[OpenSIPS-Users] opensips udp workers lock up with sched_yield

Fri Feb 28 14:20:03 EST 2020

Bogdan-Andrei, thank you for your insight. Yes, we also use SIP TCP & TLS. I do not see any locks in the rest of the “opensipsctl trap.” Perhaps you will be able to understand it better. The trap is posted at https://pastebin.com/1rs8fVEB

Thank you
William Simon

From: Bogdan-Andrei Iancu <bogdan at opensips.org>
Date: Friday, February 28, 2020 at 4:23 AM
To: OpenSIPS users mailling list <users at lists.opensips.org>, William Simon <wsimon at stratusvideo.com>
Subject: Re: [OpenSIPS-Users] opensips udp workers lock up with sched_yield

Hi William,

That sched_yield translates into waiting for a lock. As the backtrace (a bit crippled) shows as coming from "send_pr_buffer" (which is responsible for sending out on the network the buffer of a SIP msg), I suspect the transport is TCP or TLS (missing frame #1), as they are using locking. So you have the backtraces from all the procs? this will help to identify the proc holding the lock and blocking all the other procs.

Best regards,

Bogdan-Andrei Iancu

OpenSIPS Founder and Developer

  https://www.opensips-solutions.com

OpenSIPS Summit, Amsterdam, May 2020

  https://www.opensips.org/events/Summit-2020Amsterdam/

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On 2/28/20 3:58 AM, William Simon wrote:
In a SIP video environment we have a pair of opensips servers load balancing traffic to freeswitch. The call volume is modest among the two proxies, about 400 concurrent calls at peak times.

We are occasionally seeing opensips lock up and stop responding to SIP traffic. There is no error in the syslog and no indication of resource exhaustion on the VM (it is a 4-core VMware instance with 4GB of RAM). Once opensips locks up, CPU soon reaches 100%, but before that, it was not using even 50% of the CPU.

Get_statistics shows that neither the shared memory nor pkg memory are heavily used. They are set at 64M / 4M

opensipsctl trace shows this on the udp worker threads (children=8 in config – it was previously set to children=4 and showed the same behavior)

[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
0x00007f5b14028bb7 in sched_yield () at ../sysdeps/unix/syscall-template.S:81
#0  0x00007f5b14028bb7 in sched_yield () at ../sysdeps/unix/syscall-template.S:81
No locals.
#1  0x00000000005323a5 in ?? ()
No symbol table info available.
#2  0x00007f5b0ec6c48f in send_pr_buffer () from /usr/lib/x86_64-linux-gnu/opensips/modules/tm.so
No symbol table info available.
#3  0x00007f5b0ec9eb9b in t_forward_nonack () from /usr/lib/x86_64-linux-gnu/opensips/modules/tm.so
No symbol table info available.
#4  0x00007f5b0ec6defe in t_relay_to () from /usr/lib/x86_64-linux-gnu/opensips/modules/tm.so
No symbol table info available.
#5  0x00007f5b0ec815ee in ?? () from /usr/lib/x86_64-linux-gnu/opensips/modules/tm.so
No symbol table info available.
#6  0x000000000042b20a in do_action ()
No symbol table info available.
#7  0x0000000000430590 in run_action_list ()
No symbol table info available.
#8  0x000000000046d3bc in ?? ()
No symbol table info available.
#9  0x000000000046cc1d in eval_expr ()
No symbol table info available.
#10 0x000000000046cc39 in eval_expr ()
No symbol table info available.
#11 0x000000000046cc09 in eval_expr ()
No symbol table info available.
#12 0x000000000042b19a in do_action ()
No symbol table info available.
#13 0x0000000000430590 in run_action_list ()
No symbol table info available.
#14 0x00000000004306ba in ?? ()
No symbol table info available.
#15 0x000000000042da9a in do_action ()
No symbol table info available.
#16 0x0000000000430590 in run_action_list ()
No symbol table info available.
#17 0x000000000042e62e in do_action ()
No symbol table info available.
#18 0x0000000000430590 in run_action_list ()
No symbol table info available.
#19 0x000000000042e62e in do_action ()
No symbol table info available.
#20 0x0000000000430590 in run_action_list ()
No symbol table info available.
#21 0x00000000004308d0 in run_top_route ()
No symbol table info available.
#22 0x0000000000436ef3 in receive_msg ()
No symbol table info available.
#23 0x000000000052d5c5 in ?? ()
No symbol table info available.
#24 0x000000000051536d in ?? ()
No symbol table info available.
#25 0x000000000051837a in udp_rcv_loop ()
No symbol table info available.
#26 0x0000000000519c38 in udp_start_processes ()
No symbol table info available.
#27 0x000000000041c38a in main ()
No symbol table info available.
---end 82753 -------------------------------------------------------

We also find no evidence in network captures of any network problem or anomalous SIP packet that could be causing a problem. How can we troubleshoot this? The only way to recover the service is to restart opensips.

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