Re: SSI patch version 14

From: Dan Ports <drkp(at)csail(dot)mit(dot)edu>
To: Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>
Cc: Simon Riggs <simon(at)2ndQuadrant(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: SSI patch version 14
Date: 2011-01-26 20:16:23
Message-ID: 20110126201623.GA57071@csail.mit.edu
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On Wed, Jan 26, 2011 at 10:01:28AM -0600, Kevin Grittner wrote:
> In looking at it just now, I noticed that after trying it in a
> couple different places what was left in the repository was not the
> optimal version for code coverage. I've put this back to the
> version which did a better job, for reasons described in the commit
> comment:

Isn't this placement the same as the version we had before that didn't
work?

Specifically, aren't we going to have problems running with
TEST_OLDSERXID enabled because CreatePredTran succeeds and links a new
SerializableXact into the active list, but we don't initialize it
before we drop SerializableXactHashLock to call
SummarizeOldestCommittedSxact?

I seem to recall SummarizeOldestCommittedSxact failing before because
of the uninitialized entry, but more generally since we drop the lock
something else might scan the list.

(This isn't a problem in the non-test case because we'd only do that if
CreatePredTran fails.)

Dan

--
Dan R. K. Ports MIT CSAIL http://drkp.net/

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