Обсуждение: BUG #16016: deadlock with startup process, AccessExclusiveLock on pg_statistic's toast table
BUG #16016: deadlock with startup process, AccessExclusiveLock on pg_statistic's toast table
От
PG Bug reporting form
Дата:
The following bug has been logged on the website:
Bug reference: 16016
Logged by: Alexey Ermakov
Email address: alexey.ermakov@dataegret.com
PostgreSQL version: 11.5
Operating system: Ubuntu 16.04.6 LTS
Description:
Hello,
recently I encountered strange situation when replica server stopped serving
queries. most likely it happened because startup process was holding access
exclusive lock on pg_statistic's toast table and was waiting for some
backend which lead to deadlock.
situation resolved after max_standby_streaming_delay timeout kicked in and
conflicting backend's queries were canceled.
more details:
1) first waiting backend in logs:
2019-09-19 12:14:11.314 UTC 144285 user@db from [local] [vxid:21/106350189
txid:0] [BIND waiting] LOG: process 144285 still waiting for
AccessShareLock on relation 2840 of database 16389 after 1000.115 ms
2019-09-19 12:14:11.314 UTC 144285 user@db from [local] [vxid:21/106350189
txid:0] [BIND waiting] DETAIL: Process holding the lock: 6002. Wait queue:
144285, 136649, 127349, 76417, 97350, 93019, 109010, 103163, 136300.
2) 6002 pid is indeed startup process:
ps ax | grep 6002
6002 ? Ss 200:16 postgres: 11/main: startup recovering
000000010000425900000094
3) locked relation is pg_statistic's toast table:
select 2840::regclass;
regclass
------------------------
pg_toast.pg_toast_2619
select 2619::regclass;
regclass
--------------
pg_statistic
4) I guess autovacuum was working on pg_statistic table on master server
right before problem occurred and cleaned up some pages at the end of
relation.
but can't confirm, log_autovacuum_min_duration = 1s and no entries in logs,
but table is pretty small (~2MB) so autovacuum might be finished in less
than 1s.
5) according to client no DB migrations were performed at that time.
same thing (again toast table of pg_statistic) also happened year ago twice
on 9.6.6 version on completely different server and project.
unfortunately I wasn't able to get gdb backtrace of startup process, so it
might be difficult to understand where it got stuck :(
at year's ago case I was able to get output of pg_locks, but not much
interesting there:
select * from pg_locks;
locktype | database | relation | page | tuple | virtualxid |
transactionid | classid | objid | objsubid | virtualtransaction | pid |
mode | granted | fastpath
------------+----------+----------+------+-------+-------------+---------------+---------+-------+----------+--------------------+--------+---------------------+---------+----------
...truncated, I can show full output if it might help...
virtualxid | | | | | 12/19089055 |
| | | | 12/19089055 | 91145 | ExclusiveLock
| t | t
virtualxid | | | | | 1/1 |
| | | | 1/0 | 16141 | ExclusiveLock
| t | t
relation | 20508 | 2840 | | | |
| | | | 12/19089055 | 91145 |
AccessShareLock | f | f
relation | 20508 | 2840 | | | |
| | | | 24/18427740 | 94698 |
AccessShareLock | f | f
relation | 20508 | 2840 | | | |
| | | | 26/15964159 | 96387 |
AccessShareLock | f | f
relation | 20508 | 2840 | | | |
| | | | 27/11337343 | 107448 |
AccessShareLock | f | f
relation | 20508 | 2840 | | | |
| | | | 28/9666022 | 99110 |
AccessShareLock | f | f
relation | 20508 | 2840 | | | |
| | | | 1/0 | 16141 |
AccessExclusiveLock | t | f
(56 rows)
in that case pid 16141 - startup process and again 2840 - oid of toast table
of pg_statistic.
16141 ? Ss 14169:14 postgres: 9.6/main: startup process
recovering 000000020000A3E3000000DC waiting
--
Thanks,
Alexey Ermakov
Re: BUG #16016: deadlock with startup process, AccessExclusiveLock on pg_statistic's toast table
От
Sergei Kornilov
Дата:
Hello Seems I have testcase for this report: primary + streaming replica with such settings: log_lock_waits = 'on' max_standby_streaming_delay = '-1' fsync = off synchronous_commit = off (seems this is rare race condition and I can't catch on slow fsync) Create some table for queries: create table tablename as select generate_series(1,100) as i; Run on primary: pgbench -f primary.sql -c 1 -t 100000 --port 5555 postgres primary.sql is: vacuum full pg_statistic; vacuum full tablename; (some activity with AccessExclusiveLock) On replica: pgbench -f ro.sql --time=300 -n -c 20 --port 5556 postgres Script content: \set i random(1,100) select * from tablename where i = :i; Usually replica kills queries with ERROR: deadlock detected and pgbench stops. But sometimes (usually less than 5-10 timeson my host) both startup and backend with running query will start waiting something. Also new connections may becomein "startup waiting" status indefinitely. With another max_standby_streaming_delay queries are killed, but only after this timeout (as reported in this bug report).I think this should be detected as deadlock but not happens for some reason. regards, Sergei
Sergei Kornilov <sk@zsrv.org> writes:
> Seems I have testcase for this report:
If you have a test case, could you collect stack traces from each
of the stuck processes? That would eliminate a lot of hypothesizing.
regards, tom lane
Re: BUG #16016: deadlock with startup process, AccessExclusiveLockon pg_statistic's toast table
От
Alexey Ermakov
Дата:
Hello,
On 9/23/19 01:06, Tom Lane wrote:
> If you have a test case, could you collect stack traces from each
> of the stuck processes? That would eliminate a lot of hypothesizing.
