postgres.git / summary / log / commit / refs
commit f0cdc2afd15e51f580e53ebd269bd66ec0aaaa79
Author: Alexander Korotkov <akorotkov@postgresql.org>
Date: Sun Jul 27 12:10:01 2025 +0000
First released in: 13.22, 14.19, 15.14, 16.10, 17.6, 18.0
Limit checkpointer requests queue size
If the number of sync requests is big enough, the palloc() call in
AbsorbSyncRequests() will attempt to allocate more than 1 GB of memory,
resulting in failure. This can lead to an infinite loop in the checkpointer
process, as it repeatedly fails to absorb the pending requests.
This commit limits the checkpointer requests queue size to 10M items. In
addition to preventing the palloc() failure, this change helps to avoid long
queue processing time.
Also, this commit is for backpathing only. The master branch receives
a more invasive yet comprehensive fix for this problem.
Discussion: https://postgr.es/m/db4534f83a22a29ab5ee2566ad86ca92%40postgrespro.ru
Backpatch-through: 13
src/backend/postmaster/checkpointer.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/src/backend/postmaster/checkpointer.c b/src/backend/postmaster/checkpointer.c
index f482f6423d1..e93bf38a4f6 100644
--- a/src/backend/postmaster/checkpointer.c
+++ b/src/backend/postmaster/checkpointer.c
@@ -138,6 +138,9 @@ static CheckpointerShmemStruct *CheckpointerShmem;
/* interval for calling AbsorbSyncRequests in CheckpointWriteDelay */
#define WRITES_PER_ABSORB 1000
+/* Max number of requests the checkpointer request queue can hold */
+#define MAX_CHECKPOINT_REQUESTS 10000000
+
/*
* GUC parameters
*/
@@ -903,7 +906,7 @@ CheckpointerShmemInit(void)
*/
MemSet(CheckpointerShmem, 0, size);
SpinLockInit(&CheckpointerShmem->ckpt_lck);
- CheckpointerShmem->max_requests = NBuffers;
+ CheckpointerShmem->max_requests = Min(NBuffers, MAX_CHECKPOINT_REQUESTS);
ConditionVariableInit(&CheckpointerShmem->start_cv);
ConditionVariableInit(&CheckpointerShmem->done_cv);
}
[parent: e4d585455509]