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Re: [Libevent-users] Signals and priority queues



Well, after playing around a bit, I did finally manage to recreate the scenario in my main program using your example. The attached program reliably crashes with the following output and backtrace:

Ralph:system rhc$ ./evpri-test
Libevent 2.0.13-stable-openmpi
SIGNAL EVENT DEFINED
FIRST TERMINATION EVENT DEFINED
CAUGHT FIRST TERMINATION EVENT
SECOND TERMINATION EVENT DEFINED
Segmentation fault (core dumped)


#0  0x0000000100151ab4 in event_queue_remove (base=0x1003000a0, ev=0x7fff5fbff040, queue=8) at event.c:2499
2499			TAILQ_REMOVE(&base->activequeues[ev->ev_pri],
(gdb) where
#0  0x0000000100151ab4 in event_queue_remove (base=0x1003000a0, ev=0x7fff5fbff040, queue=8) at event.c:2499
#1  0x0000000100150d88 in event_del_internal (ev=0x7fff5fbff040) at event.c:2216
#2  0x000000010014e26c in event_process_active_single_queue (base=0x1003000a0, activeq=0x100300320) at event.c:1303
#3  0x000000010014e85b in event_process_active (base=0x1003000a0) at event.c:1396
#4  0x000000010014ee40 in opal_libevent2013_event_base_loop (base=0x1003000a0, flags=1) at event.c:1593
#5  0x0000000100001bbe in main (argc=1, argv=0x7fff5fbff398) at evpri-test.c:110

This is clearly not a problem in libevent itself, but I'm rather lost as to the cause. Only thing I can think is that both of the termination events reference -1 as their fake fd, and perhaps this is causing confusion.

Any thoughts would be most appreciated!
Ralph


Attachment: evpri-test.c
Description: Binary data



On Jan 5, 2012, at 10:28 AM, Nick Mathewson wrote:

> On Wed, Jan 4, 2012 at 2:50 PM, Ralph Castain <rhc@xxxxxxxxxxxx> wrote:
>> Hmmm...Well, your program works fine for me too, and I haven't succeeded in making it crash, so I suspect it is a bug in my code (which is what I expected). I configured with libevent debug enabled, but saw no output from libevent (the code still crashes as before). Is there anything else I need to set to get diagnostic output from libevent?
> 
> Have a look at event_enable_debug_mode()
> 
> 
> best of luck,
> -- 
> Nick
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