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Move CheckPointBuffers to PreCheckPointGuts to save FSM/VM pages on normal shutdown #615

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Merged
knizhnik merged 2 commits into from
Apr 7, 2025
Merged

Move CheckPointBuffers to PreCheckPointGuts to save FSM/VM pages on normal shutdown #615

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3d6c8cf
Move CheckPointBuffers to PreCheckPointGuts to save FSM/VM pages on n…
knizhnik Apr 4, 2025
a039190
Add comment explaning why CheckPointBuffers has to be called in PreCh…
knizhnik Apr 4, 2025
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15 changes: 13 additions & 2 deletions src/backend/access/transam/xlog.c
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Original file line number Diff line number Diff line change
Expand Up @@ -9955,13 +9955,17 @@ CheckPointReplicationState(void)
/*
* NEON: we use logical records to persist information of about slots, origins, relation map...
* If it is done inside shutdown checkpoint, then Postgres panics: "concurrent write-ahead log activity while database system is shutting down"
* So it before checkpoint REDO position is determined.
* So do it before checkpoint REDO position is determined.
* The same is true for CheckPointBuffers which wallog dirty FSM/VM pages.
*/
static void
PreCheckPointGuts(int flags)
{
if (flags & CHECKPOINT_IS_SHUTDOWN)
{
CheckPointReplicationState();
CheckPointBuffers(flags);
}
}

/*
Expand All @@ -9984,7 +9988,14 @@ CheckPointGuts(XLogRecPtr checkPointRedo, int flags)
CheckPointSUBTRANS();
CheckPointMultiXact();
CheckPointPredicate();
CheckPointBuffers(flags);
/*
* NEON: Checkpoint buffer will write dirty pages to the disk and Neon SMGR
* wallog FSM/VM pages to persist them at page server.
* Writing to the WAL during shutdown checkpoint cause Postgres panic.
* So do it before in PreCheckPointGuts.
*/
if (!(flags & CHECKPOINT_IS_SHUTDOWN))
CheckPointBuffers(flags);

/* Perform all queued up fsyncs */
TRACE_POSTGRESQL_BUFFER_CHECKPOINT_SYNC_START();
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