Re: [sr-dev] [Kamailio-Users] kamailio / deadlock3 - sr-dev

28 Jan 2010

I am cc-ing sr-dev, since tcp code is from ser and Andrei may have more 
insights...

On 1/28/10 2:41 PM, Aymeric Moizard wrote:
...

 On Thu, 28 Jan 2010, Henning Westerholt wrote:

  On Thursday 28 January 2010, Aymeric Moizard
wrote:
  here is the backtrace I have. unfortunatly
without debug symbol!
 I found the same for many of the kamailio process. "sched_yield"
 is pending for ever. My system is a debian/etch.

 #0  0xffffe424 in __kernel_vsyscall ()
 #1  0xb7cef4ac in sched_yield () from /lib/tls/i686/cmov/libc.so.6
 #2  0x080a93fd in tcp_send ()
 #3  0xb7975679 in send_pr_buffer () from 
 /usr/lib/kamailio/modules/tm.so
 #4  0xb79789ac in t_forward_nonack () from 
 /usr/lib/kamailio/modules/tm.so
 #5  0xb7974784 in t_relay_to () from /usr/lib/kamailio/modules/tm.so
 #6  0xb7983a11 in load_tm () from /usr/lib/kamailio/modules/tm.so
 #7  0x081cf810 in mem_pool ()
 #8  0x00000000 in ?? ()

 I guess most t_relay operation towards my "mobipouce.com" domain
 with one IP being down breaks each kamailio process one after the
 other... I'm not sure every such t_relay operation is always breaking
 exactly one thread each time.

 I went through the lock/unlock of tcp_main.c but it seems every
 lock has an unlock at least... 
 Hi Aymeric,

 i remember that we observed this "sched_yield" problems on one old 
 0.9 system
 after some time (like weeks or month). We did not found the solution 
 in this
 case, after a restart it was gone again..

 You mentioned in an earlier mail that you see this related to UDP 
 traffic, but
 in the log file and also in your investigations you think its related 
 to TPC? 
 This is the exact case:
 1-> SUBSCRIBE sent to/received by over UDP to kamailio.
 2-> kamailio does a SRV record lookup for "mobipouce.com"
 3-> kamailio try sip2.mobipouce.com (91.199.234.47) over TCP first
 4-> connection failed with logs:
 Jan 27 12:56:38 ns26829 /usr/sbin/kamailio[9763]: 
 ERROR:core:tcp_blocking_connect: poll error: flags 18
 Jan 27 12:56:38 ns26829 /usr/sbin/kamailio[9763]: 
 ERROR:core:tcp_blocking_connect: failed to retrieve SO_ERROR (111) 
 Connection refused
 Jan 27 12:56:38 ns26829 /usr/sbin/kamailio[9763]: 
 ERROR:core:tcpconn_connect: tcp_blocking_connect failed
 Jan 27 12:56:38 ns26829 /usr/sbin/kamailio[9763]: ERROR:core:tcp_send: 
 connect failed
 Jan 27 12:56:38 ns26829 /usr/sbin/kamailio[9763]: ERROR:tm:msg_send: 
 tcp_send failed
 Jan 27 12:56:38 ns26829 /usr/sbin/kamailio[9763]: 
 ERROR:tm:t_forward_nonack: sending request failed
 5-> I guess kamailio is supposed to try other SRV record value:
     sip2.mobipouce.com (91.199.234.46) but it doesn't

 Thus, I'm guessing the issue is related to SRV record with failover OR 
 just tcp failure. Not related to UDP at all. 
so TCP connect failed, the tcp worker returned as it prints the message 
and, to be sure I got it right, the UDP worker (the one that received) 
got blocked?

...

 It's definitly possible to reproduce the issue now!

 I guess anyone can try your version of kamailio and t_relay message
 to "mobipouce.com" and you'll fall in that case! Sending plenty of
 those messages will finally lock all kamailio process. 
All? tcp and udp?

Cheers,
Daniel

...

 Regards,
 Aymeric MOIZARD / ANTISIP
 amsip - http://www.antisip.com
 osip2 - http://www.osip.org
 eXosip2 - http://savannah.nongnu.org/projects/exosip/

  Regards,

 Henning

 Viele Grüße,

 Henning

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