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Date: Thu, 17 Jul 2025 17:19:49 +0200
To: cygwin AT cygwin DOT com
Subject: Re: Calling system() in multi-threads.
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From: Corinna Vinschen via Cygwin <cygwin AT cygwin DOT com>
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On Jul 17 23:14, Takashi Yano via Cygwin wrote:
> Hi Corinna,
> 
> On Wed, 16 Jul 2025 17:36:42 +0200
> Corinna Vinschen wrote:
> > On Jul 16 23:52, Takashi Yano via Cygwin wrote:
> > > Do you have any idea?
> > 
> > Locking would be super-simple.
> > 
> > But theoretically it should be possible to use a local child_info_spawn
> > variable at this point.  The ch_spawn child_info_spawn instance is not
> > copied to the child anyway, so that should be safe.  The same goes for
> > posix_spawn() then, btw.
> > 
> > I checked the sources and I don't see any dependency to ch_spawn
> > from a spawning process, in contrast to an exec'ing process.  That
> > doesn't mean there is none, just that I didn't find any.
> 
> Thanks!
> As a starting point, I tried tntroducing locking. It almost works
> as expected, however, sometimes my STC in my first report is hangs
> if N is large e.g. 100. The patch is as attached.
> 
> What am I missing?

I don't know.  You're perhaps not releasing the lock in all cases.
But I would have to debug this just like you ¯\_(ツ)_/¯

Out of curiosity, did you try using a locale child_info_spawn instance
instead?  That would be a rather nice solution, but I'm pretty sure
there's some other problem lurking in the dark...


Corinna

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