Horton

Re: hung backends stuck in spinlock heavy endless loop

Peter Geoghegan <pg@heroku.com>

View thread View on postgr.es
From: Peter Geoghegan <pg@heroku.com>
To: Andres Freund <andres@2ndquadrant.com>
Cc: Merlin Moncure <mmoncure@gmail.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2015-01-13T23:49:33Z
Lists: pgsql-hackers 
On Tue, Jan 13, 2015 at 3:21 PM, Andres Freund <andres@2ndquadrant.com> wrote:
> My guess is rather that it's contention on the freelist lock via
> StrategyGetBuffer's. I've seen profiles like this due to exactly that
> before - and it fits to parallel loading quite well.

I'm not saying you're wrong, but the breakdown of _bt_moveright()
relative to _bt_relandgetbuf() calls seems a bit fishy to me.

I don't remember seeing _bt_moveright()  or _bt_compare() figuring so
prominently, where _bt_binsrch() is nowhere to be seen. I can't see a
reference to _bt_binsrch() in either profile.

-- 
Peter Geoghegan

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.