[Asterisk-Dev] Unlocking the unlocked...

[Guillermo Winkler]

Hi,
    Under the following scenario:

6000 outgoing calls/hour(SIP-->ZAP)
75% connected (25% is busy or no answer)
100% of connected calls beign recorded, when LINK event occurs.
P4 2.8 HT.
Krnl 2.4.21

We are having some "Avoid deadlock" issues(This is not happening without 
recording)

As you can see in channel_walk_locked

if (retries < 10)
     ast_log(LOG_DEBUG, "Avoiding initial deadlock for '%s'\n", l->name);
    else
     ast_log(LOG_WARNING, "Avoided initial deadlock for '%s', %d 
retries!\n", l->name, retries);
    ast_mutex_unlock(&chlock);

Ten 1ms retries are done to avoid deadlocks. But when recording is enabled, 
the channel gets locked on start:
 if (ast_monitor_start(c, format, fname, 1)) {
  if (ast_monitor_change_fname(c, fname, 1)) {

Those ten retries are not enough in that case, using lock instead of 
try_lock, or increasing the number of retries, solves the problem 
temporarily.

I wanted to know if someone else is experimenting something similar?

I think ast_channel_walk_locked and ast_get_channel_by_name_locked could be 
rewritten or a new set of functions be added , faster and more reliable (now 
you don't know if the channel you're looking for is not there at all or a 
deadlock(not so dead) issue on ANOTHER channel was the failure).

If you feel the same I would be glad to help.

Regards,
Guillermo