[OpenSIPS-Devel] TCP connection behavior

[Răzvan Crainea]

Hi, Dan!

This is the intended behavior, since OpenSIPS 1.8 (or 1.11, can't 
remember for sure).
In order to avoid moving TCP connections from one process to the other 
answer, when data is sent to a TCP connection, that connection is moved 
to a TCP worker and is kept by that process for a while. It is only 
moved back to the main if the connection is idle.
Regarding the file descriptors, it is normal to have different values in 
different processes, as each process has its own file descriptors table.

Best regards,
Răzvan

On 5/21/19 2:55 PM, Dan Pascu wrote:
> 
> I noticed TCP connections behave differently now. Not sure if it's intentional or a problem.
> 
> Before, all TCP connections were hold by the TCP Main process and they would be passed to TCP receiver processes when some message was received, at which point the TCP receiver would process the message and then pass the connection back to TCP main when it was done. If I used lsof or netstat they would should the connections belonging to TCP main and occasionally being moved to a TCP receiver and back as messages arrived.
> 
> In the latest git version I see the connections under both TCP main and the TCP receivers all the time (even when there are no messages to process) if I look with lsof. If I look with netstat, then the connections are all listen under various TCP receiver processes and none under TCP main.
> 
> Even more weird, the file descriptor for the same connection is different under TCP receiver and TCP main in lsof.
> 
> Here are my processes:
> 
>          {
>              "ID": 10,
>              "PID": 21441,
>              "Type": "TCP receiver"
>          },
>          {
>              "ID": 11,
>              "PID": 21442,
>              "Type": "TCP receiver"
>          },
>          {
>              "ID": 16,
>              "PID": 21450,
>              "Type": "TCP main"
>          }
> 
> And these are the TCP connections (the output never changes, the connections do not seem to be moved between TCP main and a TCP receiver and back anymore):
> 
> $ sudo netstat -pan | grep opensips | grep tcp
> tcp        0      0 81.23.228.160:5060      0.0.0.0:*               LISTEN      21430/./opensips
> tcp        0      0 81.23.228.160:5061      0.0.0.0:*               LISTEN      21430/./opensips
> tcp        0      0 81.23.228.160:5060      86.121.160.133:44102    ESTABLISHED 21441/./opensips
> tcp        0      0 81.23.228.160:5060      152.156.209.166:56317   ESTABLISHED 21442/./opensips
> 
> (notice how all established connections belong only to TCP receiver processes according to netstat)
> 
> $ sudo lsof -np 21450 | grep TCP # This is TCP main
> opensips 21450 opensips  116u     IPv4          580308849      0t0       TCP 81.23.228.160:sip->86.121.160.133:44102 (ESTABLISHED)
> opensips 21450 opensips  117u     IPv4          580313129      0t0       TCP 81.23.228.160:sip->152.156.209.166:56317 (ESTABLISHED)
> opensips 21450 opensips  159u     IPv4          580280113      0t0       TCP 81.23.228.160:sip (LISTEN)
> opensips 21450 opensips  160u     IPv4          580280114      0t0       TCP 81.23.228.160:sip-tls (LISTEN)
> 
> $ sudo lsof -np 21441 | grep TCP # This is the first TCP receiver
> opensips 21441 opensips    5u     IPv4          580308849      0t0       TCP 81.23.228.160:sip->86.121.160.133:44102 (ESTABLISHED)
> opensips 21441 opensips  159u     IPv4          580280113      0t0       TCP 81.23.228.160:sip (LISTEN)
> opensips 21441 opensips  160u     IPv4          580280114      0t0       TCP 81.23.228.160:sip-tls (LISTEN)
> 
> $ sudo lsof -np 21442 | grep TCP # This is the 2nd TCP receiver
> opensips 21442 opensips    5u     IPv4          580313129      0t0       TCP 81.23.228.160:sip->152.156.209.166:56317 (ESTABLISHED)
> opensips 21442 opensips  159u     IPv4          580280113      0t0       TCP 81.23.228.160:sip (LISTEN)
> opensips 21442 opensips  160u     IPv4          580280114      0t0       TCP 81.23.228.160:sip-tls (LISTEN)
> 
> As mentioned before, the output is stable and it doesn't change until the connection is closed. The connections do not seem to be moved back to TCP main. Also notice the file descriptor being 5 in the TCP receiver process and something like 116/117 in TCP main.
> 
> Otherwise TCP connections seem to work, but I noticed the behavior changed from what it used to be in previous versions. Is this an issue, or is it intended?
> 
> --
> Dan
> 
> 
> 
> 
> 
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> 

-- 
Răzvan Crainea
OpenSIPS Core Developer
   http://www.opensips-solutions.com
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