>
> regards, tom lane
I reproduced Sergei's test case on postgresql 11.5, replica hung up
almost immediately after pgbench ran.
9907 - pid of startup process, 16387 - oid of test table, 2619 - oid of
pg_statistic, 2840 - oid of toast table of pg_statistic.
1) pgbench on replica with 1 concurrent processes (-c 1):
this case looks a bit different from what happened on initial report
(which recently happened again btw) because at this time I can't even
open new connection via psql or run query with pg_stat_activity - in
hangs (pg_locks query works).
perhaps because this time access exclusive lock is on pg_statistic table
too, not only on it's toast table.
select * from pg_locks;
locktype | database | relation | page | tuple | virtualxid |
transactionid | classid | objid | objsubid | virtualtransaction | pid
| mode | granted | fastpath
------------+----------+----------+------+-------+------------+---------------+---------+-------+----------+--------------------+-------+---------------------+---------+----------
relation | 13217 | 11645 | | | |
| | | | 2/73518 | 17266 | AccessShareLock |
t | t
virtualxid | | | | | 2/73518
| | | | | 2/73518 | 17266 |
ExclusiveLock | t | t
virtualxid | | | | | 3/4590466
| | | | | 3/4590466 | 32074 |
ExclusiveLock | t | t
virtualxid | | | | | 1/1 |
| | | | 1/0 | 9907 | ExclusiveLock |
t | t
relation | 13217 | 2841 | | | |
| | | | 1/0 | 9907 | AccessExclusiveLock |
t | f
relation | 13217 | 2619 | | | |
| | | | 3/4590466 | 32074 | AccessShareLock |
f | f
relation | 13217 | 2840 | | | |
| | | | 1/0 | 9907 | AccessExclusiveLock |
t | f
relation | 13217 | 5364206 | | | |
| | | | 1/0 | 9907 | AccessExclusiveLock |
t | f
relation | 13217 | 2619 | | | |
| | | | 1/0 | 9907 | AccessExclusiveLock |
t | f
relation | 13217 | 5364204 | | | |
| | | | 1/0 | 9907 | AccessExclusiveLock |
t | f
relation | 13217 | 16387 | | | |
| | | | 3/4590466 | 32074 | AccessShareLock |
t | f
relation | 13217 | 5364201 | | | |
| | | | 1/0 | 9907 | AccessExclusiveLock |
t | f
(12 rows)
stack trace of startup process 9907:
#0 0x00007fdff4a025b3 in __select_nocancel () at
../sysdeps/unix/syscall-template.S:84
#1 0x00005608fde0c6cd in pg_usleep (microsec=<optimized out>) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/port/pgsleep.c:56
#2 0x00005608fdc94126 in WaitExceedsMaxStandbyDelay () at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/storage/ipc/standby.c:201
#3 ResolveRecoveryConflictWithVirtualXIDs (waitlist=0x5608fe46a450,
reason=reason@entry=PROCSIG_RECOVERY_CONFLICT_SNAPSHOT) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/storage/ipc/standby.c:262
#4 0x00005608fdc9434a in ResolveRecoveryConflictWithVirtualXIDs
(reason=PROCSIG_RECOVERY_CONFLICT_SNAPSHOT, waitlist=<optimized out>) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/storage/ipc/standby.c:315
#5 ResolveRecoveryConflictWithSnapshot (latestRemovedXid=<optimized
out>, node=...) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/storage/ipc/standby.c:313
#6 0x00005608fda04ddc in heap_xlog_clean (record=0x5608fe426578) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/access/heap/heapam.c:8238
#7 heap2_redo (record=0x5608fe426578) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/access/heap/heapam.c:9391
#8 0x00005608fda4b974 in StartupXLOG () at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/access/transam/xlog.c:7306
#9 0x00005608fdc3b4d3 in StartupProcessMain () at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/postmaster/startup.c:211
#10 0x00005608fda5b763 in AuxiliaryProcessMain (argc=argc@entry=2,
argv=argv@entry=0x7ffc9277c7e0) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/bootstrap/bootstrap.c:441
#11 0x00005608fdc381e3 in StartChildProcess (type=StartupProcess) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/postmaster/postmaster.c:5337
#12 0x00005608fdc3af5e in PostmasterMain (argc=5, argv=<optimized out>)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/postmaster/postmaster.c:1372
#13 0x00005608fd9c0075 in main (argc=5, argv=0x5608fe425820) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/main/main.c:228
stack trace of backend 32074:
#0 0x00007fdff4a0c9f3 in __epoll_wait_nocancel () at
../sysdeps/unix/syscall-template.S:84
#1 0x00005608fdc8cb51 in WaitEventSetWaitBlock (nevents=1,
occurred_events=0x7ffc9277a6f0, cur_timeout=-1, set=0x5608fe42bed8) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/storage/ipc/latch.c:1048
#2 WaitEventSetWait (set=set@entry=0x5608fe42bed8,
timeout=timeout@entry=-1,
occurred_events=occurred_events@entry=0x7ffc9277a6f0,
nevents=nevents@entry=1, wait_event_info=wait_event_info@entry=50331648)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/storage/ipc/latch.c:1000
#3 0x00005608fdc8cfc4 in WaitLatchOrSocket (latch=0x7fdfebbf1594,
wakeEvents=wakeEvents@entry=1, sock=sock@entry=-1, timeout=-1,
