Sofia SIP/503 System Busy

António Silva asilva at
Thu Oct 7 16:47:11 UTC 2021


Recently update a server to Debian 10  with freeswitch git Version 1.10.7-dev git 432bfc0 2021-07-27, and after a few days I start to see lot of expired registers and new invites rejected with “ 503 System Busy”. I restart FS and everything is ok. 
Also no log print in FS console that could point me to the root cause of the issue. 
The server before the update was running debian 8  with freeswitch Version 1.10.4-dev git 546bebb 2020-08-03 and never see this issue.

The hardware of the server is a ProLiant DL165 G7: 
2 x AMD Opteron(tm) Processor 6128,  Cores por CPU: 8,  Cores totales: 16     

The system is not with high load at the time the issue was occurring, fs status report:

freeswitch at srvone> status
UP 0 years, 2 days, 21 hours, 50 minutes, 23 seconds, 264 milliseconds, 655 microseconds
FreeSWITCH (Version 1.10.7-dev git 432bfc0 2021-07-27 19:25:13Z 64bit) is ready
147010 session(s) since startup
86 session(s) - peak 251, last 5min 91 
0 session(s) per Sec out of max 50, peak 26, last 5min 5 
2000 session(s) max
min idle cpu 5.00/66.57
Current Stack Size/Max 240K/8192K

From the source code, Sofia.c:2496
			if (switch_queue_size(mod_sofia_globals.msg_queue) > (unsigned int)critical) {
				nua_respond(nh, 503, "System Busy", SIPTAG_RETRY_AFTER_STR("300"), NUTAG_WITH_THIS(nua), TAG_END());
				goto end;

So the trigger here is the msg_queue hitting the critical value, for what I could check in the source code, is the value of 7200. 
This value is the maximum number of sip dialogs that FS can handle?

I’ve some endpoints registered using TCP, can they affect the msg_queue?  

I can’t think of a route cause for this issue… any hint? 

Thanks for the help. 

Saludos / Regards / Cumprimentos
António Silva

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