Re: [HACKERS] lock AccessShareLock on object 0/1260/0 is already held
Hello
2013/1/4 Pavel Stehule pavel.steh...@gmail.com:
2013/1/4 Tom Lane t...@sss.pgh.pa.us:
Pavel Stehule pavel.steh...@gmail.com writes:
What is state of this issue?
http://archives.postgresql.org/pgsql-hackers/2011-09/msg00423.php
AFAICS we never identified the cause. It was pretty clear that
something was failing to clean up shared-memory lock data structures,
but not what that something was. The last productive suggestion was
to add process-exit-time logging of whether unreleased locks remain,
but if Dave ever did that, he didn't report back what he found.
probably I am able to find statement, that was canceled as last
success statement from our application logs. And probably it will be
LOCK ... or CREATE TABLE AS SELECT
Recheck on session end can help us to drop this leaked locks, but I
don't understand how it can help with finding with finding the cause?
I am sending a patch that removes a described issue
we use this patch on our productions servers with some others diagnostics
+* GOODDATA
+*
+* we would to diagnose how much often is proces startup find
+* orphaned PGPROCLOCKS. Don't use ereport, because process is
+* not fully prepared in this moment.
+*/
+ {
+ int i;
+ boolfix_orphaned_locks = false;
+
+ for (i = 0; i NUM_LOCK_PARTITIONS; i++)
+ {
+ if (!SHMQueueEmpty((MyProc-myProcLocks[i])))
+ {
+ fprintf(stderr, ProcKill: found orphaned
PGPROCLOCK proc:%p,
pid:%d\n, MyProc, MyProcPid);
+ fix_orphaned_locks = true;
+ break;
+ }
+ }
+
+ if (fix_orphaned_locks)
+ {
+ LockReleaseAll(DEFAULT_LOCKMETHOD, true);
+ /* Release transaction-level advisory locks */
+ LockReleaseAll(USER_LOCKMETHOD, false);
+ fix_orphaned_locks = false;
+
+ for (i = 0; i NUM_LOCK_PARTITIONS; i++)
+ {
+ if (!SHMQueueEmpty((MyProc-myProcLocks[i])))
+ {
+ fprintf(stderr, ProcKill: found
orphaned PGPROCLOCK proc:%p,
pid:%d again\n, MyProc, MyProcPid);
+ fix_orphaned_locks = true;
+ break;
+ }
+ }
+
+ if (fix_orphaned_locks)
+ fprintf(stderr, ProcKill: orphaned PGPROCLOCK
proc:%p, pid:%d
was removed\n, MyProc, MyProcPid);
+ else
+ fprintf(stderr, ProcKill: orphaned PGPROCLOCK
proc:%p, pid:%d
was not removed\n, MyProc, MyProcPid);
+ }
+ }
+
but it dosn't detect and removed any orphaned locks, so this code is
not necessary.
I can't to explain why moving initialization from proces to global
helps, but it just helps.
9.1 will be suppported next four years so maybe this patch can be
usefull for somebody or maybe can be merged
Regards
Pavel
Maybe you could add such logging on your machines.
regards, tom lane
orphaned-locks-simple.patch
Description: Binary data
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[HACKERS] lock AccessShareLock on object 0/1260/0 is already held
Hello
What is state of this issue?
http://archives.postgresql.org/pgsql-hackers/2011-09/msg00423.php
We detect this issue in our servers - we use 9.1.6 on Linux
locktype | database | relation | page | tuple | virtualxid |
transactionid | classid | objid | objsubid | virtualtransaction | pid
| mode | granted
--+--+--+--+---++---+-+---+--++---+-+-
relation | 5630403 | 1259 | | ||
| | | | 20/0 | 14960 |
AccessShareLock | t
Interesting of this issue - it is blocks DBI login
Exception thrown: DBI
connect('database=xxx;host=yyy;port=5432','username',...) failed:
FATAL: lock AccessShareLock on object 5630403/1259/0 is already
held#012
but I am able to login to this database from command line without problems
There is unfriendly error message - I cannot get information about
statement that exactly raise this fatal state.
The most old message that I found is
Dec 10 15:01:51 cl-pdwh-d01 postgres[32548]: [6-1] (2012-12-10
15:01:51 CET db_hw7ny3roi257xe886fvc5krqgosp6g23)
Dec 10 15:01:51 cl-pdwh-d01 postgres[32548]: [6-2] ERROR: canceling
statement due to user request
Dec 10 15:01:51 cl-pdwh-d01 postgres[32738]: [6-1] (2012-12-10
15:01:51 CET db_hw7ny3roi257xe886fvc5krqgosp6g23)
Dec 10 15:01:51 cl-pdwh-d01 postgres[32738]: [6-2] FATAL: lock
AccessShareLock on object 5630403/1259/0 is already held
Dec 10 15:01:51 cl-pdwh-d01 postgres[32739]: [6-1] (2012-12-10
15:01:51 CET db_hw7ny3roi257xe886fvc5krqgosp6g23)
Dec 10 15:01:51 cl-pdwh-d01 postgres[32739]: [6-2] FATAL: lock
AccessShareLock on object 5630403/1259/0 is already held
Dec 10 15:02:29 cl-pdwh-d01 postgres[957]: [6-1] (2012-12-10 15:02:29
CET db_hw7ny3roi257xe886fvc5krqgosp6g23)
Dec 10 15:02:29 cl-pdwh-d01 postgres[957]: [6-2] FATAL: lock
AccessShareLock on object 5630403/1259/0 is already held
Regards
Pavel Stehule
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Re: [HACKERS] lock AccessShareLock on object 0/1260/0 is already held
Pavel Stehule pavel.steh...@gmail.com writes: What is state of this issue? http://archives.postgresql.org/pgsql-hackers/2011-09/msg00423.php AFAICS we never identified the cause. It was pretty clear that something was failing to clean up shared-memory lock data structures, but not what that something was. The last productive suggestion was to add process-exit-time logging of whether unreleased locks remain, but if Dave ever did that, he didn't report back what he found. Maybe you could add such logging on your machines. regards, tom lane -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] lock AccessShareLock on object 0/1260/0 is already held
2013/1/4 Tom Lane t...@sss.pgh.pa.us: Pavel Stehule pavel.steh...@gmail.com writes: What is state of this issue? http://archives.postgresql.org/pgsql-hackers/2011-09/msg00423.php AFAICS we never identified the cause. It was pretty clear that something was failing to clean up shared-memory lock data structures, but not what that something was. The last productive suggestion was to add process-exit-time logging of whether unreleased locks remain, but if Dave ever did that, he didn't report back what he found. probably I am able to find statement, that was canceled as last success statement from our application logs. And probably it will be LOCK ... or CREATE TABLE AS SELECT Recheck on session end can help us to drop this leaked locks, but I don't understand how it can help with finding with finding the cause? Maybe you could add such logging on your machines. regards, tom lane -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