timeout@entry=0, wait_event_info=50331648)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/storage/ipc/latch.c:385
#4 0x00005608fdc8d075 in WaitLatch (latch=<optimized out>,
wakeEvents=wakeEvents@entry=1, timeout=timeout@entry=0,
wait_event_info=<optimized out>)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/storage/ipc/latch.c:339
#5 0x00005608fdc9d591 in ProcSleep
(locallock=locallock@entry=0x5608fe4488e0,
lockMethodTable=lockMethodTable@entry=0x5608fe2321e0 <default_lockmethod>)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/storage/lmgr/proc.c:1272
#6 0x00005608fdc97c99 in WaitOnLock
(locallock=locallock@entry=0x5608fe4488e0,
owner=owner@entry=0x5608fe474370) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/storage/lmgr/lock.c:1744
#7 0x00005608fdc98fe1 in LockAcquireExtended
(locktag=locktag@entry=0x7ffc9277aac0, lockmode=lockmode@entry=1,
sessionLock=sessionLock@entry=false, dontWait=dontWait@entry=false,
reportMemoryError=reportMemoryError@entry=true,
locallockp=locallockp@entry=0x7ffc9277aab8) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/storage/lmgr/lock.c:1026
#8 0x00005608fdc96648 in LockRelationOid (relid=2619, lockmode=1) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/storage/lmgr/lmgr.c:113
#9 0x00005608fd9fb4cd in relation_open (relationId=2619,
lockmode=<optimized out>) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/access/heap/heapam.c:1132
#10 0x00005608fd9fb6de in heap_open (relationId=<optimized out>,
lockmode=lockmode@entry=1) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/access/heap/heapam.c:1298
#11 0x00005608fddafb81 in SearchCatCacheMiss
(cache=cache@entry=0x5608fe498500, nkeys=nkeys@entry=3,
hashValue=hashValue@entry=2374461275, hashIndex=hashIndex@entry=91,
v1=v1@entry=16387, v2=v2@entry=1, v3=0, v4=0)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/utils/cache/catcache.c:1375
#12 0x00005608fddb093f in SearchCatCacheInternal (v4=0, v3=0,
v2=<optimized out>, v1=<optimized out>, nkeys=3, cache=0x5608fe498500)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/utils/cache/catcache.c:1317
#13 SearchCatCache3 (cache=0x5608fe498500, v1=16387, v2=1, v3=0) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/utils/cache/catcache.c:1201
#14 0x00005608fddc2f18 in SearchSysCache3 (cacheId=cacheId@entry=57,
key1=<optimized out>, key2=<optimized out>, key3=<optimized out>) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/utils/cache/syscache.c:1141
#15 0x00005608fdd76ca6 in examine_simple_variable (var=<optimized out>,
var=<optimized out>, vardata=0x7ffc9277aeb0, root=<optimized out>) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/utils/adt/selfuncs.c:5037
#16 examine_variable (root=root@entry=0x5608fe4f5fd8, node=<optimized
out>, varRelid=varRelid@entry=0, vardata=vardata@entry=0x7ffc9277aeb0)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/utils/adt/selfuncs.c:4821
#17 0x00005608fdd772c7 in get_restriction_variable (root=0x5608fe4f5fd8,
args=<optimized out>, varRelid=0, vardata=0x7ffc9277aeb0,
other=0x7ffc9277aea8, varonleft=0x7ffc9277aea6)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/utils/adt/selfuncs.c:4683
#18 0x00005608fdd783f6 in eqsel_internal (fcinfo=<optimized out>,
negate=negate@entry=false) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/utils/adt/selfuncs.c:279
#19 0x00005608fdd786eb in eqsel (fcinfo=<optimized out>) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/utils/adt/selfuncs.c:243
#20 0x00005608fddd1cf5 in OidFunctionCall4Coll (functionId=<optimized
out>, collation=collation@entry=0, arg1=arg1@entry=94596626341848,
arg2=arg2@entry=96, arg3=arg3@entry=94596626343080, arg4=arg4@entry=0)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/utils/fmgr/fmgr.c:1501
#21 0x00005608fdc1c07d in restriction_selectivity
(root=root@entry=0x5608fe4f5fd8, operatorid=96, args=0x5608fe4f64a8,
inputcollid=0, varRelid=varRelid@entry=0)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/optimizer/util/plancat.c:1813
#22 0x00005608fdbdba11 in clause_selectivity
(root=root@entry=0x5608fe4f5fd8, clause=<optimized out>,
varRelid=varRelid@entry=0, jointype=jointype@entry=JOIN_INNER,
sjinfo=sjinfo@entry=0x0)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/optimizer/path/clausesel.c:748
#23 0x00005608fdbdbbcb in clauselist_selectivity
(root=root@entry=0x5608fe4f5fd8, clauses=0x5608fe4f6d38,
varRelid=varRelid@entry=0, jointype=jointype@entry=JOIN_INNER,
sjinfo=sjinfo@entry=0x0)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/optimizer/path/clausesel.c:117
#24 0x00005608fdbe19b1 in set_baserel_size_estimates
(root=root@entry=0x5608fe4f5fd8, rel=rel@entry=0x5608fe4f6628) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/optimizer/path/costsize.c:4308
#25 0x00005608fdbda64c in set_plain_rel_size (rte=<optimized out>,
rel=0x5608fe4f6628, root=0x5608fe4f5fd8) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/optimizer/path/allpaths.c:532
