Allocate Backend structs in PostmasterContext.

hlinnaka · hlinnaka · commit 0bbafb534275 · 2023-10-09T11:29:39.000+03:00
The child processes don't need them. By allocating them in PostmasterContext, the memory gets free'd and is made available for other stuff in the child processes. Reviewed-by: Thomas Munro Discussion: https://www.postgresql.org/message-id/4f95c1fc-ad3c-7974-3a8c-6faa3931804c@iki.fi
diff --git a/src/backend/postmaster/bgworker.c b/src/backend/postmaster/bgworker.c
@@ -33,6 +33,7 @@
 #include "storage/shmem.h"
 #include "tcop/tcopprot.h"
 #include "utils/ascii.h"
+#include "utils/memutils.h"
 #include "utils/ps_status.h"
 #include "utils/timeout.h"
 
@@ -347,7 +348,9 @@ BackgroundWorkerStateChange(bool allow_new_workers)
 		/*
 		 * Copy the registration data into the registered workers list.
 		 */
-		rw = malloc(sizeof(RegisteredBgWorker));
+		rw = MemoryContextAllocExtended(PostmasterContext,
+										sizeof(RegisteredBgWorker),
+										MCXT_ALLOC_NO_OOM);
 		if (rw == NULL)
 		{
 			ereport(LOG,
@@ -455,7 +458,7 @@ ForgetBackgroundWorker(slist_mutable_iter *cur)
 							 rw->rw_worker.bgw_name)));
 
 	slist_delete_current(cur);
-	free(rw);
+	pfree(rw);
 }
 
 /*
@@ -951,7 +954,9 @@ RegisterBackgroundWorker(BackgroundWorker *worker)
 	/*
 	 * Copy the registration data into the registered workers list.
 	 */
-	rw = malloc(sizeof(RegisteredBgWorker));
+	rw = MemoryContextAllocExtended(PostmasterContext,
+									sizeof(RegisteredBgWorker),
+									MCXT_ALLOC_NO_OOM);
 	if (rw == NULL)
 	{
 		ereport(LOG,
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
@@ -3321,7 +3321,7 @@ CleanupBackgroundWorker(int pid,
 		 */
 		if (rw->rw_backend->bgworker_notify)
 			BackgroundWorkerStopNotifications(rw->rw_pid);
-		free(rw->rw_backend);
+		pfree(rw->rw_backend);
 		rw->rw_backend = NULL;
 		rw->rw_pid = 0;
 		rw->rw_child_slot = 0;
@@ -3414,7 +3414,7 @@ CleanupBackend(int pid,
 				BackgroundWorkerStopNotifications(bp->pid);
 			}
 			dlist_delete(iter.cur);
-			free(bp);
+			pfree(bp);
 			break;
 		}
 	}
@@ -3470,7 +3470,7 @@ HandleChildCrash(int pid, int exitstatus, const char *procname)
 #ifdef EXEC_BACKEND
 			ShmemBackendArrayRemove(rw->rw_backend);
 #endif
-			free(rw->rw_backend);
+			pfree(rw->rw_backend);
 			rw->rw_backend = NULL;
 			rw->rw_pid = 0;
 			rw->rw_child_slot = 0;
@@ -3507,7 +3507,7 @@ HandleChildCrash(int pid, int exitstatus, const char *procname)
 #endif
 			}
 			dlist_delete(iter.cur);
-			free(bp);
+			pfree(bp);
 			/* Keep looping so we can signal remaining backends */
 		}
 		else
@@ -4083,7 +4083,7 @@ BackendStartup(Port *port)
 	 * Create backend data structure.  Better before the fork() so we can
 	 * handle failure cleanly.
 	 */
-	bn = (Backend *) malloc(sizeof(Backend));
+	bn = (Backend *) palloc_extended(sizeof(Backend), MCXT_ALLOC_NO_OOM);
 	if (!bn)
 	{
 		ereport(LOG,
@@ -4099,7 +4099,7 @@ BackendStartup(Port *port)
 	 */
 	if (!RandomCancelKey(&MyCancelKey))
 	{
-		free(bn);
+		pfree(bn);
 		ereport(LOG,
 				(errcode(ERRCODE_INTERNAL_ERROR),
 				 errmsg("could not generate random cancel key")));
@@ -4129,8 +4129,6 @@ BackendStartup(Port *port)
 	pid = fork_process();
 	if (pid == 0)				/* child */
 	{
-		free(bn);
-
 		/* Detangle from postmaster */
 		InitPostmasterChild();
 
@@ -4161,7 +4159,7 @@ BackendStartup(Port *port)
 
 		if (!bn->dead_end)
 			(void) ReleasePostmasterChildSlot(bn->child_slot);
-		free(bn);
+		pfree(bn);
 		errno = save_errno;
 		ereport(LOG,
 				(errmsg("could not fork new process for connection: %m")));
@@ -5424,7 +5422,7 @@ StartAutovacuumWorker(void)
 			return;
 		}
 
-		bn = (Backend *) malloc(sizeof(Backend));
+		bn = (Backend *) palloc_extended(sizeof(Backend), MCXT_ALLOC_NO_OOM);
 		if (bn)
 		{
 			bn->cancel_key = MyCancelKey;
@@ -5451,7 +5449,7 @@ StartAutovacuumWorker(void)
 			 * logged by StartAutoVacWorker
 			 */
 			(void) ReleasePostmasterChildSlot(bn->child_slot);
-			free(bn);
+			pfree(bn);
 		}
 		else
 			ereport(LOG,
@@ -5696,7 +5694,7 @@ do_start_bgworker(RegisteredBgWorker *rw)
 			/* undo what assign_backendlist_entry did */
 			ReleasePostmasterChildSlot(rw->rw_child_slot);
 			rw->rw_child_slot = 0;
-			free(rw->rw_backend);
+			pfree(rw->rw_backend);
 			rw->rw_backend = NULL;
 			/* mark entry as crashed, so we'll try again later */
 			rw->rw_crashed_at = GetCurrentTimestamp();
@@ -5822,7 +5820,7 @@ assign_backendlist_entry(RegisteredBgWorker *rw)
 		return false;
 	}
 
-	bn = malloc(sizeof(Backend));
+	bn = palloc_extended(sizeof(Backend), MCXT_ALLOC_NO_OOM);
 	if (bn == NULL)
 	{
 		ereport(LOG,
