Hello,
On 2024-Apr-03, Alexander Lakhin wrote:
> I've managed to trigger an assert added by 53c2a97a9.
> Please try the following script against a server compiled with
> -DTEST_SUMMARIZE_SERIAL (initially I observed this failure without the
> define, it just simplifies reproducing...):
Ah yes, absolutely, we're missing to trade the correct SLRU bank lock
there. This rewrite of that small piece should fix it. Thanks for
reporting this.
--
Álvaro Herrera PostgreSQL Developer — https://www.EnterpriseDB.com/
"Pido que me den el Nobel por razones humanitarias" (Nicanor Parra)
>From 44c39cf4bf258fb0b65aa1acc5f84e5d7f729eb1 Mon Sep 17 00:00:00 2001
From: Alvaro Herrera <alvhe...@alvh.no-ip.org>
Date: Wed, 3 Apr 2024 16:00:24 +0200
Subject: [PATCH] Fix zeroing of pg_serial page without SLRU bank lock
---
src/backend/storage/lmgr/predicate.c | 19 ++++++++++++-------
1 file changed, 12 insertions(+), 7 deletions(-)
diff --git a/src/backend/storage/lmgr/predicate.c b/src/backend/storage/lmgr/predicate.c
index 3f378c0099..d5bbfbd4c6 100644
--- a/src/backend/storage/lmgr/predicate.c
+++ b/src/backend/storage/lmgr/predicate.c
@@ -137,7 +137,7 @@
* SerialControlLock
* - Protects SerialControlData members
*
- * SerialSLRULock
+ * SLRU per-bank locks
* - Protects SerialSlruCtl
*
* Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
@@ -908,20 +908,25 @@ SerialAdd(TransactionId xid, SerCommitSeqNo minConflictCommitSeqNo)
if (isNewPage)
serialControl->headPage = targetPage;
- LWLockAcquire(lock, LW_EXCLUSIVE);
-
if (isNewPage)
{
- /* Initialize intervening pages. */
- while (firstZeroPage != targetPage)
+ /* Initialize intervening pages; might involve trading locks */
+ for (;;)
{
- (void) SimpleLruZeroPage(SerialSlruCtl, firstZeroPage);
+ lock = SimpleLruGetBankLock(SerialSlruCtl, firstZeroPage);
+ LWLockAcquire(lock, LW_EXCLUSIVE);
+ slotno = SimpleLruZeroPage(SerialSlruCtl, firstZeroPage);
+ if (firstZeroPage == targetPage)
+ break;
firstZeroPage = SerialNextPage(firstZeroPage);
+ LWLockRelease(lock);
}
- slotno = SimpleLruZeroPage(SerialSlruCtl, targetPage);
}
else
+ {
+ LWLockAcquire(lock, LW_EXCLUSIVE);
slotno = SimpleLruReadPage(SerialSlruCtl, targetPage, true, xid);
+ }
SerialValue(slotno, xid) = minConflictCommitSeqNo;
SerialSlruCtl->shared->page_dirty[slotno] = true;
--
2.39.2
