[Freeswitch-dev] Possible deadlock in src/switch_event.c ?

[Karol Golab]

   Well, I have a Perl script run as part of a dialplan and the script 
creates an EventConsumer. Thus I have one bind / unbind pair for each 
connection. Is this somehow wrong / against what the EventConsumer API 
was planned for?
   How could I have a single bind/unbind in this case?

   As for choosing event socket and C application vs a script - what is 
the main difference / reason to switch: performance of some other 
issues? My CPU seems to have some cycles to spare.

   Regards,
   Karol


On 11/28/2011 05:36 PM, Anthony Minessale wrote:
> you're probably right but I wonder what you are doing that is binding 
> and unbinding so much?
> The bind and unbind was designed to be called once when the module is 
> loaded and called again when it exits.
>
> My fear is you are using the embedded scripting event handers in some 
> quick repeating fashion.
>
> I did a commit to flip that case around but I don't encourage you to 
> use embedded scripts for heavy event traffic, that's what event socket 
> is for and if you have the C skills to debug this, you might want to 
> try a C app ;)
>
>
> 2011/11/28 Brian West <brian at freeswitch.org <mailto:brian at freeswitch.org>>
>
>     Please post it to jira.freeswitch.org <http://jira.freeswitch.org>
>
>     /b
>
>     On Nov 28, 2011, at 2:31 AM, Karol Golab wrote:
>
>>
>>       Hi!
>>
>>       I've noticed some strange code in src/switch_event.c - could
>>     someone
>>     smarter (& knowing the mentioned code) please take a look?
>>
>>       The problem is in the order of calls to locks BLOCK & RWLOCK - it
>>     differs between functions:
>>
>>     switch_event_bind_removable
>>             switch_mutex_lock(BLOCK);
>>             switch_thread_rwlock_wrlock(RWLOCK);
>>
>>     switch_event_unbind_callback
>>         switch_thread_rwlock_wrlock(RWLOCK);
>>         switch_mutex_lock(BLOCK);
>>
>>     switch_event_unbind
>>         switch_thread_rwlock_wrlock(RWLOCK);
>>         switch_mutex_lock(BLOCK);
>>
>>       As I understand this may lead to an outright deadlock between bind
>>     and unbind.
>>
>>       I stumbled upon this code while debugging what seems like deadlocks
>>     in our test FS installation put under some heavy load. The load
>>     is about
>>     25 new event subscribers per second (destroyed few seconds later) and
>>     about 700 events per second.
>>
>>       Regards,
>>       Karol
>
>
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   Karol

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