v1-0001-Fix-checkpointer-shared-memory-allocation.patch

From 3d9cb6b21a6e44e892e41cba35dd1caff3f437d1 Mon Sep 17 00:00:00 2001
From: alterego665 <824662526@qq.com>
Date: Thu, 7 Aug 2025 15:03:10 +0800
Subject: [PATCH v1] Fix checkpointer shared memory allocation

Use 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.
---
 src/backend/postmaster/checkpointer.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/src/backend/postmaster/checkpointer.c b/src/backend/postmaster/checkpointer.c
index 8490148a47d..8d52b24ed05 100644
--- a/src/backend/postmaster/checkpointer.c
+++ b/src/backend/postmaster/checkpointer.c
@@ -953,11 +953,10 @@ 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 capped at MAX_CHECKPOINT_REQUESTS.
 	 */
 	size = offsetof(CheckpointerShmemStruct, requests);
-	size = add_size(size, mul_size(NBuffers, sizeof(CheckpointerRequest)));
+	size = add_size(size, mul_size(MAX_CHECKPOINT_REQUESTS, sizeof(CheckpointerRequest)));
 
 	return size;
 }
-- 
2.49.0