From: Jan de Visser <jdevisser@digitalfairway.com>
To: pgsql-performance@postgresql.org
Subject: Re: Hanging queries on dual CPU windows
Date: Fri, 10 Mar 2006 09:03:14 -0500
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On Friday 10 March 2006 04:20, Magnus Hagander wrote:
> > > Is it possible to get a stack trace from the stuck process?
> >
> > =A0I dunno
> >
> > > if you've got anything gdb-equivalent under Windows, but that's the
> > > first thing I'd be interested in ...
> >
> > Here ya go:
> >
> > http://www.devisser-siderius.com/stack1.jpg
> > http://www.devisser-siderius.com/stack2.jpg
> > http://www.devisser-siderius.com/stack3.jpg
> >
> > There are three threads in the process. I guess thread 1
> > (stack1.jpg) is the most interesting.
> >
> > I also noted that cranking up concurrency in my app
> > reproduces the problem in about 4 minutes ;-)
>

Just reproduced again.=20

> Actually, stack2 looks very interesting. Does it "stay stuck" in
> pg_queue_signal? That's really not supposed to happen.

Yes it does.=20

>
> Also, can you confirm that stack1 actually *stops* in
> pgwin32_waitforsinglesocket? Or does it go out and come back? ;-)
>
> (A good signal of this is to check the cswitch delta. If it stays at zero,
> then it's stuck. If it shows any values, that means it's actuall going out
> and coming back)

I only see CSwitch change once I click OK on the thread window. Once I do=20
that, it goes up to 3 and back to blank again. The 'context switches' count=
er=20
does not increase like it does for other processes (like e.g. process=20
explorer itself).

Another thing which may or may not be of interest: Nothing is listed in the=
=20
'TCP/IP' tab for the stuck process. I would have expected to see at least t=
he=20
socket of the client connection there??

>
> And finally, is this 8.0 or 8.1? There have been some significant changes
> in the handling of the signals between the two...

This is 8.1.3 on Windows 2003 Server. Also reproduced on 8.1.0 and 8.1.1 (a=
lso=20
on 2K3).=20

>
> //Magnus

jan

=2D-=20
=2D-------------------------------------------------------------
Jan de Visser =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 jdevisser@digitalfair=
way.com

=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 Baruk Khazad! Khazad ai-menu!
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