Movatterモバイル変換

[0]ホーム
URL:

Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly

 Sign up
Appearance settings

Commitb36fbd9

Browse files
committed
Improve consistency of replication slot statistics
The replication slot stats stored in shared memory rely on an internalindex number. Both pgstat_reset_replslot() and pgstat_fetch_replslot()lacked some LWLock protections with ReplicationSlotControlLock whileoperating on these index numbers. This issue could cause these twofunctions to potentially operate on incorrect slots when taken inisolation in the event of slots dropped and/or re-created concurrently.Note that pg_stat_get_replication_slot() is called once per slot whenquerying pg_stat_replication_slots, meaning that the stats are retrievedacross multiple ReplicationSlotControlLock acquisitions. So, while thiscommit improves more consistency, it may still be possible thatstatistics are not completely consistent for a single scan ofpg_stat_replication_slots under concurrent replication slot drop orcreation activity.The issue should unlikely be a problem in practice, causing the reportof inconsistent stats or or the stats reset of an incorrect slot, so nobackpatch is done.Author: Bertrand DrouvotReviewed-by: Heikki Linnakangas, Shveta Malik, Michael PaquierDiscussion:https://postgr.es/m/ZeGq1HDWFfLkjh4o@ip-10-97-1-34.eu-west-3.compute.internal
1 parentf500ba0 commitb36fbd9

File tree

1 file changed

+25
-17
lines changed

1 file changed

+25
-17
lines changed

‎src/backend/utils/activity/pgstat_replslot.c

Lines changed: 25 additions & 17 deletions
Original file line numberDiff line numberDiff line change
@@ -29,7 +29,7 @@
2929
#include"utils/pgstat_internal.h"
3030

3131

32-
staticintget_replslot_index(constchar*name);
32+
staticintget_replslot_index(constchar*name,boolneed_lock);
3333

3434

3535
/*
@@ -45,8 +45,10 @@ pgstat_reset_replslot(const char *name)
4545

4646
Assert(name!=NULL);
4747

48+
LWLockAcquire(ReplicationSlotControlLock,LW_SHARED);
49+
4850
/* Check if the slot exits with the given name. */
49-
slot=SearchNamedReplicationSlot(name,true);
51+
slot=SearchNamedReplicationSlot(name,false);
5052

5153
if (!slot)
5254
ereport(ERROR,
@@ -55,15 +57,14 @@ pgstat_reset_replslot(const char *name)
5557
name)));
5658

5759
/*
58-
*Nothing to do for physical slots as we collect stats only forlogical
59-
* slots.
60+
*Reset stats if it is a logical slot. Nothing to do forphysical slots
61+
*as we collect stats only for logicalslots.
6062
*/
61-
if (SlotIsPhysical(slot))
62-
return;
63+
if (SlotIsLogical(slot))
64+
pgstat_reset(PGSTAT_KIND_REPLSLOT,InvalidOid,
65+
ReplicationSlotIndex(slot));
6366

64-
/* reset this one entry */
65-
pgstat_reset(PGSTAT_KIND_REPLSLOT,InvalidOid,
66-
ReplicationSlotIndex(slot));
67+
LWLockRelease(ReplicationSlotControlLock);
6768
}
6869

6970
/*
@@ -163,13 +164,20 @@ pgstat_drop_replslot(ReplicationSlot *slot)
163164
PgStat_StatReplSlotEntry*
164165
pgstat_fetch_replslot(NameDataslotname)
165166
{
166-
intidx=get_replslot_index(NameStr(slotname));
167+
intidx;
168+
PgStat_StatReplSlotEntry*slotentry=NULL;
167169

168-
if (idx==-1)
169-
returnNULL;
170+
LWLockAcquire(ReplicationSlotControlLock,LW_SHARED);
171+
172+
idx=get_replslot_index(NameStr(slotname), false);
173+
174+
if (idx!=-1)
175+
slotentry= (PgStat_StatReplSlotEntry*)pgstat_fetch_entry(PGSTAT_KIND_REPLSLOT,
176+
InvalidOid,idx);
177+
178+
LWLockRelease(ReplicationSlotControlLock);
170179

171-
return (PgStat_StatReplSlotEntry*)
172-
pgstat_fetch_entry(PGSTAT_KIND_REPLSLOT,InvalidOid,idx);
180+
returnslotentry;
173181
}
174182

175183
void
@@ -188,7 +196,7 @@ pgstat_replslot_to_serialized_name_cb(const PgStat_HashKey *key, const PgStatSha
188196
bool
189197
pgstat_replslot_from_serialized_name_cb(constNameData*name,PgStat_HashKey*key)
190198
{
191-
intidx=get_replslot_index(NameStr(*name));
199+
intidx=get_replslot_index(NameStr(*name), true);
192200

193201
/* slot might have been deleted */
194202
if (idx==-1)
@@ -208,13 +216,13 @@ pgstat_replslot_reset_timestamp_cb(PgStatShared_Common *header, TimestampTz ts)
208216
}
209217

210218
staticint
211-
get_replslot_index(constchar*name)
219+
get_replslot_index(constchar*name,boolneed_lock)
212220
{
213221
ReplicationSlot*slot;
214222

215223
Assert(name!=NULL);
216224

217-
slot=SearchNamedReplicationSlot(name,true);
225+
slot=SearchNamedReplicationSlot(name,need_lock);
218226

219227
if (!slot)
220228
return-1;

0 commit comments

Comments
 (0)
[8]ページ先頭
©2009-2025 Movatter.jp