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Advance old-segment horizon properly after slot invalidation

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When some slots are invalidated due to the max_slot_wal_keep_size limit,
the old segment horizon should move forward to stay within the limit.
However, in commit c655077639 we forgot to call KeepLogSeg again to
recompute the horizon after invalidating replication slots.  In cases
where other slots remained, the limits would be recomputed eventually
for other reasons, but if all slots were invalidated, the limits would
not move at all afterwards.  Repair.

Backpatch to 13 where the feature was introduced.

Author: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Reported-by: Marcin Krupowicz <mk@071.ovh>
Discussion: https://postgr.es/m/17103-004130e8f27782c9@postgresql.org
This commit is contained in:
Alvaro Herrera
2021-07-16 12:07:30 -04:00
parent 46111fb7b5
commit ead9e51e82
4 changed files with 74 additions and 12 deletions
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26
src/backend/replication/slot.c
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@@ -1143,11 +1143,14 @@ ReplicationSlotReserveWal(void)
* Returns whether ReplicationSlotControlLock was released in the interim (and
* in that case we're not holding the lock at return, otherwise we are).
*
* Sets *invalidated true if the slot was invalidated. (Untouched otherwise.)
*
* This is inherently racy, because we release the LWLock
* for syscalls, so caller must restart if we return true.
*/
static bool
InvalidatePossiblyObsoleteSlot(ReplicationSlot *s, XLogRecPtr oldestLSN)
InvalidatePossiblyObsoleteSlot(ReplicationSlot *s, XLogRecPtr oldestLSN,
bool *invalidated)
{
int last_signaled_pid = 0;
bool released_lock = false;
@@ -1204,6 +1207,9 @@ InvalidatePossiblyObsoleteSlot(ReplicationSlot *s, XLogRecPtr oldestLSN)
s->active_pid = MyProcPid;
s->data.invalidated_at = restart_lsn;
s->data.restart_lsn = InvalidXLogRecPtr;
/* Let caller know */
*invalidated = true;
}
SpinLockRelease(&s->mutex);
@@ -1291,12 +1297,15 @@ InvalidatePossiblyObsoleteSlot(ReplicationSlot *s, XLogRecPtr oldestLSN)
* Mark any slot that points to an LSN older than the given segment
* as invalid; it requires WAL that's about to be removed.
*
* Returns true when any slot have got invalidated.
*
* NB - this runs as part of checkpoint, so avoid raising errors if possible.
*/
void
bool
InvalidateObsoleteReplicationSlots(XLogSegNo oldestSegno)
{
XLogRecPtr oldestLSN;
bool invalidated = false;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -1309,13 +1318,24 @@ restart:
if (!s->in_use)
continue;
if (InvalidatePossiblyObsoleteSlot(s, oldestLSN))
if (InvalidatePossiblyObsoleteSlot(s, oldestLSN, &invalidated))
{
/* if the lock was released, start from scratch */
goto restart;
}
}
LWLockRelease(ReplicationSlotControlLock);
/*
* If any slots have been invalidated, recalculate the resource limits.
*/
if (invalidated)
{
ReplicationSlotsComputeRequiredXmin(false);
ReplicationSlotsComputeRequiredLSN();
}
return invalidated;
}
/*