Re: [Libevent-users] deadlock in libevent-2.0.5-beta

[Nick Mathewson <nickm@xxxxxxxxxxxxx>]

On Sun, Jul 4, 2010 at 4:29 AM, Avi Bab <avib@xxxxxxxxxx> wrote:
>
> Indeed it seems that someone, some when, failed to release the lock.
> At the time of the deadlock the third thread (The ReceiverThread) is dispatching on a different eventbase.
>
> This third thread does do some manipulation on bufferevents that are registered with the Sender's event_base:

 [..]
>
> This is the only interaction with the third thread.
> I do not see a relation to the deadlock.
>

Confusing!  I don't see how this would cause the deadlock either.

Have you tried configuring the lock debugging feature?  Just after you
call evthread_use_pthreads(), call evthread_enable_lock_debugging():
it will put wrappers around all the locks and locking callbacks to
track each lock's current owner and recursion count.  If there are
gross errors, you'll get an assertion failure with a hopefully useful
stack trace.  If not,  you can inspect the recursion count and owner
in the debugger by casting the lock to "struct debug_lock" and looking
at the  count and held_by variables.  [The owner is just a pthread_t
as an unsigned long, as returned by pthread_self().]

yrs,
-- 
Nick
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