Add calls to grpc_recycle_unused_port to two of the tests which call
grpc_pick_unused_port a lot.
diff --git a/test/core/end2end/dualstack_socket_test.c b/test/core/end2end/dualstack_socket_test.c
index 81f76ea..202fb3b 100644
--- a/test/core/end2end/dualstack_socket_test.c
+++ b/test/core/end2end/dualstack_socket_test.c
@@ -88,9 +88,11 @@
   int was_cancelled = 2;
   grpc_call_details call_details;
   char *peer;
+  int picked_port = 0;
 
   if (port == 0) {
     port = grpc_pick_unused_port_or_die();
+    picked_port = 1;
   }
 
   gpr_join_host_port(&server_hostport, server_host, port);
@@ -263,6 +265,9 @@
 
   grpc_call_details_destroy(&call_details);
   gpr_free(details);
+  if (picked_port) {
+    grpc_recycle_unused_port(port);
+  }
 }
 
 int external_dns_works(const char *host) {
diff --git a/test/cpp/end2end/async_end2end_test.cc b/test/cpp/end2end/async_end2end_test.cc
index e0649bd..45f5eb1 100644
--- a/test/cpp/end2end/async_end2end_test.cc
+++ b/test/cpp/end2end/async_end2end_test.cc
@@ -245,8 +245,8 @@
   void SetUp() GRPC_OVERRIDE {
     poll_overrider_.reset(new PollingOverrider(!GetParam().disable_blocking));
 
-    int port = grpc_pick_unused_port_or_die();
-    server_address_ << "localhost:" << port;
+    port_ = grpc_pick_unused_port_or_die();
+    server_address_ << "localhost:" << port_;
 
     // Setup server
     ServerBuilder builder;
@@ -274,6 +274,7 @@
       ;
     poll_overrider_.reset();
     gpr_tls_set(&g_is_async_end2end_test, 0);
+    grpc_recycle_unused_port(port_);
   }
 
   void ResetStub() {
@@ -325,6 +326,7 @@
   std::unique_ptr<Server> server_;
   grpc::testing::EchoTestService::AsyncService service_;
   std::ostringstream server_address_;
+  int port_;
 
   std::unique_ptr<PollingOverrider> poll_overrider_;
 };