16 +980,15 @@
     }
     pp = next;
   }
-  gpr_mu_unlock(&glb_policy->mu);
   GRPC_ERROR_UNREF(error);
 }
 
-static void glb_cancel_picks(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
-                             uint32_t initial_metadata_flags_mask,
-                             uint32_t initial_metadata_flags_eq,
-                             grpc_error *error) {
+static void glb_cancel_picks_locked(grpc_exec_ctx *exec_ctx,
+                                    grpc_lb_policy *pol,
+                                    uint32_t initial_metadata_flags_mask,
+                                    uint32_t initial_metadata_flags_eq,
+                                    grpc_error *error) {
   glb_lb_policy *glb_policy = (glb_lb_policy *)pol;
-  gpr_mu_lock(&glb_policy->mu);
   pending_pick *pp = glb_policy->pending_picks;
   glb_policy->pending_picks = NULL;
   while (pp != NULL) {
@@ -1012,7 +1004,6 @@
     }
     pp = next;
   }
-  gpr_mu_unlock(&glb_policy->mu);
   GRPC_ERROR_UNREF(error);
 }
 
@@ -1025,19 +1016,17 @@
   query_for_backends_locked(exec_ctx, glb_policy);
 }
 
-static void glb_exit_idle(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
+static void glb_exit_idle_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
   glb_lb_policy *glb_policy = (glb_lb_policy *)pol;
-  gpr_mu_lock(&glb_policy->mu);
   if (!glb_policy->started_picking) {
     start_picking_locked(exec_ctx, glb_policy);
   }
-  gpr_mu_unlock(&glb_policy->mu);
 }
 
-static int glb_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
-                    const grpc_lb_policy_pick_args *pick_args,
-                    grpc_connected_subchannel **target, void **user_data,
-                    grpc_closure *on_complete) {
+static int glb_pick_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
+                           const grpc_lb_policy_pick_args *pick_args,
+                           grpc_connected_subchannel **target, void **user_data,
+                           grpc_closure *on_complete) {
   if (pick_args->lb_token_mdelem_storage == NULL) {
     *target = NULL;
     grpc_closure_sched(
@@ -1048,7 +1037,6 @@
   }
 
   glb_lb_policy *glb_policy = (glb_lb_policy *)pol;
-  gpr_mu_lock(&glb_policy->mu);
   glb_policy->deadline = pick_args->deadline;
   bool pick_done;
 
@@ -1087,53 +1075,43 @@
     }
     pick_done = false;
   }
-  gpr_mu_unlock(&glb_policy->mu);
   return pick_done;
 }
 
-static grpc_connectivity_state glb_check_connectivity(
+static grpc_connectivity_state glb_check_connectivity_locked(
     grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
     grpc_error **connectivity_error) {
   glb_lb_policy *glb_policy = (glb_lb_policy *)pol;
-  grpc_connectivity_state st;
-  gpr_mu_lock(&glb_policy->mu);
-  st = grpc_connectivity_state_get(&glb_policy->state_tracker,
-                                   connectivity_error);
-  gpr_mu_unlock(&glb_policy->mu);
-  return st;
+  return grpc_connectivity_state_get(&glb_policy->state_tracker,
+                                     connectivity_error);
 }
 
-static void glb_ping_one(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
-                         grpc_closure *closure) {
+static void glb_ping_one_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
+                                grpc_closure *closure) {
   glb_lb_policy *glb_policy = (glb_lb_policy *)pol;
-  gpr_mu_lock(&glb_policy->mu);
   if (glb_policy->rr_policy) {
-    grpc_lb_policy_ping_one(exec_ctx, glb_policy->rr_policy, closure);
+    grpc_lb_policy_ping_one_locked(exec_ctx, glb_policy->rr_policy, closure);
   } else {
     add_pending_ping(&glb_policy->pending_pings, closure);
     if (!glb_policy->started_picking) {
       start_picking_locked(exec_ctx, glb_policy);
     }
   }
-  gpr_mu_unlock(&glb_policy->mu);
 }
 
-static void glb_notify_on_state_change(grpc_exec_ctx *exec_ctx,
-                                       grpc_lb_policy *pol,
-                                       grpc_connectivity_state *current,
-                                       grpc_closure *notify) {
+static void glb_notify_on_state_change_locked(grpc_exec_ctx *exec_ctx,
+                                              grpc_lb_policy *pol,
+                                              grpc_connectivity_state *current,
+                                              grpc_closure *notify) {
   glb_lb_policy *glb_policy = (glb_lb_policy *)pol;
-  gpr_mu_lock(&glb_policy->mu);
   grpc_connectivity_state_notify_on_state_change(
       exec_ctx, &glb_policy->state_tracker, current, notify);
-
-  gpr_mu_unlock(&glb_policy->mu);
 }
 
-static void lb_on_server_status_received(grpc_exec_ctx *exec_ctx, void *arg,
-                                         grpc_error *error);
-static void lb_on_response_received(grpc_exec_ctx *exec_ctx, void *arg,
-                                    grpc_error *error);
+static void lb_on_server_status_received_locked(grpc_exec_ctx *exec_ctx,
+                                                void *arg, grpc_error *error);
+static void lb_on_response_received_locked(grpc_exec_ctx *exec_ctx, void *arg,
+                                           grpc_error *error);
 static void lb_call_init_locked(grpc_exec_ctx *exec_ctx,
                                 glb_lb_policy *glb_policy) {
   GPR_ASSERT(glb_policy->server_name != NULL);
@@ -1162,11 +1140,11 @@
   grpc_grpclb_request_destroy(request);
 
   grpc_closure_init(&glb_policy->lb_on_server_status_received,
-                    lb_on_server_status_received, glb_policy,
-                    grpc_schedule_on_exec_ctx);
+                    lb_on_server_status_received_locked, glb_policy,
+                    grpc_combiner_scheduler(glb_policy->base.combiner, false));
   grpc_closure_init(&glb_policy->lb_on_response_received,
-                    lb_on_response_received, glb_policy,
-                    grpc_schedule_on_exec_ctx);
+                    lb_on_response_received_locked, glb_policy,
+                    grpc_combiner_scheduler(glb_policy->base.combiner, false));
 
   gpr_backoff_init(&glb_policy->lb_call_backoff_state,
                    GRPC_GRPCLB_INITIAL_CONNECT_BACKOFF_SECONDS,
@@ -1261,14 +1239,13 @@
   GPR_ASSERT(GRPC_CALL_OK == call_error);
 }
 
-static void lb_on_response_received(grpc_exec_ctx *exec_ctx, void *arg,
-                                    grpc_error *error) {
+static void lb_on_response_received_locked(grpc_exec_ctx *exec_ctx, void *arg,
+                                           grpc_error *error) {
   glb_lb_policy *glb_policy = arg;
 
   grpc_op ops[2];
   memset(ops, 0, sizeof(ops));
   grpc_op *op = ops;
-  gpr_mu_lock(&glb_policy->mu);
   if (glb_policy->lb_response_payload != NULL) {
     gpr_backoff_reset(&glb_policy->lb_call_backoff_state);
     /* Received data from the LB server. Look inside
@@ -1342,20 +1319,17 @@
           &glb_policy->lb_on_response_received); /* loop */
       GPR_ASSERT(GRPC_CALL_OK == call_error);
     }
-    gpr_mu_unlock(&glb_policy->mu);
   } else { /* empty payload: call cancelled. */
            /* dispose of the "lb_on_response_received" weak ref taken in
             * query_for_backends_locked() and reused in every reception loop */
-    gpr_mu_unlock(&glb_policy->mu);
     GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &glb_policy->base,
                               "lb_on_response_received_empty_payload");
   }
 }
 
-static void lb_call_on_retry_timer(grpc_exec_ctx *exec_ctx, void *arg,
-                                   grpc_error *error) {
+static void lb_call_on_retry_timer_locked(grpc_exec_ctx *exec_ctx, void *arg,
+                                          grpc_error *error) {
   glb_lb_policy *glb_policy = arg;
-  gpr_mu_lock(&glb_policy->mu);
 
   if (!glb_policy->shutting_down) {
     if (grpc_lb_glb_trace) {
@@ -1365,15 +1339,13 @@
     GPR_ASSERT(glb_policy->lb_call == NULL);
     query_for_backends_locked(exec_ctx, glb_policy);
   }
-  gpr_mu_unlock(&glb_policy->mu);
   GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &glb_policy->base,
                             "grpclb_on_retry_timer");
 }
 
-static void lb_on_server_status_received(grpc_exec_ctx *exec_ctx, void *arg,
-                                         grpc_error *error) {
+static void lb_on_server_status_received_locked(grpc_exec_ctx *exec_ctx,
+                                                void *arg, grpc_error *error) {
   glb_lb_policy *glb_policy = arg;
-  gpr_mu_lock(&glb_policy->mu);
 
   GPR_ASSERT(glb_policy->lb_call != NULL);
 
@@ -1408,21 +1380,27 @@
       }
     }
     GRPC_LB_POLICY_WEAK_REF(&glb_policy->base, "grpclb_retry_timer");
-    grpc_closure_init(&glb_policy->lb_on_call_retry, lb_call_on_retry_timer,
-                      glb_policy, grpc_schedule_on_exec_ctx);
+    grpc_closure_init(
+        &glb_policy->lb_on_call_retry, lb_call_on_retry_timer_locked,
+        glb_policy, grpc_combiner_scheduler(glb_policy->base.combiner, false));
     grpc_timer_init(exec_ctx, &glb_policy->lb_call_retry_timer, next_try,
                     &glb_policy->lb_on_call_retry, now);
   }
-  gpr_mu_unlock(&glb_policy->mu);
   GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &glb_policy->base,
                             "lb_on_server_status_received");
 }
 
