Merge pull request #13776 from ncteisen/executor-tsan

Fix shutdown executor tsan bug
diff --git a/src/core/lib/iomgr/executor.cc b/src/core/lib/iomgr/executor.cc
index b7288d5..67a0412 100644
--- a/src/core/lib/iomgr/executor.cc
+++ b/src/core/lib/iomgr/executor.cc
@@ -242,7 +242,7 @@
         }
         continue;
       }
-      if (grpc_closure_list_empty(ts->elems)) {
+      if (grpc_closure_list_empty(ts->elems) && !ts->shutdown) {
         GRPC_STATS_INC_EXECUTOR_WAKEUP_INITIATED();
         gpr_cv_signal(&ts->cv);
       }