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Message-ID: <4356BF11.1090101@scytek.de>
Date: Wed, 19 Oct 2005 17:48:01 -0400
From: Volker Quetschke <quetschke AT scytek DOT de>
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To: cygwin AT cygwin DOT com
Subject: Re: Hang with 20051018 (3rd version) snapshot while building OOo
References: <4356A25A DOT 4080204 AT scytek DOT de> <20051019205011 DOT GA22512 AT trixie DOT casa DOT cgf DOT cx>
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Christopher Faylor wrote:
> On Wed, Oct 19, 2005 at 03:45:30PM -0400, Volker Quetschke wrote:
> (snip)
>>Basically we still see the same problem as in
>><http://cygwin.com/ml/cygwin/2005-09/msg00803.html>.
>>
>>The build hangs in a tcsh like this:
>>(snip)
>>And by attaching strace to the hung pid and using "ls /proc/*/fd"
>>the attached (behind the cygcheck.log) strace was created.
> 
> Given the number of changes that have been made to cygwin, particularly
> in /proc handling, it's very difficult for me to believe that you are
> not seeing *any* differences in behavior and I'm wondering if you're
> actually seeing what you think you're seeing, i.e., I'm wondering if the
> process is just timing out and you are attributing it coming "unstuck"
> to the fact that you're doing "ls /proc/*/fd".  I can't see any reason
> why inspecting /proc should cause any kind of special behavior in the
> latest snapshots since /proc handling now occurs in its own thread.
I can completely understand your worries. My problem is that I cannot
reproduce the problem myself and all I can do is ask the people who
have this problem to try get some debug information.

I just asked for a confirmation that it really is the "ls /proc/*/fd"
that "unstucks" the process. I don't believe that "/usr/bin/tcsh -fc pwd"
needs a long time to finish so that we're getting a coincidence there.

Having said that, I never realized that before, maybe the problem really
lies in this special command. I mean due to some historic quirks every
makefile in the OOo tree has a line that sets a macro to the current path
using that command, but there are still lots of other commands (also executed
in a tcsh shell) in these makefiles that I never heard of to hang.
(I'll also verify that what I just said is really true, it's just an idea.)

> I could almost convince myself that there was a race in /proc handling
> before but I could never convince myself that doing something like "ls /proc/*/fd"
> would have any effect on it.  Nevertheless, I did make some changes to
> eliminate the potential source of hangs in this code.  So, I can't
> understand why you wouldn't see something different.

I have no clue either, especially as I also cannot reproduce and therefore
cannot pinpoint the problem. :(

Anyway, thanks for all your efforts!

   Volker

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