 /* Code wiring the policy with the rest of the core */
 static const grpc_lb_policy_vtable glb_lb_policy_vtable = {
-    glb_destroy,     glb_shutdown,           glb_pick,
-    glb_cancel_pick, glb_cancel_picks,       glb_ping_one,
-    glb_exit_idle,   glb_check_connectivity, glb_notify_on_state_change};
+    glb_destroy,
+    glb_shutdown_locked,
+    glb_pick_locked,
+    glb_cancel_pick_locked,
+    glb_cancel_picks_locked,
+    glb_ping_one_locked,
+    glb_exit_idle_locked,
+    glb_check_connectivity_locked,
+    glb_notify_on_state_change_locked};
 
 static void glb_factory_ref(grpc_lb_policy_factory *factory) {}
 
diff --git a/src/core/ext/lb_policy/pick_first/pick_first.c b/src/core/ext/lb_policy/pick_first/pick_first.c
index 1b96518..501cb6d 100644
--- a/src/core/ext/lb_policy/pick_first/pick_first.c
+++ b/src/core/ext/lb_policy/pick_first/pick_first.c
@@ -38,6 +38,7 @@
 #include "src/core/ext/client_channel/lb_policy_registry.h"
 #include "src/core/ext/client_channel/subchannel.h"
 #include "src/core/lib/channel/channel_args.h"
+#include "src/core/lib/iomgr/combiner.h"
 #include "src/core/lib/iomgr/sockaddr_utils.h"
 #include "src/core/lib/transport/connectivity_state.h"
 
@@ -57,11 +58,11 @@
 
   grpc_closure connectivity_changed;
 
-  /** the selected channel (a grpc_connected_subchannel) */
-  gpr_atm selected;
+  /** remaining members are protected by the combiner */
 
-  /** mutex protecting remaining members */
-  gpr_mu mu;
+  /** the selected channel */
+  grpc_connected_subchannel *selected;
+
   /** have we started picking? */
   int started_picking;
   /** are we shut down? */
@@ -77,32 +78,24 @@
   grpc_connectivity_state_tracker state_tracker;
 } pick_first_lb_policy;
 
-#define GET_SELECTED(p) \
-  ((grpc_connected_subchannel *)gpr_atm_acq_load(&(p)->selected))
-
 static void pf_destroy(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
   pick_first_lb_policy *p = (pick_first_lb_policy *)pol;
-  grpc_connected_subchannel *selected = GET_SELECTED(p);
   size_t i;
   GPR_ASSERT(p->pending_picks == NULL);
   for (i = 0; i < p->num_subchannels; i++) {
     GRPC_SUBCHANNEL_UNREF(exec_ctx, p->subchannels[i], "pick_first");
   }
-  if (selected != NULL) {
-    GRPC_CONNECTED_SUBCHANNEL_UNREF(exec_ctx, selected, "picked_first");
+  if (p->selected != NULL) {
+    GRPC_CONNECTED_SUBCHANNEL_UNREF(exec_ctx, p->selected, "picked_first");
   }
   grpc_connectivity_state_destroy(exec_ctx, &p->state_tracker);
   gpr_free(p->subchannels);
-  gpr_mu_destroy(&p->mu);
   gpr_free(p);
 }
 
-static void pf_shutdown(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
+static void pf_shutdown_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
   pick_first_lb_policy *p = (pick_first_lb_policy *)pol;
   pending_pick *pp;
-  grpc_connected_subchannel *selected;
-  gpr_mu_lock(&p->mu);
-  selected = GET_SELECTED(p);
   p->shutdown = 1;
   pp = p->pending_picks;
   p->pending_picks = NULL;
@@ -110,15 +103,14 @@
       exec_ctx, &p->state_tracker, GRPC_CHANNEL_SHUTDOWN,
       GRPC_ERROR_CREATE("Channel shutdown"), "shutdown");
   /* cancel subscription */
-  if (selected != NULL) {
+  if (p->selected != NULL) {
     grpc_connected_subchannel_notify_on_state_change(
-        exec_ctx, selected, NULL, NULL, &p->connectivity_changed);
+        exec_ctx, p->selected, NULL, NULL, &p->connectivity_changed);
   } else if (p->num_subchannels > 0) {
     grpc_subchannel_notify_on_state_change(
         exec_ctx, p->subchannels[p->checking_subchannel], NULL, NULL,
         &p->connectivity_changed);
   }
-  gpr_mu_unlock(&p->mu);
   while (pp != NULL) {
     pending_pick *next = pp->next;
     *pp->target = NULL;
@@ -128,12 +120,11 @@
   }
 }
 
-static void pf_cancel_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
-                           grpc_connected_subchannel **target,
-                           grpc_error *error) {
+static void pf_cancel_pick_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
+                                  grpc_connected_subchannel **target,
+                                  grpc_error *error) {
   pick_first_lb_policy *p = (pick_first_lb_policy *)pol;
   pending_pick *pp;
-  gpr_mu_lock(&p->mu);
   pp = p->pending_picks;
   p->pending_picks = NULL;
   while (pp != NULL) {
@@ -150,17 +141,15 @@
     }
     pp = next;
   }
-  gpr_mu_unlock(&p->mu);
   GRPC_ERROR_UNREF(error);
 }
 
-static void pf_cancel_picks(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
-                            uint32_t initial_metadata_flags_mask,
-                            uint32_t initial_metadata_flags_eq,
-                            grpc_error *error) {
+static void pf_cancel_picks_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
+                                   uint32_t initial_metadata_flags_mask,
+                                   uint32_t initial_metadata_flags_eq,
+                                   grpc_error *error) {
   pick_first_lb_policy *p = (pick_first_lb_policy *)pol;
   pending_pick *pp;
-  gpr_mu_lock(&p->mu);
   pp = p->pending_picks;
   p->pending_picks = NULL;
   while (pp != NULL) {
@@ -177,7 +166,6 @@
     }
     pp = next;
   }
-  gpr_mu_unlock(&p->mu);
   GRPC_ERROR_UNREF(error);
 }
 
@@ -192,63 +180,48 @@
       &p->connectivity_changed);
 }
 
-static void pf_exit_idle(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
+static void pf_exit_idle_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
   pick_first_lb_policy *p = (pick_first_lb_policy *)pol;
-  gpr_mu_lock(&p->mu);
   if (!p->started_picking) {
     start_picking(exec_ctx, p);
   }
-  gpr_mu_unlock(&p->mu);
 }
 
-static int pf_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
-                   const grpc_lb_policy_pick_args *pick_args,
-                   grpc_connected_subchannel **target, void **user_data,
-                   grpc_closure *on_complete) {
+static int pf_pick_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
+                          const grpc_lb_policy_pick_args *pick_args,
+                          grpc_connected_subchannel **target, void **user_data,
+                          grpc_closure *on_complete) {
   pick_first_lb_policy *p = (pick_first_lb_policy *)pol;
   pending_pick *pp;
 
   /* Check atomically for a selected channel */
-  grpc_connected_subchannel *selected = GET_SELECTED(p);
-  if (selected != NULL) {
-    *target = GRPC_CONNECTED_SUBCHANNEL_REF(selected, "picked");
+  if (p->selected != NULL) {
+    *target = GRPC_CONNECTED_SUBCHANNEL_REF(p->selected, "picked");
     return 1;
   }
 
-  /* No subchannel selected yet, so acquire lock and then attempt again */
-  gpr_mu_lock(&p->mu);
-  selected = GET_SELECTED(p);
-  if (selected) {
-    gpr_mu_unlock(&p->mu);
-    *target = GRPC_CONNECTED_SUBCHANNEL_REF(selected, "picked");
-    return 1;
-  } else {
-    if (!p->started_picking) {
-      start_picking(exec_ctx, p);
-    }
-    pp = gpr_malloc(sizeof(*pp));
-    pp->next = p->pending_picks;
-    pp->target = target;
-    pp->initial_metadata_flags = pick_args->initial_metadata_flags;
-    pp->on_complete = on_complete;
-    p->pending_picks = pp;
-    gpr_mu_unlock(&p->mu);
-    return 0;
+  /* No subchannel selected yet, so try again */
+  if (!p->started_picking) {
+    start_picking(exec_ctx, p);
   }
+  pp = gpr_malloc(sizeof(*pp));
+  pp->next = p->pending_picks;
+  pp->target = target;
+  pp->initial_metadata_flags = pick_args->initial_metadata_flags;
+  pp->on_complete = on_complete;
+  p->pending_picks = pp;
+  return 0;
 }
 
-static void destroy_subchannels(grpc_exec_ctx *exec_ctx, void *arg,
-                                grpc_error *error) {
-  pick_first_lb_policy *p = arg;
+static void destroy_subchannels_locked(grpc_exec_ctx *exec_ctx,
+                                       pick_first_lb_policy *p) {
   size_t i;
   size_t num_subchannels = p->num_subchannels;
   grpc_subchannel **subchannels;
 
-  gpr_mu_lock(&p->mu);
   subchannels = p->subchannels;
   p->num_subchannels = 0;
   p->subchannels = NULL;
-  gpr_mu_unlock(&p->mu);
   GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &p->base, "destroy_subchannels");
 
   for (i = 0; i < num_subchannels; i++) {
@@ -258,25 +231,19 @@
   gpr_free(subchannels);
 }
 
-static void pf_connectivity_changed(grpc_exec_ctx *exec_ctx, void *arg,
-                                    grpc_error *error) {
+static void pf_connectivity_changed_locked(grpc_exec_ctx *exec_ctx, void *arg,
+                                           grpc_error *error) {
   pick_first_lb_policy *p = arg;
   grpc_subchannel *selected_subchannel;
   pending_pick *pp;
-  grpc_connected_subchannel *selected;
 
