Merge pull request #15825 from kpayson64/exec_ctx_check_bugfix

Don't count internal threads against ExecCtx count

src/core/lib/iomgr/exec_ctx.h

@@ -45,6 +45,9 @@ typedef struct grpc_combiner grpc_combiner;
 /* The exec_ctx's thread is (potentially) owned by a call or channel: care
    should be given to not delete said call/channel from this exec_ctx */
 #define GRPC_EXEC_CTX_FLAG_THREAD_RESOURCE_LOOP 2
+/* This exec ctx was initialized by an internal thread, and should not
+   be counted by fork handlers */
+#define GRPC_EXEC_CTX_FLAG_IS_INTERNAL_THREAD 4
 
 extern grpc_closure_scheduler* grpc_schedule_on_exec_ctx;
 
@@ -93,7 +96,9 @@ class ExecCtx {
 
   /** Parameterised Constructor */
   ExecCtx(uintptr_t fl) : flags_(fl) {
-    grpc_core::Fork::IncExecCtxCount();
+    if (!(GRPC_EXEC_CTX_FLAG_IS_INTERNAL_THREAD & flags_)) {
+      grpc_core::Fork::IncExecCtxCount();
+    }
     Set(this);
   }
 
@@ -102,7 +107,9 @@ class ExecCtx {
     flags_ |= GRPC_EXEC_CTX_FLAG_IS_FINISHED;
     Flush();
     Set(last_exec_ctx_);
-    grpc_core::Fork::DecExecCtxCount();
+    if (!(GRPC_EXEC_CTX_FLAG_IS_INTERNAL_THREAD & flags_)) {
+      grpc_core::Fork::DecExecCtxCount();
+    }
   }
 
   /** Disallow copy and assignment operators */

src/core/lib/iomgr/executor.cc

@@ -145,7 +145,7 @@ static void executor_thread(void* arg) {
   thread_state* ts = static_cast<thread_state*>(arg);
   gpr_tls_set(&g_this_thread_state, (intptr_t)ts);
 
-  grpc_core::ExecCtx exec_ctx(0);
+  grpc_core::ExecCtx exec_ctx(GRPC_EXEC_CTX_FLAG_IS_INTERNAL_THREAD);
 
   size_t subtract_depth = 0;
   for (;;) {

src/core/lib/iomgr/timer_manager.cc

@@ -265,7 +265,7 @@ static void timer_thread_cleanup(completed_thread* ct) {
 static void timer_thread(void* completed_thread_ptr) {
   // this threads exec_ctx: we try to run things through to completion here
   // since it's easy to spin up new threads
-  grpc_core::ExecCtx exec_ctx(0);
+  grpc_core::ExecCtx exec_ctx(GRPC_EXEC_CTX_FLAG_IS_INTERNAL_THREAD);
   timer_main_loop();
 
   timer_thread_cleanup(static_cast<completed_thread*>(completed_thread_ptr));