4 files changed, 32 insertions, 8 deletions
diff --git a/src/core/lib/iomgr/exec_ctx.h b/src/core/lib/iomgr/exec_ctx.h
index f3528d527a..e90eb54cd3 100644
--- a/src/core/lib/iomgr/exec_ctx.h
+++ b/src/core/lib/iomgr/exec_ctx.h
@@ -116,12 +116,7 @@ class ExecCtx {
   ExecCtx(const ExecCtx&) = delete;
   ExecCtx& operator=(const ExecCtx&) = delete;
 
-  /** Return starting_cpu. This is only required for stats collection and is
-   *  hence only defined if GRPC_COLLECT_STATS is enabled.
-   */
-#if defined(GRPC_COLLECT_STATS) || !defined(NDEBUG)
   unsigned starting_cpu() const { return starting_cpu_; }
-#endif /* defined(GRPC_COLLECT_STATS) || !defined(NDEBUG) */
 
   struct CombinerData {
     /* currently active combiner: updated only via combiner.c */
@@ -223,9 +218,7 @@ class ExecCtx {
   CombinerData combiner_data_ = {nullptr, nullptr};
   uintptr_t flags_;
 
-#if defined(GRPC_COLLECT_STATS) || !defined(NDEBUG)
   unsigned starting_cpu_ = gpr_cpu_current_cpu();
-#endif /* defined(GRPC_COLLECT_STATS) || !defined(NDEBUG) */
 
   bool now_is_valid_ = false;
   grpc_millis now_ = 0;
diff --git a/src/core/lib/iomgr/port.h b/src/core/lib/iomgr/port.h
index c8046b21dc..bf56a7298d 100644
--- a/src/core/lib/iomgr/port.h
+++ b/src/core/lib/iomgr/port.h
@@ -62,7 +62,8 @@
 #define GRPC_HAVE_UNIX_SOCKET 1
 #ifdef LINUX_VERSION_CODE
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 0, 0)
-#define GRPC_LINUX_ERRQUEUE 1
+/* TODO(yashykt): Re-enable once Fathom changes are commited.
+#define GRPC_LINUX_ERRQUEUE 1 */
 #endif /* LINUX_VERSION_CODE >= KERNEL_VERSION(4, 0, 0) */
 #endif /* LINUX_VERSION_CODE */
 #define GRPC_LINUX_MULTIPOLL_WITH_EPOLL 1
diff --git a/src/core/lib/iomgr/tcp_posix.cc b/src/core/lib/iomgr/tcp_posix.cc
index ac1e919acb..e40bf81c90 100644
--- a/src/core/lib/iomgr/tcp_posix.cc
+++ b/src/core/lib/iomgr/tcp_posix.cc
@@ -204,6 +204,13 @@ static void drop_uncovered(grpc_tcp* tcp) {
   GPR_ASSERT(old_count != 1);
 }
 
+// gRPC API considers a Write operation to be done the moment it clears ‘flow
+// control’ i.e., not necessarily sent on the wire. This means that the
+// application MIGHT not call `grpc_completion_queue_next/pluck` in a timely
+// manner when its `Write()` API is acked.
+//
+// We need to ensure that the fd is 'covered' (i.e being monitored by some
+// polling thread and progress is made) and hence add it to a backup poller here
 static void cover_self(grpc_tcp* tcp) {
   backup_poller* p;
   gpr_atm old_count =
diff --git a/src/core/lib/iomgr/timer_manager.cc b/src/core/lib/iomgr/timer_manager.cc
index 806bae4f21..54f19a9259 100644
--- a/src/core/lib/iomgr/timer_manager.cc
+++ b/src/core/lib/iomgr/timer_manager.cc
@@ -61,6 +61,14 @@ static uint64_t g_timed_waiter_generation;
 
 static void timer_thread(void* completed_thread_ptr);
 
+// For debug of the timer manager crash only.
+// TODO (mxyan): remove after bug is fixed.
+#ifdef GRPC_DEBUG_TIMER_MANAGER
+extern int64_t g_timer_manager_init_count;
+extern int64_t g_timer_manager_shutdown_count;
+extern int64_t g_fork_count;
+#endif  // GRPC_DEBUG_TIMER_MANAGER
+
 static void gc_completed_threads(void) {
   if (g_completed_threads != nullptr) {
     completed_thread* to_gc = g_completed_threads;
@@ -286,6 +294,11 @@ static void start_threads(void) {
 void grpc_timer_manager_init(void) {
   gpr_mu_init(&g_mu);
   gpr_cv_init(&g_cv_wait);
+#ifdef GRPC_DEBUG_TIMER_MANAGER
+  // For debug of the timer manager crash only.
+  // TODO (mxyan): remove after bug is fixed.
+  g_timer_manager_init_count++;
+#endif
   gpr_cv_init(&g_cv_shutdown);
   g_threaded = false;
   g_thread_count = 0;
@@ -321,6 +334,11 @@ static void stop_threads(void) {
 }
 
 void grpc_timer_manager_shutdown(void) {
+#ifdef GRPC_DEBUG_TIMER_MANAGER
+  // For debug of the timer manager crash only.
+  // TODO (mxyan): remove after bug is fixed.
+  g_timer_manager_shutdown_count++;
+#endif
   stop_threads();
 
   gpr_mu_destroy(&g_mu);
@@ -329,6 +347,11 @@ void grpc_timer_manager_shutdown(void) {
 }
 
 void grpc_timer_manager_set_threading(bool threaded) {
+#ifdef GRPC_DEBUG_TIMER_MANAGER
+  // For debug of the timer manager crash only.
+  // TODO (mxyan): remove after bug is fixed.
+  g_fork_count++;
+#endif
   if (threaded) {
     start_threads();
   } else {