   GRPC_ERROR_REF(error);
 
-  gpr_mu_lock(&p->mu);
-
-  selected = GET_SELECTED(p);
-
   if (p->shutdown) {
-    gpr_mu_unlock(&p->mu);
     GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &p->base, "pick_first_connectivity");
     GRPC_ERROR_UNREF(error);
     return;
-  } else if (selected != NULL) {
+  } else if (p->selected != NULL) {
     if (p->checking_connectivity == GRPC_CHANNEL_TRANSIENT_FAILURE) {
       /* if the selected channel goes bad, we're done */
       p->checking_connectivity = GRPC_CHANNEL_SHUTDOWN;
@@ -286,7 +253,7 @@
                                 "selected_changed");
     if (p->checking_connectivity != GRPC_CHANNEL_SHUTDOWN) {
       grpc_connected_subchannel_notify_on_state_change(
-          exec_ctx, selected, p->base.interested_parties,
+          exec_ctx, p->selected, p->base.interested_parties,
           &p->checking_connectivity, &p->connectivity_changed);
     } else {
       GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &p->base, "pick_first_connectivity");
@@ -301,26 +268,21 @@
                                     GRPC_CHANNEL_READY, GRPC_ERROR_NONE,
                                     "connecting_ready");
         selected_subchannel = p->subchannels[p->checking_subchannel];
-        selected =
-            grpc_subchannel_get_connected_subchannel(selected_subchannel);
-        GPR_ASSERT(selected != NULL);
-        GRPC_CONNECTED_SUBCHANNEL_REF(selected, "picked_first");
+        p->selected = GRPC_CONNECTED_SUBCHANNEL_REF(
+            grpc_subchannel_get_connected_subchannel(selected_subchannel),
+            "picked_first");
         /* drop the pick list: we are connected now */
         GRPC_LB_POLICY_WEAK_REF(&p->base, "destroy_subchannels");
-        gpr_atm_rel_store(&p->selected, (gpr_atm)selected);
-        grpc_closure_sched(exec_ctx,
-                           grpc_closure_create(destroy_subchannels, p,
-                                               grpc_schedule_on_exec_ctx),
-                           GRPC_ERROR_NONE);
+        destroy_subchannels_locked(exec_ctx, p);
         /* update any calls that were waiting for a pick */
         while ((pp = p->pending_picks)) {
           p->pending_picks = pp->next;
-          *pp->target = GRPC_CONNECTED_SUBCHANNEL_REF(selected, "picked");
+          *pp->target = GRPC_CONNECTED_SUBCHANNEL_REF(p->selected, "picked");
           grpc_closure_sched(exec_ctx, pp->on_complete, GRPC_ERROR_NONE);
           gpr_free(pp);
         }
         grpc_connected_subchannel_notify_on_state_change(
-            exec_ctx, selected, p->base.interested_parties,
+            exec_ctx, p->selected, p->base.interested_parties,
             &p->checking_connectivity, &p->connectivity_changed);
         break;
       case GRPC_CHANNEL_TRANSIENT_FAILURE:
@@ -387,48 +349,44 @@
     }
   }
 
-  gpr_mu_unlock(&p->mu);
-
   GRPC_ERROR_UNREF(error);
 }
 
-static grpc_connectivity_state pf_check_connectivity(grpc_exec_ctx *exec_ctx,
-                                                     grpc_lb_policy *pol,
-                                                     grpc_error **error) {
+static grpc_connectivity_state pf_check_connectivity_locked(
+    grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol, grpc_error **error) {
   pick_first_lb_policy *p = (pick_first_lb_policy *)pol;
-  grpc_connectivity_state st;
-  gpr_mu_lock(&p->mu);
-  st = grpc_connectivity_state_get(&p->state_tracker, error);
-  gpr_mu_unlock(&p->mu);
-  return st;
+  return grpc_connectivity_state_get(&p->state_tracker, error);
 }
 
-static void pf_notify_on_state_change(grpc_exec_ctx *exec_ctx,
-                                      grpc_lb_policy *pol,
-                                      grpc_connectivity_state *current,
-                                      grpc_closure *notify) {
+static void pf_notify_on_state_change_locked(grpc_exec_ctx *exec_ctx,
+                                             grpc_lb_policy *pol,
+                                             grpc_connectivity_state *current,
+                                             grpc_closure *notify) {
   pick_first_lb_policy *p = (pick_first_lb_policy *)pol;
-  gpr_mu_lock(&p->mu);
   grpc_connectivity_state_notify_on_state_change(exec_ctx, &p->state_tracker,
                                                  current, notify);
-  gpr_mu_unlock(&p->mu);
 }
 
-static void pf_ping_one(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
-                        grpc_closure *closure) {
+static void pf_ping_one_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
+                               grpc_closure *closure) {
   pick_first_lb_policy *p = (pick_first_lb_policy *)pol;
-  grpc_connected_subchannel *selected = GET_SELECTED(p);
-  if (selected) {
-    grpc_connected_subchannel_ping(exec_ctx, selected, closure);
+  if (p->selected) {
+    grpc_connected_subchannel_ping(exec_ctx, p->selected, closure);
   } else {
     grpc_closure_sched(exec_ctx, closure, GRPC_ERROR_CREATE("Not connected"));
   }
 }
 
 static const grpc_lb_policy_vtable pick_first_lb_policy_vtable = {
-    pf_destroy,     pf_shutdown,           pf_pick,
-    pf_cancel_pick, pf_cancel_picks,       pf_ping_one,
-    pf_exit_idle,   pf_check_connectivity, pf_notify_on_state_change};
+    pf_destroy,
+    pf_shutdown_locked,
+    pf_pick_locked,
+    pf_cancel_pick_locked,
+    pf_cancel_picks_locked,
+    pf_ping_one_locked,
+    pf_exit_idle_locked,
+    pf_check_connectivity_locked,
+    pf_notify_on_state_change_locked};
 
 static void pick_first_factory_ref(grpc_lb_policy_factory *factory) {}
 
@@ -489,10 +447,9 @@
   }
   p->num_subchannels = subchannel_idx;
 
-  grpc_lb_policy_init(&p->base, &pick_first_lb_policy_vtable);
-  grpc_closure_init(&p->connectivity_changed, pf_connectivity_changed, p,
-                    grpc_schedule_on_exec_ctx);
-  gpr_mu_init(&p->mu);
+  grpc_lb_policy_init(&p->base, &pick_first_lb_policy_vtable, args->combiner);
+  grpc_closure_init(&p->connectivity_changed, pf_connectivity_changed_locked, p,
+                    grpc_combiner_scheduler(args->combiner, false));
   return &p->base;
 }
 
diff --git a/src/core/ext/lb_policy/round_robin/round_robin.c b/src/core/ext/lb_policy/round_robin/round_robin.c
index 63e3d03..687df17 100644
--- a/src/core/ext/lb_policy/round_robin/round_robin.c
+++ b/src/core/ext/lb_policy/round_robin/round_robin.c
@@ -67,6 +67,7 @@
 #include "src/core/ext/client_channel/subchannel.h"
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/debug/trace.h"
+#include "src/core/lib/iomgr/combiner.h"
 #include "src/core/lib/iomgr/sockaddr_utils.h"
 #include "src/core/lib/transport/connectivity_state.h"
 #include "src/core/lib/transport/static_metadata.h"
@@ -134,7 +135,6 @@
 struct round_robin_lb_policy {
   /** base policy: must be first */
   grpc_lb_policy base;
-  gpr_mu mu;
 
   /** total number of addresses received at creation time */
   size_t num_addresses;
@@ -293,7 +293,6 @@
 
   grpc_connectivity_state_destroy(exec_ctx, &p->state_tracker);
   gpr_free(p->subchannels);
-  gpr_mu_destroy(&p->mu);
 
   elem = p->ready_list.next;
   while (elem != NULL && elem != &p->ready_list) {
@@ -309,12 +308,11 @@
   gpr_free(p);
 }
 
-static void rr_shutdown(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
+static void rr_shutdown_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
   round_robin_lb_policy *p = (round_robin_lb_policy *)pol;
   pending_pick *pp;
   size_t i;
 
-  gpr_mu_lock(&p->mu);
   if (grpc_lb_round_robin_trace) {
     gpr_log(GPR_DEBUG, "Shutting down Round Robin policy at %p", (void *)pol);
   }
@@ -335,15 +333,13 @@
     grpc_subchannel_notify_on_state_change(exec_ctx, sd->subchannel, NULL, NULL,
                                            &sd->connectivity_changed_closure);
   }
-  gpr_mu_unlock(&p->mu);
 }
 
-static void rr_cancel_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
-                           grpc_connected_subchannel **target,
-                           grpc_error *error) {
+static void rr_cancel_pick_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
+                                  grpc_connected_subchannel **target,
+                                  grpc_error *error) {
   round_robin_lb_policy *p = (round_robin_lb_policy *)pol;
   pending_pick *pp;
-  gpr_mu_lock(&p->mu);
   pp = p->pending_picks;
   p->pending_picks = NULL;
   while (pp != NULL) {
@@ -360,17 +356,15 @@
     }
     pp = next;
   }
-  gpr_mu_unlock(&p->mu);
   GRPC_ERROR_UNREF(error);
 }
 