#26 set_rel_size (root=root@entry=0x5608fe4f5fd8,
rel=rel@entry=0x5608fe4f6628, rti=rti@entry=1, rte=<optimized out>) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/optimizer/path/allpaths.c:369
#27 0x00005608fdbdb37e in set_base_rel_sizes (root=<optimized out>) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/optimizer/path/allpaths.c:281
#28 make_one_rel (root=root@entry=0x5608fe4f5fd8,
joinlist=joinlist@entry=0x5608fe4f69d8) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/optimizer/path/allpaths.c:179
#29 0x00005608fdbfa130 in query_planner (root=root@entry=0x5608fe4f5fd8,
tlist=tlist@entry=0x5608fe4f6408,
qp_callback=qp_callback@entry=0x5608fdbfb530 <standard_qp_callback>,
qp_extra=qp_extra@entry=0x7ffc9277b760)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/optimizer/plan/planmain.c:265
#30 0x00005608fdbfe94b in grouping_planner
(root=root@entry=0x5608fe4f5fd8,
inheritance_update=inheritance_update@entry=false,
tuple_fraction=<optimized out>, tuple_fraction@entry=0)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/optimizer/plan/planner.c:1942
#31 0x00005608fdc00d36 in subquery_planner
(glob=glob@entry=0x5608fe42c128, parse=parse@entry=0x5608fe42bb38,
parent_root=parent_root@entry=0x0,
hasRecursion=hasRecursion@entry=false,
tuple_fraction=tuple_fraction@entry=0)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/optimizer/plan/planner.c:966
#32 0x00005608fdc01d15 in standard_planner (parse=0x5608fe42bb38,
cursorOptions=256, boundParams=<optimized out>) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/optimizer/plan/planner.c:405
#33 0x00005608fdcaec59 in pg_plan_query
(querytree=querytree@entry=0x5608fe42bb38,
cursorOptions=cursorOptions@entry=256, boundParams=boundParams@entry=0x0)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/tcop/postgres.c:832
#34 0x00005608fdcaed36 in pg_plan_queries (querytrees=<optimized out>,
cursorOptions=cursorOptions@entry=256,
boundParams=boundParams@entry=0x0) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/tcop/postgres.c:898
#35 0x00005608fdcaf267 in exec_simple_query (query_string=0x5608fe42ab10
"select * from tablename where i = 6;") at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/tcop/postgres.c:1073
#36 0x00005608fdcb064b in PostgresMain (argc=<optimized out>,
argv=argv@entry=0x5608fe472900, dbname=0x5608fe472858 "postgres",
username=<optimized out>)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/tcop/postgres.c:4182
#37 0x00005608fd9becd2 in BackendRun (port=0x5608fe46b070) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/postmaster/postmaster.c:4358
#38 BackendStartup (port=0x5608fe46b070) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/postmaster/postmaster.c:4030
#39 ServerLoop () at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/postmaster/postmaster.c:1707
#40 0x00005608fdc3af82 in PostmasterMain (argc=5, argv=<optimized out>)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/postmaster/postmaster.c:1380
#41 0x00005608fd9c0075 in main (argc=5, argv=0x5608fe425820) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/main/main.c:228
2) pgbench on replica with 2 concurrent processes (-c 2):
this case also looks a bit different from initial report, here we have
AccessExclusiveLock on test table, not on pg_statistic's toast table:
select * from pg_stat_activity (both backend connections are waiting
until max_standby_streaming_delay timeout happened):
...
-[ RECORD 2 ]----+--------------------------------------
datid | 13217
datname | postgres
pid | 21152
usesysid | 10
usename | postgres
application_name | pgbench
client_addr |
client_hostname |
client_port | -1
backend_start | 2019-11-01 13:00:59.910532+06
xact_start | 2019-11-01 13:01:08.160028+06
query_start | 2019-11-01 13:01:08.160028+06
state_change | 2019-11-01 13:01:08.160029+06
wait_event_type | Lock
wait_event | relation
state | active
backend_xid |
backend_xmin | 473235
query | select * from tablename where i = 89;
backend_type | client backend
-[ RECORD 3 ]----+--------------------------------------
datid | 13217
datname | postgres
pid | 21153
usesysid | 10
usename | postgres
application_name | pgbench
client_addr |
client_hostname |
client_port | -1
backend_start | 2019-11-01 13:00:59.913201+06
xact_start | 2019-11-01 13:01:08.159873+06
query_start | 2019-11-01 13:01:08.159873+06
state_change | 2019-11-01 13:01:08.159873+06
wait_event_type | Lock
wait_event | relation
state | active
backend_xid |
backend_xmin | 473235
query | select * from tablename where i = 72;
backend_type | client backend
-[ RECORD 4 ]----+--------------------------------------
datid |
datname |
pid | 9907
usesysid |
usename |
application_name |
client_addr |
client_hostname |
client_port |
backend_start | 2019-10-31 19:11:55.514707+06
xact_start |
query_start |
state_change |
wait_event_type |
wait_event |
state |
backend_xid |
backend_xmin |
query |
backend_type | startup
...
