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Fix WAL flush LSN used by logical walsender during shutdown

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Commit 6eedb2a5fd made the logical walsender call
XLogFlush(GetXLogInsertRecPtr()) to ensure that all pending WAL is flushed,
fixing a publisher shutdown hang. However, if the last WAL record ends at
a page boundary, GetXLogInsertRecPtr() can return an LSN pointing past
the page header, which can cause XLogFlush() to report an error.

A similar issue previously existed in the GiST code. Commit b1f14c9672
introduced GetXLogInsertEndRecPtr(), which returns a safe WAL insertion end
location (returning the start of the page when the last record ends at a page
boundary), and updated the GiST code to use it with XLogFlush().

This commit fixes the issue by making the logical walsender use
XLogFlush(GetXLogInsertEndRecPtr()) when flushing pending WAL during shutdown.

Backpatch to all supported versions.

Reported-by: Andres Freund <andres@anarazel.de>
Author: Anthonin Bonnefoy <anthonin.bonnefoy@datadoghq.com>
Reviewed-by: Fujii Masao <masao.fujii@gmail.com>
Discussion: https://postgr.es/m/vzguaguldbcyfbyuq76qj7hx5qdr5kmh67gqkncyb2yhsygrdt@dfhcpteqifux
Backpatch-through: 14
This commit is contained in:
Fujii Masao 2026-03-17 08:10:20 +09:00
parent 34baa313e3
commit fa9f2e3175
1 changed files with 7 additions and 1 deletions
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8
src/backend/replication/walsender.c
View file

@ -1602,9 +1602,15 @@ WalSndWaitForWal(XLogRecPtr loc)
* If we're shutting down, trigger pending WAL to be written out,
* otherwise we'd possibly end up waiting for WAL that never gets
* written, because walwriter has shut down already.
*
* Note that GetXLogInsertEndRecPtr() is used to obtain the WAL flush
* request location instead of GetXLogInsertRecPtr(). Because if the
* last WAL record ends at a page boundary, GetXLogInsertRecPtr() can
* return an LSN pointing past the page header, which may cause
* XLogFlush() to report an error.
*/
if (got_STOPPING && !RecoveryInProgress())
XLogFlush(GetXLogInsertRecPtr());
XLogFlush(GetXLogInsertEndRecPtr());
/* Update our idea of the currently flushed position. */
if (!RecoveryInProgress())