[sr-dev] Kamailio rls module issues

Alex Hermann alex at speakup.nl
Thu Dec 16 09:40:25 CET 2010

On Wednesday 15 December 2010 18:11:40 Daniel-Constantin Mierla wrote:
> About one year ago I did quite some fixes, so looking to see if there
> are any ports from forks might not be wise. It is better to directly
> report the issue and I can take care. To my knowledge, Alex Hermann
> reported some potential race when sending requests via tm on sourceforge
> tracker with a patch, but was not providing the proper fix - I should
> review that issue as well.

The problem with Kamailio's presence is that it has locking issues. Pua as 
well as presence itself lock structures while waiting for a reply. If multiple 
presence updates arrive for the same presentity while the lock is still held, 
Kamailio will get in a loop consuming 100% cpu.

While I was trying to fix this, Anca Vamanu was at the same time fixing the 
issue in Opensips. Her solution was a bit cleaner than mine so I ported some 
of the pua fixes to Kamailio and improved them, but they still need some care. 
Unfortunately I ran out of time.

Bottom line of the solution is to create a queue of updates for each 
presentity and feed them one by one to the pua/presence core without locking 
while waiting for a reply.

Alex Hermann

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