select * from pg_locks:
locktype | database | relation | page | tuple | virtualxid |
transactionid | classid | objid | objsubid | virtualtransaction | pid
| mode | granted | fastpath
------------+----------+----------+------+-------+------------+---------------+---------+-------+----------+--------------------+-------+---------------------+---------+----------
relation | 13217 | 11645 | | | |
| | | | 2/30436 | 17266 |
AccessShareLock | t | t
virtualxid | | | | | 2/30436
| | | | | 2/30436 |
17266 | ExclusiveLock | t | t
virtualxid | | | | | 4/2366585
| | | | | 4/2366585 |
21153 | ExclusiveLock | t | t
virtualxid | | | | | 3/2624520
| | | | | 3/2624520 |
21152 | ExclusiveLock | t | t
virtualxid | | | | | 1/1
| | | | | 1/0 |
9907 | ExclusiveLock | t | t
relation | 13217 | 16387 | | | |
| | | | 1/0 | 9907 |
AccessExclusiveLock | t | f
relation | 13217 | 16387 | | | |
| | | | 3/2624520 | 21152 |
AccessShareLock | f | f
relation | 13217 | 16387 | | | |
| | | | 4/2366585 | 21153 |
AccessShareLock | f | f
(8 rows)
stack trace of startup process 9907:
#0 0x00007fdff4a025b3 in __select_nocancel () at
../sysdeps/unix/syscall-template.S:84
#1 0x00005608fde0c6cd in pg_usleep (microsec=<optimized out>) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/port/pgsleep.c:56
#2 0x00005608fdc94126 in WaitExceedsMaxStandbyDelay () at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/storage/ipc/standby.c:201
#3 ResolveRecoveryConflictWithVirtualXIDs (waitlist=0x5608fe46a450,
reason=reason@entry=PROCSIG_RECOVERY_CONFLICT_SNAPSHOT) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/storage/ipc/standby.c:262
#4 0x00005608fdc9434a in ResolveRecoveryConflictWithVirtualXIDs
(reason=PROCSIG_RECOVERY_CONFLICT_SNAPSHOT, waitlist=<optimized out>) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/storage/ipc/standby.c:315
#5 ResolveRecoveryConflictWithSnapshot
(latestRemovedXid=latestRemovedXid@entry=473242, node=...) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/storage/ipc/standby.c:313
#6 0x00005608fda1d8b2 in btree_xlog_delete (record=0x5608fe426578) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/access/nbtree/nbtxlog.c:703
#7 btree_redo (record=0x5608fe426578) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/access/nbtree/nbtxlog.c:1023
#8 0x00005608fda4b974 in StartupXLOG () at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/access/transam/xlog.c:7306
#9 0x00005608fdc3b4d3 in StartupProcessMain () at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/postmaster/startup.c:211
#10 0x00005608fda5b763 in AuxiliaryProcessMain (argc=argc@entry=2,
argv=argv@entry=0x7ffc9277c7e0) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/bootstrap/bootstrap.c:441
#11 0x00005608fdc381e3 in StartChildProcess (type=StartupProcess) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/postmaster/postmaster.c:5337
#12 0x00005608fdc3af5e in PostmasterMain (argc=5, argv=<optimized out>)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/postmaster/postmaster.c:1372
#13 0x00005608fd9c0075 in main (argc=5, argv=0x5608fe425820) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/main/main.c:228
backend 21153:
#0 0x00007fdff4a0c9f3 in __epoll_wait_nocancel () at
../sysdeps/unix/syscall-template.S:84
#1 0x00005608fdc8cb51 in WaitEventSetWaitBlock (nevents=1,
occurred_events=0x7ffc9277b1a0, cur_timeout=-1, set=0x5608fe42c8b8) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/storage/ipc/latch.c:1048
#2 WaitEventSetWait (set=set@entry=0x5608fe42c8b8,
timeout=timeout@entry=-1,
occurred_events=occurred_events@entry=0x7ffc9277b1a0,
nevents=nevents@entry=1, wait_event_info=wait_event_info@entry=50331648)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/storage/ipc/latch.c:1000
#3 0x00005608fdc8cfc4 in WaitLatchOrSocket (latch=0x7fdfebbf0ba4,
wakeEvents=wakeEvents@entry=1, sock=sock@entry=-1, timeout=-1,
timeout@entry=0, wait_event_info=50331648)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/storage/ipc/latch.c:385
#4 0x00005608fdc8d075 in WaitLatch (latch=<optimized out>,
wakeEvents=wakeEvents@entry=1, timeout=timeout@entry=0,
wait_event_info=<optimized out>)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/storage/ipc/latch.c:339
#5 0x00005608fdc9d591 in ProcSleep
(locallock=locallock@entry=0x5608fe448940,
lockMethodTable=lockMethodTable@entry=0x5608fe2321e0 <default_lockmethod>)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/storage/lmgr/proc.c:1272
#6 0x00005608fdc97c99 in WaitOnLock
(locallock=locallock@entry=0x5608fe448940,
owner=owner@entry=0x5608fe474370) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/storage/lmgr/lock.c:1744
#7 0x00005608fdc98fe1 in LockAcquireExtended
(locktag=locktag@entry=0x7ffc9277b570, lockmode=lockmode@entry=1,
sessionLock=sessionLock@entry=false, dontWait=dontWait@entry=false,
reportMemoryError=reportMemoryError@entry=true,
locallockp=locallockp@entry=0x7ffc9277b568) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/storage/lmgr/lock.c:1026
#8 0x00005608fdc96648 in LockRelationOid (relid=16387, lockmode=1) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/storage/lmgr/lmgr.c:113
#9 0x00005608fda6a4cd in RangeVarGetRelidExtended
