Date: Tue, 27 Aug 2013 17:55:56 +0200
From: Andres Freund <andres@2ndquadrant.com>
To: Merlin Moncure <mmoncure@gmail.com>
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 <degtyaryov@gmail.com>,
 postgres performance list <pgsql-performance@postgresql.org>
Subject: Re: Cpu usage 100% on slave. s_lock problem.
Message-ID: <20130827155556.GA9061@awork2.anarazel.de>
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On 2013-08-27 09:57:38 -0500, Merlin Moncure wrote:
> + bool
> + RecoveryMightBeInProgress(void)
> + {
> + 	/*
> + 	 * We check shared state each time only until we leave recovery mode. We
> + 	 * can't re-enter recovery, so there's no need to keep checking after the
> + 	 * shared variable has once been seen false.
> + 	 */
> + 	if (!LocalRecoveryInProgress)
> + 		return false;
> + 	else
> + 	{
> + 		/* use volatile pointer to prevent code rearrangement */
> + 		volatile XLogCtlData *xlogctl = XLogCtl;
> + 
> + 		/* Intentionally query xlogctl without spinlocking! */
> + 		LocalRecoveryInProgress = xlogctl->SharedRecoveryInProgress;
> + 
> + 		return LocalRecoveryInProgress;
> + 	}
> + }

I don't think it's acceptable to *set* LocalRecoveryInProgress
here. That should only be done in the normal routine.

Greetings,

Andres Freund

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


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