-static void rr_cancel_picks(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
-                            uint32_t initial_metadata_flags_mask,
-                            uint32_t initial_metadata_flags_eq,
-                            grpc_error *error) {
+static void rr_cancel_picks_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
+                                   uint32_t initial_metadata_flags_mask,
+                                   uint32_t initial_metadata_flags_eq,
+                                   grpc_error *error) {
   round_robin_lb_policy *p = (round_robin_lb_policy *)pol;
   pending_pick *pp;
-  gpr_mu_lock(&p->mu);
   pp = p->pending_picks;
   p->pending_picks = NULL;
   while (pp != NULL) {
@@ -388,11 +382,11 @@
     }
     pp = next;
   }
-  gpr_mu_unlock(&p->mu);
   GRPC_ERROR_UNREF(error);
 }
 
-static void start_picking(grpc_exec_ctx *exec_ctx, round_robin_lb_policy *p) {
+static void start_picking_locked(grpc_exec_ctx *exec_ctx,
+                                 round_robin_lb_policy *p) {
   size_t i;
   p->started_picking = 1;
 
@@ -411,23 +405,20 @@
   }
 }
 
-static void rr_exit_idle(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
+static void rr_exit_idle_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol) {
   round_robin_lb_policy *p = (round_robin_lb_policy *)pol;
-  gpr_mu_lock(&p->mu);
   if (!p->started_picking) {
-    start_picking(exec_ctx, p);
+    start_picking_locked(exec_ctx, p);
   }
-  gpr_mu_unlock(&p->mu);
 }
 
-static int rr_pick(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
-                   const grpc_lb_policy_pick_args *pick_args,
-                   grpc_connected_subchannel **target, void **user_data,
-                   grpc_closure *on_complete) {
+static int rr_pick_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
+                          const grpc_lb_policy_pick_args *pick_args,
+                          grpc_connected_subchannel **target, void **user_data,
+                          grpc_closure *on_complete) {
   round_robin_lb_policy *p = (round_robin_lb_policy *)pol;
   pending_pick *pp;
   ready_list *selected;
-  gpr_mu_lock(&p->mu);
 
   if (grpc_lb_round_robin_trace) {
     gpr_log(GPR_INFO, "Round Robin %p trying to pick", (void *)pol);
@@ -449,12 +440,11 @@
     }
     /* only advance the last picked pointer if the selection was used */
     advance_last_picked_locked(p);
-    gpr_mu_unlock(&p->mu);
     return 1;
   } else {
     /* no pick currently available. Save for later in list of pending picks */
     if (!p->started_picking) {
-      start_picking(exec_ctx, p);
+      start_picking_locked(exec_ctx, p);
     }
     pp = gpr_malloc(sizeof(*pp));
     pp->next = p->pending_picks;
@@ -463,7 +453,6 @@
     pp->initial_metadata_flags = pick_args->initial_metadata_flags;
     pp->user_data = user_data;
     p->pending_picks = pp;
-    gpr_mu_unlock(&p->mu);
     return 0;
   }
 }
@@ -538,17 +527,15 @@
   return sd->curr_connectivity_state;
 }
 
-static void rr_connectivity_changed(grpc_exec_ctx *exec_ctx, void *arg,
-                                    grpc_error *error) {
+static void rr_connectivity_changed_locked(grpc_exec_ctx *exec_ctx, void *arg,
+                                           grpc_error *error) {
   subchannel_data *sd = arg;
   round_robin_lb_policy *p = sd->policy;
   pending_pick *pp;
 
   GRPC_ERROR_REF(error);
-  gpr_mu_lock(&p->mu);
 
   if (p->shutdown) {
-    gpr_mu_unlock(&p->mu);
     GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &p->base, "rr_connectivity");
     GRPC_ERROR_UNREF(error);
     return;
@@ -645,56 +632,51 @@
       GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &p->base, "rr_connectivity");
       break;
   }
-  gpr_mu_unlock(&p->mu);
   GRPC_ERROR_UNREF(error);
 }
 
-static grpc_connectivity_state rr_check_connectivity(grpc_exec_ctx *exec_ctx,
-                                                     grpc_lb_policy *pol,
-                                                     grpc_error **error) {
+static grpc_connectivity_state rr_check_connectivity_locked(
+    grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol, grpc_error **error) {
   round_robin_lb_policy *p = (round_robin_lb_policy *)pol;
-  grpc_connectivity_state st;
-  gpr_mu_lock(&p->mu);
-  st = grpc_connectivity_state_get(&p->state_tracker, error);
-  gpr_mu_unlock(&p->mu);
-  return st;
+  return grpc_connectivity_state_get(&p->state_tracker, error);
 }
 
-static void rr_notify_on_state_change(grpc_exec_ctx *exec_ctx,
-                                      grpc_lb_policy *pol,
-                                      grpc_connectivity_state *current,
-                                      grpc_closure *notify) {
+static void rr_notify_on_state_change_locked(grpc_exec_ctx *exec_ctx,
+                                             grpc_lb_policy *pol,
+                                             grpc_connectivity_state *current,
+                                             grpc_closure *notify) {
   round_robin_lb_policy *p = (round_robin_lb_policy *)pol;
-  gpr_mu_lock(&p->mu);
   grpc_connectivity_state_notify_on_state_change(exec_ctx, &p->state_tracker,
                                                  current, notify);
-  gpr_mu_unlock(&p->mu);
 }
 
-static void rr_ping_one(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
-                        grpc_closure *closure) {
+static void rr_ping_one_locked(grpc_exec_ctx *exec_ctx, grpc_lb_policy *pol,
+                               grpc_closure *closure) {
   round_robin_lb_policy *p = (round_robin_lb_policy *)pol;
   ready_list *selected;
   grpc_connected_subchannel *target;
-  gpr_mu_lock(&p->mu);
   if ((selected = peek_next_connected_locked(p))) {
-    gpr_mu_unlock(&p->mu);
     target = GRPC_CONNECTED_SUBCHANNEL_REF(
         grpc_subchannel_get_connected_subchannel(selected->subchannel),
         "rr_picked");
     grpc_connected_subchannel_ping(exec_ctx, target, closure);
     GRPC_CONNECTED_SUBCHANNEL_UNREF(exec_ctx, target, "rr_picked");
   } else {
-    gpr_mu_unlock(&p->mu);
     grpc_closure_sched(exec_ctx, closure,
                        GRPC_ERROR_CREATE("Round Robin not connected"));
   }
 }
 
 static const grpc_lb_policy_vtable round_robin_lb_policy_vtable = {
-    rr_destroy,     rr_shutdown,           rr_pick,
-    rr_cancel_pick, rr_cancel_picks,       rr_ping_one,
-    rr_exit_idle,   rr_check_connectivity, rr_notify_on_state_change};
+    rr_destroy,
+    rr_shutdown_locked,
+    rr_pick_locked,
+    rr_cancel_pick_locked,
+    rr_cancel_picks_locked,
+    rr_ping_one_locked,
+    rr_exit_idle_locked,
+    rr_check_connectivity_locked,
+    rr_notify_on_state_change_locked};
 
 static void round_robin_factory_ref(grpc_lb_policy_factory *factory) {}
 
@@ -762,7 +744,8 @@
       }
       ++subchannel_idx;
       grpc_closure_init(&sd->connectivity_changed_closure,
-                        rr_connectivity_changed, sd, grpc_schedule_on_exec_ctx);
+                        rr_connectivity_changed_locked, sd,
+                        grpc_combiner_scheduler(args->combiner, false));
     }
   }
   if (subchannel_idx == 0) {
@@ -779,7 +762,7 @@
   p->ready_list.next = NULL;
   p->ready_list_last_pick = &p->ready_list;
 
-  grpc_lb_policy_init(&p->base, &round_robin_lb_policy_vtable);
+  grpc_lb_policy_init(&p->base, &round_robin_lb_policy_vtable, args->combiner);
   grpc_connectivity_state_init(&p->state_tracker, GRPC_CHANNEL_IDLE,
                                "round_robin");
 
@@ -787,7 +770,6 @@
     gpr_log(GPR_DEBUG, "Created RR policy at %p with %lu subchannels",
             (void *)p, (unsigned long)p->num_subchannels);
   }
-  gpr_mu_init(&p->mu);
   return &p->base;
 }
 
diff --git a/src/core/lib/iomgr/resolve_address_uv.c b/src/core/lib/iomgr/resolve_address_uv.c
index 9b5f320..79ff910 100644
--- a/src/core/lib/iomgr/resolve_address_uv.c
+++ b/src/core/lib/iomgr/resolve_address_uv.c
@@ -113,14 +113,15 @@
   /* parse name, splitting it into host and port parts */
   grpc_error *error;
   gpr_split_host_port(name, host, port);
-  if (host == NULL) {
+  if (*host == NULL) {
     char *msg;
     gpr_asprintf(&msg, "unparseable host:port: '%s'", name);
     error = GRPC_ERROR_CREATE(msg);
     gpr_free(msg);
     return error;
   }
-  if (port == NULL) {
+  if (*port == NULL) {
+    // TODO(murgatroid99): add tests for this case
     if (default_port == NULL) {
       char *msg;
       gpr_asprintf(&msg, "no port in name '%s'", name);
diff --git a/src/core/lib/iomgr/socket_utils_windows.c b/src/core/lib/iomgr/socket_utils_windows.c
index 628ad4a..5bbe8fa 100644
--- a/src/core/lib/iomgr/socket_utils_windows.c
+++ b/src/core/lib/iomgr/socket_utils_windows.c
@@ -41,8 +41,12 @@
 #include <grpc/support/log.h>
 
 const char *grpc_inet_ntop(int af, const void *src, char *dst, size_t size) {
+#ifdef GPR_WIN_INET_NTOP
+  return inet_ntop(af, src, dst, size);
+#else
   /* Windows InetNtopA wants a mutable ip pointer */
   return InetNtopA(af, (void *)src, dst, size);
+#endif /* GPR_WIN_INET_NTOP */
 }
 