(relation=0x5608fe42b650, lockmode=1, flags=1,
callback=callback@entry=0x0, callback_arg=callback_arg@entry=0x0)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/catalog/namespace.c:379
#10 0x00005608fd9fb629 in relation_openrv_extended (relation=<optimized
out>, lockmode=<optimized out>, missing_ok=<optimized out>) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/access/heap/heapam.c:1250
#11 0x00005608fd9fb841 in heap_openrv_extended
(relation=relation@entry=0x5608fe42b650, lockmode=lockmode@entry=1,
missing_ok=missing_ok@entry=true)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/access/heap/heapam.c:1358
#12 0x00005608fdac6049 in parserOpenTable (pstate=0x5608fe42ba28,
relation=0x5608fe42b650, lockmode=1) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/parser/parse_relation.c:1152
#13 0x00005608fdac7a6a in addRangeTableEntry
(pstate=pstate@entry=0x5608fe42ba28,
relation=relation@entry=0x5608fe42b650, alias=0x0, inh=<optimized out>,
inFromCl=inFromCl@entry=true)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/parser/parse_relation.c:1217
#14 0x00005608fdab2369 in transformTableEntry (r=0x5608fe42b650,
pstate=0x5608fe42ba28) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/parser/parse_clause.c:435
#15 transformFromClauseItem (pstate=pstate@entry=0x5608fe42ba28,
n=0x5608fe42b650, top_rte=top_rte@entry=0x7ffc9277b858,
top_rti=top_rti@entry=0x7ffc9277b854,
namespace=namespace@entry=0x7ffc9277b860)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/parser/parse_clause.c:1122
#16 0x00005608fdab3835 in transformFromClause
(pstate=pstate@entry=0x5608fe42ba28, frmList=<optimized out>) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/parser/parse_clause.c:139
#17 0x00005608fda90804 in transformSelectStmt (stmt=0x5608fe42b898,
pstate=0x5608fe42ba28) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/parser/analyze.c:1240
#18 transformStmt (pstate=pstate@entry=0x5608fe42ba28,
parseTree=0x5608fe42b898) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/parser/analyze.c:301
#19 0x00005608fda92550 in transformOptionalSelectInto
(pstate=pstate@entry=0x5608fe42ba28, parseTree=<optimized out>) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/parser/analyze.c:246
#20 0x00005608fda925d5 in transformTopLevelStmt
(pstate=pstate@entry=0x5608fe42ba28,
parseTree=parseTree@entry=0x5608fe42b9a8) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/parser/analyze.c:196
#21 0x00005608fda92648 in parse_analyze (parseTree=0x5608fe42b9a8,
sourceText=sourceText@entry=0x5608fe42ab10 "select * from tablename
where i = 72;", paramTypes=0x0, numParams=0, queryEnv=0x0)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/parser/analyze.c:116
#22 0x00005608fdcaeb07 in pg_analyze_and_rewrite
(parsetree=parsetree@entry=0x5608fe42b9a8,
query_string=query_string@entry=0x5608fe42ab10 "select * from tablename
where i = 72;", paramTypes=paramTypes@entry=0x0,
numParams=numParams@entry=0, queryEnv=queryEnv@entry=0x0) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/tcop/postgres.c:689
#23 0x00005608fdcaf258 in exec_simple_query (query_string=0x5608fe42ab10
"select * from tablename where i = 72;") at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/tcop/postgres.c:1070
#24 0x00005608fdcb064b in PostgresMain (argc=<optimized out>,
argv=argv@entry=0x5608fe472900, dbname=0x5608fe472858 "postgres",
username=<optimized out>)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/tcop/postgres.c:4182
#25 0x00005608fd9becd2 in BackendRun (port=0x5608fe46b070) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/postmaster/postmaster.c:4358
#26 BackendStartup (port=0x5608fe46b070) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/postmaster/postmaster.c:4030
#27 ServerLoop () at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/postmaster/postmaster.c:1707
#28 0x00005608fdc3af82 in PostmasterMain (argc=5, argv=<optimized out>)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/postmaster/postmaster.c:1380
#29 0x00005608fd9c0075 in main (argc=5, argv=0x5608fe425820) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/main/main.c:228
backend 21152 (looks the same):
#0 0x00007fdff4a0c9f3 in __epoll_wait_nocancel () at
../sysdeps/unix/syscall-template.S:84
#1 0x00005608fdc8cb51 in WaitEventSetWaitBlock (nevents=1,
occurred_events=0x7ffc9277b1a0, cur_timeout=-1, set=0x5608fe42c8b8) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/storage/ipc/latch.c:1048
#2 WaitEventSetWait (set=set@entry=0x5608fe42c8b8,
timeout=timeout@entry=-1,
occurred_events=occurred_events@entry=0x7ffc9277b1a0,
nevents=nevents@entry=1, wait_event_info=wait_event_info@entry=50331648)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/storage/ipc/latch.c:1000
#3 0x00005608fdc8cfc4 in WaitLatchOrSocket (latch=0x7fdfebbf1244,
wakeEvents=wakeEvents@entry=1, sock=sock@entry=-1, timeout=-1,
timeout@entry=0, wait_event_info=50331648)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/storage/ipc/latch.c:385
#4 0x00005608fdc8d075 in WaitLatch (latch=<optimized out>,
wakeEvents=wakeEvents@entry=1, timeout=timeout@entry=0,
wait_event_info=<optimized out>)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/storage/ipc/latch.c:339
