Re: [PERFORM] Hanging queries on dual CPU windows

From: "Qingqing Zhou" <zhouqq(at)cs(dot)toronto(dot)edu>
To: pgsql-hackers(at)postgresql(dot)org
Subject: Re: [PERFORM] Hanging queries on dual CPU windows
Date: 2006-03-13 05:38:58
Message-ID: dv30nr$1aaf$1@news.hub.org
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""Magnus Hagander"" <mha(at)sollentuna(dot)net> wrote
> Ok, I've coded up a patch that changes the code to use a mutex instead.

Are we asserting the problem is caused by the spinlock random wake-up order?
I am not sure why this would fix the problem. If my memory serves, a
critical section might be a problem if one process aborts unexpected while
it is inside. Other waiting processes can never have a chance to enter it
(also have no chance to handle SIGQUIT) -- so this patch may solve this.

There is another suspect in http://www.devisser-siderius.com/stack1.jpg,
i.e., process 3 does shmctl. I once filed a server core dump bug in win32 of
reporting WSAEWOULDBLOCK.
(http://archives.postgresql.org/pgsql-bugs/2006-02/msg00185.php) AFAICS, it
is actually an mistranslated EINTR. There seems some relation between these
issues, but I didn't come up with a complete theory of it.

Regards,
Qingqing

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