 #endif /* GRPC_WINDOWS_SOCKETUTILS */
diff --git a/src/core/lib/iomgr/tcp_client_uv.c b/src/core/lib/iomgr/tcp_client_uv.c
index 5225a54..3de0795 100644
--- a/src/core/lib/iomgr/tcp_client_uv.c
+++ b/src/core/lib/iomgr/tcp_client_uv.c
@@ -46,6 +46,8 @@
 #include "src/core/lib/iomgr/tcp_uv.h"
 #include "src/core/lib/iomgr/timer.h"
 
+extern int grpc_tcp_trace;
+
 typedef struct grpc_uv_tcp_connect {
   uv_connect_t connect_req;
   grpc_timer alarm;
@@ -70,6 +72,12 @@
                            grpc_error *error) {
   int done;
   grpc_uv_tcp_connect *connect = acp;
+  if (grpc_tcp_trace) {
+    const char *str = grpc_error_string(error);
+    gpr_log(GPR_DEBUG, "CLIENT_CONNECT: %s: on_alarm: error=%s",
+            connect->addr_name, str);
+    grpc_error_free_string(str);
+  }
   if (error == GRPC_ERROR_NONE) {
     /* error == NONE implies that the timer ran out, and wasn't cancelled. If
        it was cancelled, then the handler that cancelled it also should close
@@ -145,6 +153,12 @@
   connect->resource_quota = resource_quota;
   uv_tcp_init(uv_default_loop(), connect->tcp_handle);
   connect->connect_req.data = connect;
+
+  if (grpc_tcp_trace) {
+    gpr_log(GPR_DEBUG, "CLIENT_CONNECT: %s: asynchronously connecting",
+            connect->addr_name);
+  }
+
   // TODO(murgatroid99): figure out what the return value here means
   uv_tcp_connect(&connect->connect_req, connect->tcp_handle,
                  (const struct sockaddr *)resolved_addr->addr,
diff --git a/src/cpp/server/server_cc.cc b/src/cpp/server/server_cc.cc
index 150c5a5..9e11a8a 100644
--- a/src/cpp/server/server_cc.cc
+++ b/src/cpp/server/server_cc.cc
@@ -189,8 +189,7 @@
     explicit CallData(Server* server, SyncRequest* mrd)
         : cq_(mrd->cq_),
           call_(mrd->call_, server, &cq_, server->max_receive_message_size()),
-          ctx_(mrd->deadline_, mrd->request_metadata_.metadata,
-               mrd->request_metadata_.count),
+          ctx_(mrd->deadline_, &mrd->request_metadata_),
           has_request_payload_(mrd->has_request_payload_),
           request_payload_(mrd->request_payload_),
           method_(mrd->method_) {
diff --git a/src/cpp/server/server_context.cc b/src/cpp/server/server_context.cc
index 6edbc90..05c05c8 100644
--- a/src/cpp/server/server_context.cc
+++ b/src/cpp/server/server_context.cc
@@ -33,7 +33,9 @@
 
 #include <grpc++/server_context.h>
 
+#include <algorithm>
 #include <mutex>
+#include <utility>
 
 #include <grpc++/completion_queue.h>
 #include <grpc++/impl/call.h>
@@ -133,8 +135,7 @@
       sent_initial_metadata_(false),
       compression_level_set_(false) {}
 
-ServerContext::ServerContext(gpr_timespec deadline, grpc_metadata* metadata,
-                             size_t metadata_count)
+ServerContext::ServerContext(gpr_timespec deadline, grpc_metadata_array* arr)
     : completion_op_(nullptr),
       has_notify_when_done_tag_(false),
       async_notify_when_done_tag_(nullptr),
@@ -143,12 +144,8 @@
       cq_(nullptr),
       sent_initial_metadata_(false),
       compression_level_set_(false) {
-  for (size_t i = 0; i < metadata_count; i++) {
-    client_metadata_.map()->insert(
-        std::pair<grpc::string_ref, grpc::string_ref>(
-            StringRefFromSlice(&metadata[i].key),
-            StringRefFromSlice(&metadata[i].value)));
-  }
+  std::swap(*client_metadata_.arr(), *arr);
+  client_metadata_.FillMap();
 }
 
 ServerContext::~ServerContext() {
diff --git a/src/csharp/README.md b/src/csharp/README.md
index 8468eb9..a21b72f 100644
--- a/src/csharp/README.md
+++ b/src/csharp/README.md
@@ -7,19 +7,19 @@
 SUPPORTED PLATFORMS
 ------------------
 
+- [.NET Core](https://dotnet.github.io/) on Linux, Windows and Mac OS X 
 - .NET Framework 4.5+ (Windows)
-- [.NET Core](https://dotnet.github.io/) on Linux, Windows and Mac OS X (starting from version 1.0.1)
 - Mono 4+ on Linux, Windows and Mac OS X
 
-
 PREREQUISITES
 --------------
 
+When using gRPC C# under .NET Core you only need to [install .NET Core](https://www.microsoft.com/net/core).
+
 - Windows: .NET Framework 4.5+, Visual Studio 2013 or 2015
 - Linux: Mono 4+, MonoDevelop 5.9+ (with NuGet add-in installed)
 - Mac OS X: Xamarin Studio 5.9+
 
-
 HOW TO USE
 --------------
 
@@ -27,7 +27,7 @@
 
 - Open Visual Studio / MonoDevelop / Xamarin Studio and start a new project/solution.
 
-- Add the [Grpc](https://www.nuget.org/packages/Grpc/) NuGet package as a dependency (Project options -> Manage NuGet Packages).
+- Add the [Grpc](https://www.nuget.org/packages/Grpc/) NuGet package as a dependency (Project options -> Manage NuGet Packages). 
 
 - To be able to generate code from Protocol Buffer (`.proto`) file definitions, add the [Grpc.Tools](https://www.nuget.org/packages/Grpc.Tools/) NuGet package that contains Protocol Buffers compiler (_protoc_) and the gRPC _protoc_ plugin.
 
@@ -71,23 +71,10 @@
 - [Helloworld Example][]
 - [RouteGuide Tutorial][]
 
-CONTENTS
---------
+PERFORMANCE
+-----------
 
-- ext:
-  The extension library that wraps C API to be more digestible by C#.
-- Grpc.Auth:
-  gRPC OAuth2/JWT support.
-- Grpc.Core:
-  The main gRPC C# library.
-- Grpc.Examples:
-  API examples for math.proto
-- Grpc.Examples.MathClient:
-  An example client that sends requests to math server.
-- Grpc.Examples.MathServer:
-  An example server that implements a simple math service.
-- Grpc.IntegrationTesting:
-  Cross-language gRPC implementation testing (interop testing).
+For best gRPC C# performance, use [.NET Core](https://dotnet.github.io/) and the Server GC mode `"System.GC.Server": true` for your applications.
 
 THE NATIVE DEPENDENCY
 ---------------
diff --git a/src/node/ext/completion_queue_threadpool.cc b/src/node/ext/completion_queue_threadpool.cc
index 6302e7a..4881542 100644
--- a/src/node/ext/completion_queue_threadpool.cc
+++ b/src/node/ext/completion_queue_threadpool.cc
@@ -78,6 +78,8 @@
   void HandleErrorCallback();
 
  private:
+  static void TryAddWorker();
+
   grpc_event result;
 
   static grpc_completion_queue *queue;
@@ -118,20 +120,21 @@
 
 grpc_completion_queue *CompletionQueueAsyncWorker::GetQueue() { return queue; }
 
-void CompletionQueueAsyncWorker::Next() {
-#ifndef GRPC_UV
-  Nan::HandleScope scope;
-  if (current_threads < max_queue_threads) {
+void CompletionQueueAsyncWorker::TryAddWorker() {
+  if (current_threads < max_queue_threads && waiting_next_calls > 0) {
     current_threads += 1;
+    waiting_next_calls -= 1;
     CompletionQueueAsyncWorker *worker = new CompletionQueueAsyncWorker();
     Nan::AsyncQueueWorker(worker);
-  } else {
-    waiting_next_calls += 1;
   }
   GPR_ASSERT(current_threads <= max_queue_threads);
   GPR_ASSERT((current_threads == max_queue_threads) ||
              (waiting_next_calls == 0));
-#endif
+}
+
+void CompletionQueueAsyncWorker::Next() {
+  waiting_next_calls += 1;
+  TryAddWorker();
 }
 
 void CompletionQueueAsyncWorker::Init(Local<Object> exports) {
@@ -143,17 +146,8 @@
 
 void CompletionQueueAsyncWorker::HandleOKCallback() {
   Nan::HandleScope scope;
-  if (waiting_next_calls > 0) {
-    waiting_next_calls -= 1;
-    // Old worker removed, new worker added. current_threads += 0
-    CompletionQueueAsyncWorker *worker = new CompletionQueueAsyncWorker();
-    Nan::AsyncQueueWorker(worker);
-  } else {
-    current_threads -= 1;
-  }
-  GPR_ASSERT(current_threads <= max_queue_threads);
-  GPR_ASSERT((current_threads == max_queue_threads) ||
-             (waiting_next_calls == 0));
+  current_threads -= 1;
+  TryAddWorker();
   Nan::Callback *callback = GetTagCallback(result.tag);
   Local<Value> argv[] = {Nan::Null(), GetTagNodeValue(result.tag)};
   callback->Call(2, argv);
@@ -162,18 +156,9 @@
 }
 
 void CompletionQueueAsyncWorker::HandleErrorCallback() {
-  if (waiting_next_calls > 0) {
-    waiting_next_calls -= 1;
-    // Old worker removed, new worker added. current_threads += 0
-    CompletionQueueAsyncWorker *worker = new CompletionQueueAsyncWorker();
-    Nan::AsyncQueueWorker(worker);
-  } else {
-    current_threads -= 1;
-  }
-  GPR_ASSERT(current_threads <= max_queue_threads);
-  GPR_ASSERT((current_threads == max_queue_threads) ||
-             (waiting_next_calls == 0));
   Nan::HandleScope scope;
+  current_threads -= 1;
+  TryAddWorker();
   Nan::Callback *callback = GetTagCallback(result.tag);
   Local<Value> argv[] = {Nan::Error(ErrorMessage())};
 