#5 0x00005608fdc9d591 in ProcSleep
(locallock=locallock@entry=0x5608fe448940,
lockMethodTable=lockMethodTable@entry=0x5608fe2321e0 <default_lockmethod>)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/storage/lmgr/proc.c:1272
#6 0x00005608fdc97c99 in WaitOnLock
(locallock=locallock@entry=0x5608fe448940,
owner=owner@entry=0x5608fe474370) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/storage/lmgr/lock.c:1744
#7 0x00005608fdc98fe1 in LockAcquireExtended
(locktag=locktag@entry=0x7ffc9277b570, lockmode=lockmode@entry=1,
sessionLock=sessionLock@entry=false, dontWait=dontWait@entry=false,
reportMemoryError=reportMemoryError@entry=true,
locallockp=locallockp@entry=0x7ffc9277b568) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/storage/lmgr/lock.c:1026
#8 0x00005608fdc96648 in LockRelationOid (relid=16387, lockmode=1) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/storage/lmgr/lmgr.c:113
#9 0x00005608fda6a4cd in RangeVarGetRelidExtended
(relation=0x5608fe42b650, lockmode=1, flags=1,
callback=callback@entry=0x0, callback_arg=callback_arg@entry=0x0)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/catalog/namespace.c:379
#10 0x00005608fd9fb629 in relation_openrv_extended (relation=<optimized
out>, lockmode=<optimized out>, missing_ok=<optimized out>) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/access/heap/heapam.c:1250
#11 0x00005608fd9fb841 in heap_openrv_extended
(relation=relation@entry=0x5608fe42b650, lockmode=lockmode@entry=1,
missing_ok=missing_ok@entry=true)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/access/heap/heapam.c:1358
#12 0x00005608fdac6049 in parserOpenTable (pstate=0x5608fe42ba28,
relation=0x5608fe42b650, lockmode=1) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/parser/parse_relation.c:1152
#13 0x00005608fdac7a6a in addRangeTableEntry
(pstate=pstate@entry=0x5608fe42ba28,
relation=relation@entry=0x5608fe42b650, alias=0x0, inh=<optimized out>,
inFromCl=inFromCl@entry=true)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/parser/parse_relation.c:1217
#14 0x00005608fdab2369 in transformTableEntry (r=0x5608fe42b650,
pstate=0x5608fe42ba28) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/parser/parse_clause.c:435
#15 transformFromClauseItem (pstate=pstate@entry=0x5608fe42ba28,
n=0x5608fe42b650, top_rte=top_rte@entry=0x7ffc9277b858,
top_rti=top_rti@entry=0x7ffc9277b854,
namespace=namespace@entry=0x7ffc9277b860)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/parser/parse_clause.c:1122
#16 0x00005608fdab3835 in transformFromClause
(pstate=pstate@entry=0x5608fe42ba28, frmList=<optimized out>) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/parser/parse_clause.c:139
#17 0x00005608fda90804 in transformSelectStmt (stmt=0x5608fe42b898,
pstate=0x5608fe42ba28) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/parser/analyze.c:1240
#18 transformStmt (pstate=pstate@entry=0x5608fe42ba28,
parseTree=0x5608fe42b898) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/parser/analyze.c:301
#19 0x00005608fda92550 in transformOptionalSelectInto
(pstate=pstate@entry=0x5608fe42ba28, parseTree=<optimized out>) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/parser/analyze.c:246
#20 0x00005608fda925d5 in transformTopLevelStmt
(pstate=pstate@entry=0x5608fe42ba28,
parseTree=parseTree@entry=0x5608fe42b9a8) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/parser/analyze.c:196
#21 0x00005608fda92648 in parse_analyze (parseTree=0x5608fe42b9a8,
sourceText=sourceText@entry=0x5608fe42ab10 "select * from tablename
where i = 89;", paramTypes=0x0, numParams=0, queryEnv=0x0)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/parser/analyze.c:116
#22 0x00005608fdcaeb07 in pg_analyze_and_rewrite
(parsetree=parsetree@entry=0x5608fe42b9a8,
query_string=query_string@entry=0x5608fe42ab10 "select * from tablename
where i = 89;", paramTypes=paramTypes@entry=0x0,
numParams=numParams@entry=0, queryEnv=queryEnv@entry=0x0) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/tcop/postgres.c:689
#23 0x00005608fdcaf258 in exec_simple_query (query_string=0x5608fe42ab10
"select * from tablename where i = 89;") at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/tcop/postgres.c:1070
#24 0x00005608fdcb064b in PostgresMain (argc=<optimized out>,
argv=argv@entry=0x5608fe472900, dbname=0x5608fe472858 "postgres",
username=<optimized out>)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/tcop/postgres.c:4182
#25 0x00005608fd9becd2 in BackendRun (port=0x5608fe46b070) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/postmaster/postmaster.c:4358
#26 BackendStartup (port=0x5608fe46b070) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/postmaster/postmaster.c:4030
#27 ServerLoop () at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/postmaster/postmaster.c:1707
#28 0x00005608fdc3af82 in PostmasterMain (argc=5, argv=<optimized out>)
at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/postmaster/postmaster.c:1380
#29 0x00005608fd9c0075 in main (argc=5, argv=0x5608fe425820) at
/build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/main/main.c:228
Hope that will help, I'll try to reproduce issue without vacuum full, so
far no luck.
