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Re: Is mutex ownership handed off strictly only to threads which have requested for the lock prior to unlocking?

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On 2016-08-31, Sibin Thomas <sibinpthomas@gmail.com> wrote:
> I was influenced by the discussion here - http://austingroupbugs.net/view.php?id=609
> I thought similar to pthread_signal() pthread_mutex_unlock() too does an "atomic unblock" of threads already in its 'Wait queue'

pthread_cond_{signal,broadcast} do not do any atomic unblock,
and can be invoked without the mutex being held.

The atomicity is in the pthread_cond_{wait,timedwait} operations. From
the application point of view, it appears that transition of from
"mutex owner" to "waiting on condition" is atomic. There is no
in-between window of time during which the signal or broadcast
could take place such that a thread is neither mutex owner,
nor waiting on the condition.

The signal/broadcast itself though is basically just a best effort:
whatever thread or threads, are actually waiting at the moment of the
call are woken up, and that's it.

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Thread

Is mutex ownership handed off strictly only to threads which have requested for the lock prior to unlocking? Sibin Thomas <sibinpthomas@gmail.com> - 2016-08-30 22:39 -0700
  Re: Is mutex ownership handed off strictly only to threads which have requested for the lock prior to unlocking? Casper H.S. Dik <Casper.Dik@OrSPaMcle.COM> - 2016-08-31 08:24 +0000
    Re: Is mutex ownership handed off strictly only to threads which have requested for the lock prior to unlocking? Sibin Thomas <sibinpthomas@gmail.com> - 2016-08-31 04:08 -0700
      Re: Is mutex ownership handed off strictly only to threads which have requested for the lock prior to unlocking? Casper H.S. Dik <Casper.Dik@OrSPaMcle.COM> - 2016-08-31 11:41 +0000
        Re: Is mutex ownership handed off strictly only to threads which have requested for the lock prior to unlocking? Sibin Thomas <sibinpthomas@gmail.com> - 2016-08-31 10:08 -0700
      Re: Is mutex ownership handed off strictly only to threads which have requested for the lock prior to unlocking? Kaz Kylheku <221-501-9011@kylheku.com> - 2016-08-31 18:08 +0000
        Re: Is mutex ownership handed off strictly only to threads which have requested for the lock prior to unlocking? Sibin Thomas <sibinpthomas@gmail.com> - 2016-09-01 03:50 -0700
  Re: Is mutex ownership handed off strictly only to threads which have requested for the lock prior to unlocking? Kaz Kylheku <221-501-9011@kylheku.com> - 2016-08-31 17:59 +0000

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