Horton

Re: hung backends stuck in spinlock heavy endless loop

Merlin Moncure <mmoncure@gmail.com>

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From: Merlin Moncure <mmoncure@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Peter Geoghegan <pg@heroku.com>, Andres Freund <andres@2ndquadrant.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2015-01-14T15:08:04Z
Lists: pgsql-hackers 
On Wed, Jan 14, 2015 at 9:05 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Merlin Moncure <mmoncure@gmail.com> writes:
>> On Wed, Jan 14, 2015 at 8:41 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>>> What are the autovac processes doing (according to pg_stat_activity)?
>
>> pid,running,waiting,query
>> 7105,00:28:40.789221,f,autovacuum: VACUUM ANALYZE pg_catalog.pg_class
>
> Hah, I suspected as much.  Is that the one that's stuck in
> LockBufferForCleanup, or the other one that's got a similar
> backtrace to all the user processes?

Yes, it is pg_class is coming from  LockBufferForCleanup ().  As you
can see above, it has a shorter runtime.   So it was killed off once
about a half hour ago which did not free up the logjam.  However, AV
spawned it again and now it does not respond to cancel.

merlin

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.