--
Thanks,
Alexey Ermakov
> On Fri, Nov 01, 2019 at 03:15:33PM +0600, Alexey Ermakov wrote:
>
> I reproduced Sergei's test case on postgresql 11.5, replica hung up almost
> immediately after pgbench ran.
>
> 9907 - pid of startup process, 16387 - oid of test table, 2619 - oid of
> pg_statistic, 2840 - oid of toast table of pg_statistic.
>
> 1) pgbench on replica with 1 concurrent processes (-c 1):
>
> this case looks a bit different from what happened on initial report (which
> recently happened again btw) because at this time I can't even open new
> connection via psql or run query with pg_stat_activity - in hangs (pg_locks
> query works).
> perhaps because this time access exclusive lock is on pg_statistic table
> too, not only on it's toast table.
Interesting. I've tried the test case from previous email on the master
branch, and looks like I've got something similar with similar
stacktraces. After a short investigation, it looks pretty strange, a
backend 12682 is waiting on a lock, taken by 12584 (startup process):
[12682] LOG: process 12682 still waiting for AccessShareLock on relation 2619 of database 16384 after 1000.038 ms
[12682] DETAIL: Process holding the lock: 12584. Wait queue: 12689, 12674, 12671, 12682, 12683, 12677, 12680,
12676,12686, 12670, 12678, 12688, 12679, 12681, 12684, 12685, 12687.
[12682] STATEMENT: select * from tablename where i = 95;
And if I understand correctly, startup process is waiting inside
ResolveRecoveryConflictWithVirtualXIDs with a waitlist, containing
backendId = 14:
>>> p *waitlist
$3 = {
backendId = 14,
localTransactionId = 218
}
>>> p allProcs[pgprocnos]
...
lxid = 218,
pid = 12682,
pgprocno = 87,
backendId = 14,
databaseId = 16384,
...
So the same backend 12682, although I'm not sure yet why.
Alexey Ermakov <alexey.ermakov@dataegret.com> writes:
> On 9/23/19 01:06, Tom Lane wrote:
>> If you have a test case, could you collect stack traces from each
>> of the stuck processes? That would eliminate a lot of hypothesizing.
> I reproduced Sergei's test case on postgresql 11.5, replica hung up
> almost immediately after pgbench ran.
> stack trace of startup process 9907:
> #0 0x00007fdff4a025b3 in __select_nocancel () at
> ../sysdeps/unix/syscall-template.S:84
> #1 0x00005608fde0c6cd in pg_usleep (microsec=<optimized out>) at
> /build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/port/pgsleep.c:56
> #2 0x00005608fdc94126 in WaitExceedsMaxStandbyDelay () at
> /build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/storage/ipc/standby.c:201
> #3 ResolveRecoveryConflictWithVirtualXIDs (waitlist=0x5608fe46a450,
> reason=reason@entry=PROCSIG_RECOVERY_CONFLICT_SNAPSHOT) at
> /build/postgresql-11-d6c2wG/postgresql-11-11.5/build/../src/backend/storage/ipc/standby.c:262
This does not look like a deadlock: the startup process is just biding
its time until the standby delay timeout elapses, after which it's
gonna kill the conflicting queries.
It is, perhaps, arguable that it's a damn bad idea to allow
max_standby_streaming_delay or max_standby_archive_delay to be
set to "forever".
regards, tom lane
Re: BUG #16016: deadlock with startup process, AccessExclusiveLockon pg_statistic's toast table
От
Alexey Ermakov
Дата:
On 11/2/19 21:10, Tom Lane wrote: > This does not look like a deadlock: the startup process is just biding > its time until the standby delay timeout elapses, after which it's > gonna kill the conflicting queries. > > It is, perhaps, arguable that it's a damn bad idea to allow > max_standby_streaming_delay or max_standby_archive_delay to be > set to "forever". > > I agree, allowing max_standby_streaming_delay be set to -1 is perhaps not a good idea. there is although case when such setting could be used now, see "BUG #14044: Queries immediately conflict with recovery when recovery_min_apply_delay is used". [1] [1] https://postgr.es/m/20160324204550.2920.87946%40wrigleys.postgresql.org -- Alexey Ermakov