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Re: slru.c race condition (was Re: TRAP: FailedAssertion("!((itemid)->lp_flags

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com>,Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>,Gavin Sherry <swm(at)linuxworld(dot)com(dot)au>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: slru.c race condition (was Re: TRAP: FailedAssertion("!((itemid)->lp_flags
Date: 2005-10-31 18:17:05
Message-ID: 200510311817.j9VIH5Y12628@candle.pha.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-patches
Tom Lane wrote:
> "Jim C. Nasby" <jnasby(at)pervasive(dot)com> writes:
> > On Sun, Oct 30, 2005 at 06:17:53PM -0500, Tom Lane wrote:
> >> This won't do as a permanent patch, because it isn't guaranteed to fix
> >> the problem on machines that don't strongly order writes, but it should
> >> work on Opterons, at least well enough to confirm the diagnosis.
> 
> > Given your proposed fix on -patches, do you still need me to test this?
> 
> Yes; we still need to verify that my theory actually explains your
> problem.  Given that I'm positing that you can repeatedly hit a
> two-instruction window, this is by no means a sure thing.  We need
> it tested (and with asserts on, so that we can tell if it's fixed
> the problem or not).
> 
> > Also, is there any heap corruption risk associated with this patch?
> 
> Look, Jim, I'm trying to help you fix this.  Are you going to help or not?
> If you want some kind of written guarantee, you're not going to get one.

I think we can say Jim gets his money back if he finds a bug.  :-)

-- 
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman(at)candle(dot)pha(dot)pa(dot)us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

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