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From: Ken Brown <kbrown@cornell.edu>
To: "cygwin@cygwin.com" <cygwin@cygwin.com>
Subject: Re: timerfd deadlock
Date: Mon, 24 Jun 2019 20:16:00 -0000	[thread overview]
Message-ID: <c4d32d35-a668-bca9-f783-bc5ee09ba4ff@cornell.edu> (raw)
In-Reply-To: <20190611085221.GC3520@calimero.vinschen.de>

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On 6/11/2019 4:52 AM, Corinna Vinschen wrote:
> On Jun  7 12:10, Ken Brown wrote:
>> While testing some new pipe code, I'm occasionally seeing a timerfd deadlock:
>> The main thread is stuck in timerfd_tracker::dtor at timerfd.cc:354, waiting for
>> the timerfd thread to close; and the timerfd thread is stuck at timerfd.cc:140,
>> waiting to acquire a mutex that's held by timerfd_tracker::dtor.
> 
> Hmm, I had hoped my current code does not have a deadlock situation
> anymore, but I was wrong, apparently.
> 
> Is there any chance to create an STC?

I haven't been able to create an STC.  The deadlock seems to depend on a rare 
timing fluke, and I've only seen it when running a parallel make on a clean 
emacs tree, with my new pipe code installed.

On the other hand, I think I have a simple fix, which I'll send to 
cygwin-patches.  With this patch, I ran the parallel make 15 times without 
getting the deadlock.  After reverting the patch, I got the deadlock on the 4th run.

Ken
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      parent reply	other threads:[~2019-06-24 20:16 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-07 12:10 Ken Brown
2019-06-11  8:52 ` Corinna Vinschen
2019-06-11 13:18   ` Ken Brown
2019-06-24 20:16   ` Ken Brown [this message]

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