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From: litter AT null DOT net
Subject: Re: Cygwin bash for loops : repeated errors : [main] bash 1972 fork: child -1 - CreateProcessW failed for <bash.exe> errno 9 bash: fork: Bad file descriptor
Message-ID: <560BC46C.7050308@null.net>
Date: Wed, 30 Sep 2015 13:15:56 +0200
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>>>>> It seems a race problem, due to the repetitive fork of grep
>>>>> for every line of some-file
>>>>
>>>> So why does it fail? Seems like a bug to me!
>>>>
>>>> Regards,
>>>> Paul
>>>
>>> As does not fail on my computer, I suspect is a race between your AV and
>>> cygwin and sometimes cygwin wins.
>>>
>>>
>>> Regards
>>> Marco.
>>
>> Good for you. I don't have AV SW as I mentioned. And even so, that still makes it a bug.
> 
> Your system timing performance as so poor that something
> is likely interfering.
> Don't assume that is a cygwin bug.
> 
>> Anyhow, a suspicion is speculative. I thought this mailing list was meant to report issues, and I think this is an issue.
> 
> Yes, this is the right place.
> 
>> How can I further diagnose this? Is there a known way to further determine what's causing this?
> 
> start with
>  > Problem reports:       http://cygwin.com/problems.html
> 
> "Run cygcheck -s -v -r > cygcheck.out and include that file as an 
> attachment in your report. Please do not compress or otherwise encode 
> the output. Just attach it as a straight text file so that it can be 
> easily viewed. "
> 
> so we can look at your system configuration.
> 
>> Regards,
>> Paul
> 
> Marco


After observing for a week on the system with the fix applied, I did not see this issue reoccur.
I do however still suspect that it is a bug in cygwin, indeed a race condition of some sorts, which probably becomes apparent when starting up a process takes (much) longer than expected.
As said, the guard32.dll is probably scanning the new CreateProcess candidate. I suspect that there's an timing assumption in the Cygwin fork code. But as I cannot be sure, I leave it at that.

Regards,
Paul

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