From 0198d7fb73f1d19ba6ae6a004204a1737affe742 Mon Sep 17 00:00:00 2001 From: Alexander Korotkov Date: Thu, 26 Jun 2025 00:32:38 +0300 Subject: [PATCH v1] Fix CheckPointReplicationSlots() with max_replication_slots == 0 ca307d5cec90 made CheckPointReplicationSlots() unconditionally call ReplicationSlotsComputeRequiredLSN(). It causes an assertion trap when max_replication_slots equals 0. This commit makes CheckPointReplicationSlots() call ReplicationSlotsComputeRequiredLSN() only when at least one slot gets its last_saved_restart_lsn updated. That avoids an assert trap and also saves some cycles when no one slot has last_saved_restart_lsn updated. Based on ideas from Dilip Kumar and Hayato Kuroda . Reported-by: Zhijie Hou Discussion: https://postgr.es/m/OS0PR01MB5716BB506AF934376FF3A8BB947BA%40OS0PR01MB5716.jpnprd01.prod.outlook.com --- src/backend/replication/slot.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c index c11e588d632..30177388508 100644 --- a/src/backend/replication/slot.c +++ b/src/backend/replication/slot.c @@ -2079,6 +2079,7 @@ void CheckPointReplicationSlots(bool is_shutdown) { int i; + bool last_saved_restart_lsn_updated = false; elog(DEBUG1, "performing replication slot checkpoint"); @@ -2123,15 +2124,23 @@ CheckPointReplicationSlots(bool is_shutdown) SpinLockRelease(&s->mutex); } + /* + * Track if we're going to update slot's last_saved_restart_lsn. + * We need this to know if we need to recompute the required LSN. + */ + if (s->last_saved_restart_lsn != s->data.restart_lsn) + last_saved_restart_lsn_updated = true; + SaveSlotToPath(s, path, LOG); } LWLockRelease(ReplicationSlotAllocationLock); /* - * Recompute the required LSN as SaveSlotToPath() updated - * last_saved_restart_lsn for slots. + * Recompute the required LSN if SaveSlotToPath() updated + * last_saved_restart_lsn for any slot. */ - ReplicationSlotsComputeRequiredLSN(); + if (last_saved_restart_lsn_updated) + ReplicationSlotsComputeRequiredLSN(); } /* -- 2.39.5 (Apple Git-154)