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Date: Wed, 26 May 2010 15:11:00 +0200
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: pty infinite master control thread spawning problem
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Hi Dave,

On May 18 15:14, Dave Korn wrote:
> 
>     Hi,
> 
>   I'm having trouble with the latest changes to the pty control code.  In my
> case they manifest when I run parallel "make -j check" on GCC; after a minute
> or two all the expect processes end up spinning CPU and everything grinds to a
> halt.
> [...]
> - 32 threads all stuck in WFSO with no useful backtrace, and one that is
> frantically looping in cygthread::callfunc() at this point:
> >   if (issimplestub)
> >     {
> >       /* Wait for main thread to assign 'h' */
> >       while (!h)
> > 	yield ();
> 
> ... with "h" never getting set.
> 
>   The attached testcase demonstrates the underlying problem.

I applied a patch to CVS.  It worked for me, but while testing I
encountered a handle leak in your testcase and, naturally, I thought
it's my code.  After some tinkering it turned out that your parent
process neglects to wait for the child process.  Adding

  int status;
  waitpid (child_pid, &status, 0);

to the parent code removed the handle leak.  Please test the change in
Cygwin if it fixes the original problem for you.


Thanks for the report and, especially, the testcase,
Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat

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