@@ -189,6 +174,7 @@
 }
 
 void CompletionQueueNext() {
+  gpr_log(GPR_DEBUG, "Called CompletionQueueNext");
   CompletionQueueAsyncWorker::Next();
 }
 
diff --git a/src/node/src/client.js b/src/node/src/client.js
index 134ef23..44081a3 100644
--- a/src/node/src/client.js
+++ b/src/node/src/client.js
@@ -108,7 +108,7 @@
        but passing an object that causes a serialization failure is a misuse
        of the API anyway, so that's OK. The primary purpose here is to give the
        programmer a useful error and to stop the stream properly */
-    this.call.cancelWithStatus(grpc.status.INTERNAL, "Serialization failure");
+    this.call.cancelWithStatus(grpc.status.INTERNAL, 'Serialization failure');
     callback(e);
   }
   if (_.isFinite(encoding)) {
@@ -831,13 +831,12 @@
  */
 exports.makeProtobufClientConstructor =  function(service, options) {
   var method_attrs = common.getProtobufServiceAttrs(service, options);
-  var deprecatedArgumentOrder = false;
-  if (options) {
-    deprecatedArgumentOrder = options.deprecatedArgumentOrder;
+  if (!options) {
+    options = {deprecatedArgumentOrder: false};
   }
   var Client = exports.makeClientConstructor(
       method_attrs, common.fullyQualifiedName(service),
-      deprecatedArgumentOrder);
+      options);
   Client.service = service;
   Client.service.grpc_options = options;
   return Client;
diff --git a/src/node/src/server.js b/src/node/src/server.js
index da9c6b2..8a7eff5 100644
--- a/src/node/src/server.js
+++ b/src/node/src/server.js
@@ -121,20 +121,20 @@
   if (metadata) {
     statusMetadata = metadata;
   }
-  status.metadata = statusMetadata._getCoreRepresentation();
-  if (!call.metadataSent) {
-    end_batch[grpc.opType.SEND_INITIAL_METADATA] =
-        (new Metadata())._getCoreRepresentation();
-    call.metadataSent = true;
-  }
   var message;
   try {
     message = serialize(value);
   } catch (e) {
     e.code = grpc.status.INTERNAL;
-    handleError(e);
+    handleError(call, e);
     return;
   }
+  status.metadata = statusMetadata._getCoreRepresentation();
+  if (!call.metadataSent) {
+    end_batch[grpc.opType.SEND_INITIAL_METADATA] =
+        (new Metadata())._getCoreRepresentation();
+    call.metadataSent = true;
+  }
   message.grpcWriteFlags = flags;
   end_batch[grpc.opType.SEND_MESSAGE] = message;
   end_batch[grpc.opType.SEND_STATUS_FROM_SERVER] = status;
@@ -280,11 +280,6 @@
   /* jshint validthis: true */
   var batch = {};
   var self = this;
-  if (!this.call.metadataSent) {
-    batch[grpc.opType.SEND_INITIAL_METADATA] =
-        (new Metadata())._getCoreRepresentation();
-    this.call.metadataSent = true;
-  }
   var message;
   try {
     message = this.serialize(chunk);
@@ -293,6 +288,11 @@
     callback(e);
     return;
   }
+  if (!this.call.metadataSent) {
+    batch[grpc.opType.SEND_INITIAL_METADATA] =
+        (new Metadata())._getCoreRepresentation();
+    this.call.metadataSent = true;
+  }
   if (_.isFinite(encoding)) {
     /* Attach the encoding if it is a finite number. This is the closest we
      * can get to checking that it is valid flags */
@@ -728,11 +728,17 @@
  *     method implementation for the provided service.
  */
 Server.prototype.addService = function(service, implementation) {
+  if (!_.isObjectLike(service) || !_.isObjectLike(implementation)) {
+    throw new Error('addService requires two objects as arguments');
+  }
+  if (_.keys(service).length === 0) {
+    throw new Error('Cannot add an empty service to a server');
+  }
   if (this.started) {
     throw new Error('Can\'t add a service to a started server.');
   }
   var self = this;
-  _.each(service, function(attrs, name) {
+  _.forOwn(service, function(attrs, name) {
     var method_type;
     if (attrs.requestStream) {
       if (attrs.responseStream) {
diff --git a/src/node/test/surface_test.js b/src/node/test/surface_test.js
index e429a36..2636ea8 100644
--- a/src/node/test/surface_test.js
+++ b/src/node/test/surface_test.js
@@ -607,6 +607,113 @@
     call.end();
   });
 });
+describe('Server serialization failure handling', function() {
+  function serializeFail(obj) {
+    throw new Error('Serialization failed');
+  }
+  var client;
+  var server;
+  before(function() {
+    var test_proto = ProtoBuf.loadProtoFile(__dirname + '/test_service.proto');
+    var test_service = test_proto.lookup('TestService');
+    var malformed_test_service = {
+      unary: {
+        path: '/TestService/Unary',
+        requestStream: false,
+        responseStream: false,
+        requestDeserialize: _.identity,
+        responseSerialize: serializeFail
+      },
+      clientStream: {
+        path: '/TestService/ClientStream',
+        requestStream: true,
+        responseStream: false,
+        requestDeserialize: _.identity,
+        responseSerialize: serializeFail
+      },
+      serverStream: {
+        path: '/TestService/ServerStream',
+        requestStream: false,
+        responseStream: true,
+        requestDeserialize: _.identity,
+        responseSerialize: serializeFail
+      },
+      bidiStream: {
+        path: '/TestService/BidiStream',
+        requestStream: true,
+        responseStream: true,
+        requestDeserialize: _.identity,
+        responseSerialize: serializeFail
+      }
+    };
+    server = new grpc.Server();
+    server.addService(malformed_test_service, {
+      unary: function(call, cb) {
+        cb(null, {});
+      },
+      clientStream: function(stream, cb) {
+        stream.on('data', function() {/* Ignore requests */});
+        stream.on('end', function() {
+          cb(null, {});
+        });
+      },
+      serverStream: function(stream) {
+        stream.write({});
+        stream.end();
+      },
+      bidiStream: function(stream) {
+        stream.on('data', function() {
+          // Ignore requests
+          stream.write({});
+        });
+        stream.on('end', function() {
+          stream.end();
+        });
+      }
+    });
+    var port = server.bind('localhost:0', server_insecure_creds);
+    var Client = surface_client.makeProtobufClientConstructor(test_service);
+    client = new Client('localhost:' + port, grpc.credentials.createInsecure());
+    server.start();
+  });
+  after(function() {
+    server.forceShutdown();
+  });
+  it('should get an INTERNAL status with a unary call', function(done) {
+    client.unary({}, function(err, data) {
+      assert(err);
+      assert.strictEqual(err.code, grpc.status.INTERNAL);
+      done();
+    });
+  });
+  it('should get an INTERNAL status with a client stream call', function(done) {
+    var call = client.clientStream(function(err, data) {
+      assert(err);
+      assert.strictEqual(err.code, grpc.status.INTERNAL);
+      done();
+    });
+    call.write({});
+    call.end();
+  });
+  it('should get an INTERNAL status with a server stream call', function(done) {
+    var call = client.serverStream({});
+    call.on('data', function(){});
+    call.on('error', function(err) {
+      assert.strictEqual(err.code, grpc.status.INTERNAL);
+      done();
+    });
+  });
+  it('should get an INTERNAL status with a bidi stream call', function(done) {
+    var call = client.bidiStream();
+    call.on('data', function(){});
+    call.on('error', function(err) {
+      assert.strictEqual(err.code, grpc.status.INTERNAL);
+      done();
+    });
+    call.write({});
+    call.end();
+  });
+});
 describe('Other conditions', function() {
   var test_service;
   var Client;
diff --git a/src/python/grpcio/grpc/_channel.py b/src/python/grpcio/grpc/_channel.py
index e602f39..af86f5e 100644
--- a/src/python/grpcio/grpc/_channel.py
+++ b/src/python/grpcio/grpc/_channel.py
@@ -39,7 +39,7 @@
 from grpc._cython import cygrpc
 from grpc.framework.foundation import callable_util
 
-_USER_AGENT = 'Python-gRPC-{}'.format(_grpcio_metadata.__version__)
+_USER_AGENT = 'grpc-python/{}'.format(_grpcio_metadata.__version__)
 
 _EMPTY_FLAGS = 0
 _INFINITE_FUTURE = cygrpc.Timespec(float('+inf'))
diff --git a/src/python/grpcio_tests/tests/unit/_metadata_test.py b/src/python/grpcio_tests/tests/unit/_metadata_test.py
index 53fe7ba..035d87e 100644
--- a/src/python/grpcio_tests/tests/unit/_metadata_test.py
+++ b/src/python/grpcio_tests/tests/unit/_metadata_test.py
@@ -32,7 +32,7 @@
 import weakref
 
 import grpc
-from grpc import _grpcio_metadata
+from grpc import _channel
 from grpc.framework.foundation import logging_pool
 
 from tests.unit import test_common
@@ -49,8 +49,6 @@
 _STREAM_UNARY = '/test/StreamUnary'
 _STREAM_STREAM = '/test/StreamStream'
 
