Re: hung backends stuck in spinlock heavy endless loop

Andres Freund <andres@2ndquadrant.com>

From: Andres Freund <andres@2ndquadrant.com>
To: Merlin Moncure <mmoncure@gmail.com>
Cc: Heikki Linnakangas <hlinnakangas@vmware.com>, Peter Geoghegan <pg@heroku.com>, Tom Lane <tgl@sss.pgh.pa.us>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2015-01-15T19:27:34Z
Lists: pgsql-hackers
On 2015-01-15 20:15:42 +0100, Andres Freund wrote:
> > WARNING:  did not find subXID 14955 in MyProc
> > CONTEXT:  PL/pgSQL function cdsreconcileruntable(bigint) line 35
> > during exception cleanup
> > WARNING:  you don't own a lock of type RowExclusiveLock
> > CONTEXT:  PL/pgSQL function cdsreconcileruntable(bigint) line 35
> > during exception cleanup
> > LOG:  could not send data to client: Broken pipe
> > CONTEXT:  PL/pgSQL function cdsreconcileruntable(bigint) line 35
> > during exception cleanup
> > STATEMENT:  SELECT CDSReconcileRunTable(2151)
> > WARNING:  ReleaseLockIfHeld: failed??
> > CONTEXT:  PL/pgSQL function cdsreconcileruntable(bigint) line 35
> > during exception cleanup
> > ERROR:  failed to re-find shared proclock object
> > CONTEXT:  PL/pgSQL function cdsreconcileruntable(bigint) line 35
> > during exception cleanup
> > STATEMENT:  SELECT CDSReconcileRunTable(2151)
> > WARNING:  AbortSubTransaction while in ABORT state
> > WARNING:  did not find subXID 14955 in MyProc
> > WARNING:  you don't own a lock of type AccessShareLock
> > WARNING:  ReleaseLockIfHeld: failed??
> > ERROR:  failed to re-find shared proclock object
> > WARNING:  AbortSubTransaction while in ABORT state
> > WARNING:  did not find subXID 14955 in MyProc
> > WARNING:  you don't own a lock of type AccessShareLock
> > WARNING:  ReleaseLockIfHeld: failed??
> > WARNING:  you don't own a lock of type ShareLock
> > TRAP: FailedAssertion("!(FastPathStrongRelationLocks->count[fasthashcode]
> > > 0)", File: "lock.c", Line: 1240)
> > LOG:  server process (PID 10117) was terminated by signal 6: Aborted
> > LOG:  terminating any other active server processes
> 
> Ick.
> 
> Were there any 'LOG: Handling deadlock detected on CdsRunTableId' log
> entries before? It's hard to know from here, but the 'during exception
> cleanup' indicates a problem in abort handling.  Were there any deadlock
> detected errors closeby?

Alternatively were there any 'LOG: CdsRunTableId %s Failed' messages? If
so, what was the cause?

> You're catching deadlock errors in a subtransaction. Hm.

A couple questions:
* Do you also use lock_timeout/statement_timeout? If so, what are their
  settings + deadlock_timeout?
* were any processes killed at that time?

Greetings,

Andres Freund

-- 
 Andres Freund	                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services


Commits

  1. Improve hash_create's API for selecting simple-binary-key hash functions.

  2. Fix WAL-logging of B-tree "unlink halfdead page" operation.

  3. Fix backup-block numbering in redo of b-tree split.

  4. Cleanup of new b-tree page deletion code.

  5. Fix bug in the new B-tree incomplete-split code.

  6. Fix bug in new B-tree page deletion code.

  7. Fix rm_desc routine of b-tree page delete records.

  8. Make the handling of interrupted B-tree page splits more robust.

  9. Fix race condition in B-tree page deletion.