From: Corinna Vinschen <corinna-cygwin@cygwin.com>
To: cygwin@cygwin.com
Subject: Re: pthread_kill: signals remain pending after target thread exits
Date: Fri, 23 Oct 2015 14:30:00 -0000 [thread overview]
Message-ID: <20151023125540.GI5319@calimero.vinschen.de> (raw)
In-Reply-To: <28F5B565B6F6424C87E4AC0DCC84316575D73A86@S1P5DAG5C.EXCHPROD.USA.NET>
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On Oct 22 02:08, John Carey wrote:
> > From: Corinna Vinschen [corinna-cygwin@cygwin.com]
> > Sent: Wednesday, October 21, 2015 4:48 AM
> > Subject: Re: pthread_kill: signals remain pending after target thread exits
> ...
> > > On Sep 11 18:11, John Carey wrote:
> > > There seems to be a problem with pthread_kill: a pending signal
> > > targeting a particular thread prevents other threads from receiving
> > > signals sharing the same signal number--even after the original target
> > > thread exits and is joined.
> ...
> > The important thing here is to get rid of the pending signal.
>
> Yes, I agree that is the most important thing.
>
> > > In my view it would be desirable if:
> > >
> > > - Pending signals targeting a particular thread would not outlast
> > > that thread.
> >
> > Since you looked into the code anyway, do you have an idea how to
> > implement that? For a start, do you have a simple testcase, only
> > the bare code needed to reproduce the issue?
>
> I've attached a test case that I *think* gets into the right spot, at
> least for 64-bit Cygwin 2.0.4. That is, it hangs trying to receive
> the signal, instead of terminating. (This test passes (terminates) in
> 32-bit Cygwin 1.7.9 and 64-bit Ubuntu 14.04.3 LTS.)
Thanks for the testcase. I applied a patch which hopefully works as
desired, at least to fix the immediate problem of the remaining pending
signal when a thread exits. I uploaded a new developer snapshot to
https://cygwin.com/snapshots. Please give it a try.
Note that the today's snapshot does *NOT* contain the changes concerning
the new ACL handling, so people testing that stuff should skip this
snapshot.
> > > - Multiple pending signals targeting different threads could
> > > coexist, even if they shared the same signal number. This happens
> > > on Linux (Ubuntu 14.04.3), where I can generate two signals for two
> > > different threads, then sleep for a bit in each target thread, and
> > > finally have each thread receive its signal with sigwait()--neither
> > > signal is lost during the sleeping period.
> >
> > That requires to extend the handling for pending signals. That's
> > a rather bigger task...
>
> Yeah. It's nice if threads don't interfere with each other, but this
> part would indeed be harder to change.
I added that to my neverending TODO list. Maybe I get around to it at
one point.
Thanks,
Corinna
--
Corinna Vinschen Please, send mails regarding Cygwin to
Cygwin Maintainer cygwin AT cygwin DOT com
Red Hat
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next prev parent reply other threads:[~2015-10-23 12:55 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-11 18:11 John Carey
2015-10-21 11:48 ` Corinna Vinschen
2015-10-22 8:34 ` John Carey
2015-10-23 14:30 ` Corinna Vinschen [this message]
2015-10-27 11:15 ` Corinna Vinschen
2015-10-28 3:39 ` John Carey
2015-10-28 13:28 ` Corinna Vinschen
2015-10-29 13:23 ` Corinna Vinschen
2015-10-29 17:34 ` John Carey
2015-10-29 17:40 ` John Carey
2015-11-02 14:18 ` Corinna Vinschen
2015-11-02 17:58 ` Corinna Vinschen
2015-11-02 23:55 ` John Carey
2015-11-03 9:00 ` Corinna Vinschen
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