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| author | Alexander Korotkov <akorotkov@postgresql.org> | 2025-08-07 14:29:02 +0300 |
|---|---|---|
| committer | Alexander Korotkov <akorotkov@postgresql.org> | 2025-08-07 14:31:24 +0300 |
| commit | 73f897ba5836c1341bec460c618ac76264d986c8 (patch) | |
| tree | cd759cf1c60f8e7a9c6ca32fb9948d34a25c02cf | |
| parent | 098c27dee4c15222daeb9c15a3db8ec18d24a26f (diff) | |
Fix checkpointer shared memory allocation
Use Min(NBuffers, MAX_CHECKPOINT_REQUESTS) instead of NBuffers in
CheckpointerShmemSize() to match the actual array size limit set in
CheckpointerShmemInit(). This prevents wasting shared memory when
NBuffers > MAX_CHECKPOINT_REQUESTS. Also, fix the comment.
Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/1439188.1754506714%40sss.pgh.pa.us
Author: Xuneng Zhou <xunengzhou@gmail.com>
Co-authored-by: Alexander Korotkov <aekorotkov@gmail.com>
| -rw-r--r-- | src/backend/postmaster/checkpointer.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/src/backend/postmaster/checkpointer.c b/src/backend/postmaster/checkpointer.c index 27f3ab3c086..958fdf571ba 100644 --- a/src/backend/postmaster/checkpointer.c +++ b/src/backend/postmaster/checkpointer.c @@ -874,11 +874,14 @@ CheckpointerShmemSize(void) Size size; /* - * Currently, the size of the requests[] array is arbitrarily set equal to - * NBuffers. This may prove too large or small ... + * The size of the requests[] array is arbitrarily set equal to NBuffers. + * But there is a cap of MAX_CHECKPOINT_REQUESTS to prevent accumulating + * too many checkpoint requests in the ring buffer. */ size = offsetof(CheckpointerShmemStruct, requests); - size = add_size(size, mul_size(NBuffers, sizeof(CheckpointerRequest))); + size = add_size(size, mul_size(Min(NBuffers, + MAX_CHECKPOINT_REQUESTS), + sizeof(CheckpointerRequest))); return size; } |