-_USER_AGENT = 'Python-gRPC-{}'.format(_grpcio_metadata.__version__)
-
 _CLIENT_METADATA = (('client-md-key', 'client-md-key'),
                     ('client-md-key-bin', b'\x00\x01'))
 
@@ -76,7 +74,7 @@
             _CLIENT_METADATA, servicer_context.invocation_metadata()))
     test.assertTrue(
         user_agent(servicer_context.invocation_metadata())
-        .startswith('primary-agent ' + _USER_AGENT))
+        .startswith('primary-agent ' + _channel._USER_AGENT))
     test.assertTrue(
         user_agent(servicer_context.invocation_metadata())
         .endswith('secondary-agent'))
diff --git a/src/ruby/ext/grpc/extconf.rb b/src/ruby/ext/grpc/extconf.rb
index 66c54aa..b379664 100644
--- a/src/ruby/ext/grpc/extconf.rb
+++ b/src/ruby/ext/grpc/extconf.rb
@@ -102,7 +102,6 @@
 $CFLAGS << ' -Wall '
 $CFLAGS << ' -Wextra '
 $CFLAGS << ' -pedantic '
-$CFLAGS << ' -Werror '
 $CFLAGS << ' -Wno-format '
 
 output = File.join('grpc', 'grpc_c')
diff --git a/templates/Makefile.template b/templates/Makefile.template
index 10d7861..f81d643 100644
--- a/templates/Makefile.template
+++ b/templates/Makefile.template
@@ -1492,7 +1492,7 @@
     out_mingbase = '$(LIBDIR)/$(CONFIG)/' + lib.name + '$(SHARED_VERSION_' + lang_to_var[lib.language] + ')'
     out_libbase = '$(LIBDIR)/$(CONFIG)/lib' + lib.name + '$(SHARED_VERSION_' + lang_to_var[lib.language] + ')'
 
-    common = '$(LIB' + lib.name.upper() + '_OBJS) $(LDLIBS)'
+    common = '$(LIB' + lib.name.upper() + '_OBJS)'
 
     link_libs = ''
     lib_deps = ' $(ZLIB_DEP)'
@@ -1542,6 +1542,8 @@
     ldflags = '$(LDFLAGS)'
     if lib.get('LDFLAGS', None):
       ldflags += ' ' + lib['LDFLAGS']
+
+    common = common + ' $(LDLIBS)'
   %>
 
   % if lib.build == "all":
diff --git a/templates/binding.gyp.template b/templates/binding.gyp.template
index 851effc..4b2f6ac 100644
--- a/templates/binding.gyp.template
+++ b/templates/binding.gyp.template
@@ -53,7 +53,9 @@
       'conditions': [
         ['runtime=="node"', {
           'defines': [
-            'GRPC_UV'
+            # Disabling this while bugs are ironed out. Uncomment this to
+            # re-enable libuv integration in C core.
+            # 'GRPC_UV'
           ]
         }],
         ['OS!="win" and runtime=="electron"', {
diff --git a/templates/grpc.gemspec.template b/templates/grpc.gemspec.template
index 82fbb69..462ea52 100644
--- a/templates/grpc.gemspec.template
+++ b/templates/grpc.gemspec.template
@@ -29,7 +29,7 @@
     s.require_paths = %w( src/ruby/bin src/ruby/lib src/ruby/pb )
     s.platform      = Gem::Platform::RUBY
 
-    s.add_dependency 'google-protobuf', '~> 3.1.0'
+    s.add_dependency 'google-protobuf', '~> 3.1'
     s.add_dependency 'googleauth',      '~> 0.5.1'
 
     s.add_development_dependency 'bundler',            '~> 1.9'
@@ -37,7 +37,7 @@
     s.add_development_dependency 'logging',            '~> 2.0'
     s.add_development_dependency 'simplecov',          '~> 0.9'
     s.add_development_dependency 'rake',               '~> 10.4'
-    s.add_development_dependency 'rake-compiler',      '~> 0.9'
+    s.add_development_dependency 'rake-compiler',      '~> 1.0'
     s.add_development_dependency 'rake-compiler-dock', '~> 0.5.1'
     s.add_development_dependency 'rspec',              '~> 3.2'
     s.add_development_dependency 'rubocop',            '~> 0.30.0'
diff --git a/third_party/rake-compiler-dock/Dockerfile b/third_party/rake-compiler-dock/Dockerfile
index c7a6657..475c6a8 100644
--- a/third_party/rake-compiler-dock/Dockerfile
+++ b/third_party/rake-compiler-dock/Dockerfile
@@ -26,76 +26,77 @@
         rvmsudo rvm cleanup all "
 
 # Regenerate the following using build.sh if the build folder changes.
-RUN echo \
-H4sIAJSZulYAA+07a1fbSLL5evUragxnbAdLtvwEApnJAMmwN68DJHPvGbLattSyNZYlbXfLhpuw\
-v/1WtSS/gBB2EnZn1n3AbvWjqrqqurqq1O6nQejVH33T0sDS63Xo2+51GovfRXlkN7uddrPd67a7\
-jxq23Wy2HkHn25KVlVQqJgAeJcEFDz8z7q7+P2jpa/nLYOBPLfcb4SABd7vt2+Rvd5ur8m92Gp1H\
-0PhG9CyV/3D51x8b8BjOhoGERMQDwcYwZJEXcgmnxy+OX58BPoEfiykTnoRAgYqxKVZDLmiGy6W0\
-CMSxAoQRRIpHHvdoVJ+DSCNgEt4eH4JNo2jgYeyOcC6xXckCBKKbBmoIJS/rxYmlpZnwJoKXQZRe\
-1ABRg8d9loYKUHEjFuYkC6IzmwLYHguEyqLLfFBG5hnSzXEYhwMlQvMA2IgVKyX69TQPEgSW46Bp\
-dcPYCCI3TD0Oexk4a/h0se1S1tVlwuX15ikLFLUayBtIAg/2ofHEMCZx4BkZ3Q5CpM4KfRD0dFw1\
-PhoAgV/BCVWsAYyCMKSnWk5t9YlxlcEcsyDSU5kYuDVwh6jPj7E++fVDlaBIJVJXA2auCuIIIj51\
-suoTQkJIFVOpRMpMG0kDqD+GU64gTTSzMwAp8gylKhPuBv6l7kBAkAGyiEewANmSzCmksg9L6ySk\
-WOPjRF1KxFL5fnnamMlR9ck1aH7IBjJnHiysppLxowYLYGpQIf4+rjaqenTGdhT7qKIh54z9qDlL\
-Aqp8n7FA9wIIjsuN4Jej/zk+Oz17dvbutLLQf8VDybO5M8bxC+5Okopmu/0BiclrOUDUJxGLSomG\
-lZaRZCA0XJToQ+//zP4nTLlDLr+RH3D/8x8fmuvz/yHKsvxF2r80bWvb6plJq9f+Svpwf/m3e73e\
-Wv4PUT4v/yhOLN33u3Dc4f817Ia9Iv9ut9Fe+38PUbzA98E0B+jYsbobR34woIO+P6+jj+HxC+h0\
-7E6P+ZbV7bYavM/Axk3d6Tz4gbUuX7XcsP+bVstqfE1X4J+w/82evbb/D1FulX8UOxJDOT8I+e89\
-Au6y/+1ua0X+vW6jubb/D1G+2P7zPm95265lsVar2++1CvtvmubiTGNra2tp9o8/YlC5vdNu1Xqw\
-lVW6gI1eDLsUBjHX8SPHdVD/3JHjp5ELpc2Xx6+PXr8pQalQQaziQHeiB8wUs2RgJAeKSwWli82b\
-BmBkdnHJ5RMKV6MMocsUPH1KBGKAj/E67O05zw6O3jw3zA1sCSIOPz97f+ScHr0+fH788ghsA/IB\
-YIAf/LlOvBv9vx2r9S+2/63G2v4/SLlV/g9n/+2m3b5u/9f53wcpX2z/t3e2e60G2n/X591m5372\
-v93d6Wj7n1ewkVK1ZPvJ4AcR+OPY0znOZKATcm39SXk7ytqBTNg0moC8lC4LQ3CcouYORRwrGHAD\
-/gt0kVxJnKZ4GHqBwEc+om/fHRIKN5ZDkEE0BMXwI4wHTRBxGnnniwBSBIBfA/zyGB/HET6F3FVO\
-yMSAO75HeUv850hTGmWVcwOWy3ikgjEH+hiMYTCmiiPADWM86AZc6d78O/Y9dglJjCtK6PPcMJeB\
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-si7rsi7r8qcs/w8AInVFAFAAAA==\
+RUN echo \\
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+LgyDM2eUPZUhHiPhq3nPpyMmqnJ1isXssiHZtBRNovV9+cYSSiihhBJKKKGEEkoooYQSSiihhBJK\
+KKGEEkoooYQSSiihhBJKKKGEEkoooYQSSiihhH9H+D9i0BbqAHgAAA==\
 | base64 -d | tar xzC /tmp
 
 # Import patch files for ruby and gems
@@ -105,8 +106,10 @@
 # install rubies and fix permissions on
 RUN bash -c " \
     export CFLAGS='-s -O3 -fno-fast-math -fPIC' && \
-    for v in 2.3.0 ; do \
-        rvm install \$v --patch \$(echo ~/patches/ruby-\$v/* | tr ' ' ','); \
+    echo 'about to install patches for ruby 2.4.0 from:' && \
+    ls -r ~/patches && \
+    for v in 2.4.0 ; do \
+	rvm install \$v --patch \$(echo ~/patches/ruby-\$v/* | tr ' ' ','); \
     done && \
     rvm cleanup all && \
     find /usr/local/rvm -type d -print0 | sudo xargs -0 chmod g+sw "
@@ -116,20 +119,26 @@
 RUN echo "gem: --no-ri --no-rdoc" >> ~/.gemrc && \
     bash -c " \
         rvm all do gem install bundler rake-compiler hoe mini_portile rubygems-tasks && \
-        rvm 2.3.0 do gem install mini_portile2 && \
+        rvm 2.4.0 do gem install mini_portile2 && \
         find /usr/local/rvm -type d -print0 | sudo xargs -0 chmod g+sw "
 
