fix_worker_startup_failures_v1.patch

diff --git a/src/backend/access/transam/parallel.c b/src/backend/access/transam/parallel.c
index 13c8ba3..189d790 100644
--- a/src/backend/access/transam/parallel.c
+++ b/src/backend/access/transam/parallel.c
@@ -546,7 +546,16 @@ WaitForParallelWorkersToFinish(ParallelContext *pcxt)
 
 		for (i = 0; i < pcxt->nworkers_launched; ++i)
 		{
-			if (pcxt->worker[i].error_mqh != NULL)
+			pid_t		pid;
+
+			/*
+			 * Check for unexpected worker death.  This will ensure that if
+			 * the postmaster failed to start the worker, then we don't wait
+			 * for it indefinitely.
+			 */
+			if (pcxt->worker[i].error_mqh != NULL &&
+				pcxt->worker[i].bgwhandle != NULL &&
+				GetBackgroundWorkerPid(pcxt->worker[i].bgwhandle, &pid) != BGWH_STOPPED)
 			{
 				anyone_alive = true;
 				break;
diff --git a/src/backend/postmaster/bgworker.c b/src/backend/postmaster/bgworker.c
index 28af6f0..83a390c 100644
--- a/src/backend/postmaster/bgworker.c
+++ b/src/backend/postmaster/bgworker.c
@@ -1031,7 +1031,8 @@ RegisterDynamicBackgroundWorker(BackgroundWorker *worker,
  * BGWH_STARTED and *pidp will get the PID of the worker process.
  * Otherwise, the return value will be BGWH_NOT_YET_STARTED if the worker
  * hasn't been started yet, and BGWH_STOPPED if the worker was previously
- * running but is no longer.
+ * running but is no longer or postmaster has failed to start the worker due
+ * to fork failure or such conditions.
  *
  * In the latter case, the worker may be stopped temporarily (if it is
  * configured for automatic restart and exited non-zero) or gone for
@@ -1061,7 +1062,8 @@ GetBackgroundWorkerPid(BackgroundWorkerHandle *handle, pid_t *pidp)
 	 * won't be garbage, but it might be out of date by the time the caller
 	 * examines it (but that's unavoidable anyway).
 	 */
-	if (handle->generation != slot->generation)
+	if (handle->generation != slot->generation ||
+		!slot->in_use)
 		pid = 0;
 	else
 		pid = slot->pid;
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index e4f8f59..7119359 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -5854,7 +5854,15 @@ maybe_start_bgworkers(void)
 		{
 			if (rw->rw_worker.bgw_restart_time == BGW_NEVER_RESTART)
 			{
+				int			notify_pid;
+
+				notify_pid = rw->rw_worker.bgw_notify_pid;
+
 				ForgetBackgroundWorker(&iter);
+
+				/* Report worker is gone now. */
+				if (notify_pid != 0)
+					kill(notify_pid, SIGUSR1);
 				continue;
 			}