Re: FATAL: semctl(1672698088, 12, SETVAL, 0) failed

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Qingqing Zhou <zhouqq(at)cs(dot)toronto(dot)edu>
Cc: pgsql-bugs(at)postgresql(dot)org
Subject: Re: FATAL: semctl(1672698088, 12, SETVAL, 0) failed
Date: 2006-03-01 03:08:37
Message-ID: 200603010308.k2138bO09022@candle.pha.pa.us
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Qingqing Zhou wrote:
>
> "Bruce Momjian" <pgman(at)candle(dot)pha(dot)pa(dot)us> wrote
> > > In port/win32.h, we have
> > >
> > > #undef EAGAIN
> > > #undef EINTR
> > > #define EINTR WSAEINTR
> > > #define EAGAIN WSAEWOULDBLOCK
> > >
> > > What's the rationale of doing so?
> >
> > We did this so that our code could refer to EINTR/EAGAIN without
> > port-specific tests.
> >
>
> AFAICS, by doing so, the EINTR/EAGAIN will be translated into
> WSAINTR/WSAEWOULDBLOCK through *all* the backend code. That's seems not
> appropriate for the code not involving any socket stuff ... I think we need
> a fix here.

Uh, how do we handle it now? I thought we did just that.

> http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dllproc/base/waitformultipleobjectsex.asp
> >
> > and it isn't clear what return failure values it has. We certainly
> > could loop on WSAEINTR. Can you test it?
> >
>
> Yeah, looking at other code of using semop(), we could plug in a loop in the
> win32 semctl():
>
> /* Quickly lock/unlock the semaphore (if we can) */
> + do
> + {
> + errStatus = semop(semId, &sops, 1);
> + } while (errStatus < 0 && errno == EINTR);
>
> if (semop(semId, &sops, 1) < 0)
> return -1;
>
> But:
> (1) The EINTR problem happens rather rare, so testing it is difficult;
> (2) I would rather not doing the above changes before we understand what's
> happened here, especially when we have seen a EAGAIN reported here.

OK, so how do we find the answer?

--
Bruce Momjian http://candle.pha.pa.us
SRA OSS, Inc. http://www.sraoss.com

+ If your life is a hard drive, Christ can be your backup. +

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