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Re: Freeze in perl script after cygwin upgrade 1.5.17 -> 1.5.18


After upgrading cygwin yesterday I get the following reproducible hang
in a perl script starting an external program.

This is the perl script that works with the 1.5.17 cygwin dll and hangs
with 1.5.18:

Did you also see this with snapshots?
I didn't try. I will first try to condense the problem to a simpler testcase.
If that fails I can do a binary search backward.

While waiting for the answer to the above rhetorical question, I thought
I'd add an observation: Rather than go to a lot of effort running things
and getting straces which may or may not illustrate the problem, it is
ALWAYS a much better plan to reduce things to a simple test case which
can be reproduced by people who may or may not use strace to debug the
problem.
I know. I reduced the 10h build of OpenOffice.org to the 5 lines of perl
script that fails. I didn't expect an immediate solution for the problem,
but I attached the end of the strace anyway in the hope that it might
trigger an idea for someone.

The division of labor should be like this:

The reporter more or less understands the code for which they are
reporting problems so they should be able to reduce things, as much as
possible, to a test case which reproduces the problem.  With a test case
in hand, you can then hand off the problem to someone who understands
cygwin and who will be able to use the simple test case to debug the
problem.
Fair enough.

Attempting to bypass the test case step and do the cygwin maintainer's
"job" of generating strace output is not as likely to be a worthwhile
endeavor as producing the test case itself.  You are not likely to jump
start the debugging process by doing this.  Even if the strace output
was useful, the debugger would have no real way of knowing if they fixed
the problem without a test case.
Well, I could have waited reporting this problem until I have extracted
a 2 line testcase, but I wanted to post what I have so far.

The theory here is that a bug reporter shouldn't need to spend any time
trying to debug cygwin (via strace) unless they really are interested in
learning about cygwin internals.  That means that the most profitable
thing a bug reporter can do is create a test case.
Quote from the original mail:
> * Attention! Stop reading if you're offended by unsolicited strace outputs. *

Stop wasting your precious time complaining about my useless strace. I didn't
waste much time producing it and it shows that perl is waiting for
something, not more.

Regards

Volker

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