From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | Merlin Moncure <mmoncure(at)gmail(dot)com> |
Cc: | Peter Geoghegan <pg(at)heroku(dot)com>, Andres Freund <andres(at)2ndquadrant(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: hung backends stuck in spinlock heavy endless loop |
Date: | 2015-01-14 00:05:10 |
Message-ID: | 31250.1421193910@sss.pgh.pa.us |
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Lists: | pgsql-hackers |
Merlin Moncure <mmoncure(at)gmail(dot)com> writes:
> On Tue, Jan 13, 2015 at 5:54 PM, Peter Geoghegan <pg(at)heroku(dot)com> wrote:
>> In case it isn't clear, I think that the proximate cause here may well
>> be either one (or both) of commits
>> efada2b8e920adfdf7418862e939925d2acd1b89 and/or
>> 40dae7ec537c5619fc93ad602c62f37be786d161. Probably the latter. I think
>> that the profile is roughly consistent with that, although I may well
>> be wrong.
> I'm out of time for the day, but I'm fairly confident I can reproduce.
> I'll see if I can reverse those commits tomorrow and retest (I'm on
> development box).
I'm not convinced that Peter is barking up the right tree. I'm noticing
that the profiles seem rather skewed towards parser/planner work; so I
suspect the contention is probably on access to system catalogs. No
idea exactly why though.
It would be good to collect a few stack traces from the hung backends,
rather than relying on perf statistics.
regards, tom lane
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