+RUN bash -c "gem env"
+RUN bash -c "gem list rake-compiler"
+
 # Install rake-compiler's cross rubies in global dir instead of /root
 RUN sudo mkdir -p /usr/local/rake-compiler && \
     sudo chown rvm.rvm /usr/local/rake-compiler && \
     ln -s /usr/local/rake-compiler ~/.rake-compiler
 
 # Patch rake-compiler to avoid build of ruby extensions
-RUN cd /usr/local/rvm/gems/ruby-2.3.0/gems/rake-compiler-0.9.5 && git apply /home/rvm/patches/rake-compiler-0.9.5/*.diff ; \
+RUN cd /usr/local/rvm/gems/ruby-2.4.0/gems/rake-compiler-0.9.5 && git apply /home/rvm/patches/rake-compiler-0.9.5/*.diff ; \
     true
 
-RUN bash -c "rvm use 2.3.0 --default && \
+RUN bash -c "rvm use 2.4.0 --default && \
     export MAKE=\"make -j`nproc`\" CFLAGS='-s -O1 -fno-omit-frame-pointer -fno-fast-math' && \
+    rake-compiler cross-ruby VERSION=2.4.0 HOST=i686-w64-mingw32 && \
+    rake-compiler cross-ruby VERSION=2.4.0 HOST=x86_64-w64-mingw32 && \
+    rake-compiler cross-ruby VERSION=2.4.0 HOST=x86_64-linux-gnu && \
     rake-compiler cross-ruby VERSION=2.3.0 HOST=i686-w64-mingw32 && \
     rake-compiler cross-ruby VERSION=2.3.0 HOST=x86_64-w64-mingw32 && \
     rake-compiler cross-ruby VERSION=2.3.0 HOST=x86_64-linux-gnu && \
@@ -145,8 +154,9 @@
     rm -rf ~/.rake-compiler/tmp/builds ~/.rake-compiler/sources && \
     find /usr/local/rvm -type d -print0 | sudo xargs -0 chmod g+sw "
 
-RUN bash -c "rvm use 2.3.0 --default && \
+RUN bash -c "rvm use 2.4.0 --default && \
     export MAKE=\"make -j`nproc`\" CFLAGS='-m32 -s -O1 -fno-omit-frame-pointer -fno-fast-math' LDFLAGS='-m32' && \
+    rake-compiler cross-ruby VERSION=2.4.0 HOST=i686-linux-gnu && \
     rake-compiler cross-ruby VERSION=2.3.0 HOST=i686-linux-gnu && \
     rake-compiler cross-ruby VERSION=2.2.2 HOST=i686-linux-gnu && \
     rake-compiler cross-ruby VERSION=2.1.5 HOST=i686-linux-gnu && \
@@ -155,7 +165,7 @@
     find /usr/local/rvm -type d -print0 | sudo xargs -0 chmod g+sw "
 
 RUN bash -c " \
-    rvm alias create 2.3 2.3.0 "
+    rvm alias create 2.4 2.4.0 "
 
 USER root
 
@@ -167,6 +177,7 @@
 
 # Install wrappers for strip commands as a workaround for "Protocol error" in boot2docker.
 RUN cp /tmp/build/strip_wrapper /root/
+RUN sudo chmod +rx /root/strip_wrapper
 RUN mv /opt/mingw/mingw32/bin/i686-w64-mingw32-strip /opt/mingw/mingw32/bin/i686-w64-mingw32-strip.bin && \
     mv /opt/mingw/mingw64/bin/x86_64-w64-mingw32-strip /opt/mingw/mingw64/bin/x86_64-w64-mingw32-strip.bin && \
     mv /usr/bin/i686-w64-mingw32-strip /usr/bin/i686-w64-mingw32-strip.bin && \
@@ -196,6 +207,10 @@
 # Install sudoers configuration
 RUN cp /tmp/build/sudoers /etc/sudoers.d/rake-compiler-dock
 
-ENV RUBY_CC_VERSION 2.3.0:2.2.2:2.1.5:2.0.0
+# Fixup Ruby 2.4 'static' compilation issue.
+RUN echo '!<arch>' > /usr/local/rake-compiler/ruby/x86_64-linux-gnu/ruby-2.4.0/lib/libruby.a
+RUN echo '!<arch>' > /usr/local/rake-compiler/ruby/i686-linux-gnu/ruby-2.4.0/lib/libruby.a
+
+ENV RUBY_CC_VERSION 2.4.0:2.3.0:2.2.2:2.1.5:2.0.0
 
 CMD bash
diff --git a/third_party/rake-compiler-dock/build/patches/ruby-2.4.0/no_sendfile.patch b/third_party/rake-compiler-dock/build/patches/ruby-2.4.0/no_sendfile.patch
new file mode 100644
index 0000000..915fc7b
--- /dev/null
+++ b/third_party/rake-compiler-dock/build/patches/ruby-2.4.0/no_sendfile.patch
@@ -0,0 +1,12 @@
+diff --git a/configure b/configure
+index ebe3d8c..a336b73 100755
+--- a/configure
++++ b/configure
+@@ -18943,7 +18943,6 @@ do :
+   ac_fn_c_check_func "$LINENO" "sendfile" "ac_cv_func_sendfile"
+ if test "x$ac_cv_func_sendfile" = xyes; then :
+   cat >>confdefs.h <<_ACEOF
+-#define HAVE_SENDFILE 1
+ _ACEOF
+ 
+ fi
diff --git a/tools/distrib/build_ruby_environment_macos.sh b/tools/distrib/build_ruby_environment_macos.sh
index 64fad7c..0ae589c 100644
--- a/tools/distrib/build_ruby_environment_macos.sh
+++ b/tools/distrib/build_ruby_environment_macos.sh
@@ -34,7 +34,7 @@
 
 CROSS_RUBY=`mktemp tmpfile.XXXXXXXX`
 
-curl https://raw.githubusercontent.com/rake-compiler/rake-compiler/v0.9.5/tasks/bin/cross-ruby.rake > $CROSS_RUBY
+curl https://raw.githubusercontent.com/rake-compiler/rake-compiler/v1.0.3/tasks/bin/cross-ruby.rake > $CROSS_RUBY
 
 patch $CROSS_RUBY << EOF
 --- cross-ruby.rake	2016-02-05 16:26:53.000000000 -0800
@@ -53,7 +53,8 @@
 
 MAKE="make -j8"
 
-for v in 2.3.0 2.2.2 2.1.5 2.0.0-p645 ; do
+for v in 2.4.0 2.3.0 2.2.2 2.1.5 2.0.0-p645 ; do
+  ccache -c
   rake -f $CROSS_RUBY cross-ruby VERSION=$v HOST=x86_64-darwin11
 done
 
diff --git a/tools/run_tests/artifacts/build_artifact_ruby.sh b/tools/run_tests/artifacts/build_artifact_ruby.sh
index 019efb0..ca461ba 100755
--- a/tools/run_tests/artifacts/build_artifact_ruby.sh
+++ b/tools/run_tests/artifacts/build_artifact_ruby.sh
@@ -52,7 +52,9 @@
 set +ex
 rvm use default
 gem install bundler --update
-bundle install
+
+tools/run_tests/helper_scripts/bundle_install_wrapper.sh
+
 set -ex
 
 rake gem:native
diff --git a/tools/run_tests/helper_scripts/bundle_install_wrapper.sh b/tools/run_tests/helper_scripts/bundle_install_wrapper.sh
new file mode 100755
index 0000000..d56afad
--- /dev/null
+++ b/tools/run_tests/helper_scripts/bundle_install_wrapper.sh
@@ -0,0 +1,46 @@
+#!/bin/bash
+
+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+set -ex
+
+# change to grpc repo root
+cd $(dirname $0)/../../..
+
+SYSTEM=`uname | cut -f 1 -d_`
+
+if [ "$SYSTEM" == "Darwin" ] ; then
+  # Workaround for crash during bundle install
+  # See suggestion in https://github.com/bundler/bundler/issues/3692
+  BUNDLE_SPECIFIC_PLATFORM=true bundle install
+else
+  bundle install
+fi
+
diff --git a/tools/run_tests/helper_scripts/pre_build_ruby.sh b/tools/run_tests/helper_scripts/pre_build_ruby.sh
index 56b58df..83647b5 100755
--- a/tools/run_tests/helper_scripts/pre_build_ruby.sh
+++ b/tools/run_tests/helper_scripts/pre_build_ruby.sh
@@ -36,4 +36,4 @@
 # change to grpc repo root
 cd $(dirname $0)/../../..
 
-bundle install
+tools/run_tests/helper_scripts/bundle_install_wrapper.sh
diff --git a/tools/run_tests/helper_scripts/run_node_electron.sh b/tools/run_tests/helper_scripts/run_node_electron.sh
index 1999ffb..3ce57e0 100755
--- a/tools/run_tests/helper_scripts/run_node_electron.sh
+++ b/tools/run_tests/helper_scripts/run_node_electron.sh
@@ -34,7 +34,7 @@
 set -ex
 
 # change to grpc repo root
-cd $(dirname $0)/../..
+cd $(dirname $0)/../../..
 
 test_directory='src/node/test'
 timeout=8000