To my best knowledge, TCP support in Kamailio is blocking. This has been addressed for sip-router (tcp_async=yes). Anyway, there are still some issues for tls.

This is a good argument to switch to sip-router :-)

How many simultaneous TCP connections are you handling? You could try to limit the max number of connections and check the impact on the CPU consumption.

Theoretically we're using few simultaneous client connections (<10). My first intention is to increase tcp_children and to decrease tcp_send_timeout and tcp_connect_timeout. Do you believe it is a good idea ?

Cheers Pascal

Cheers,

Victor Pascual Ávila

2009/5/28 Pascal Maugeri pascal.maugeri@gmail.com:

FYI, I've changed the configuration to:

tcp_children=8 tcp_send_timeout=3 tcp_connect_timeout=5

and it looks we get less often the problem described here ( tcp_connect/send time out error).

This is a good workaround, but the problem is that it replies on the clients behaviour and it shouldn't occur (a server cannot get "blocked" due to clients problems). I hope TCP handling will be improved in SIP-Router.

I confirm that the problem was triggered by the fact that our client is using TCP only and that the tcp connections were unavailable after some presence test (many NOTIFY messages sent to TCP).

I'm curious to know how many children do you use in a typical configuration ? 4, 8, more? Of course it depends on the traffic expected but let me know that this is parameter you always increase in a production environment.

Theorically you can add so many TCP listeners as you desire (depending on your CPU's and memory). But if your environment makes high usage of TCP then increase it as much as possible.

2009/5/29 Pascal Maugeri pascal.maugeri@gmail.com:

May 27 14:20:11 server2-operations /usr/local/sbin/kamailio[26227]: WARNING:core:send2child: no free tcp receiver, connection passed to the leastbusy one (1)

Yes, this is the warning I told about in other mail.

• in top kamailio process have high values in the %CPU column such as 50% or

99% !?

The same occurs (kamailio takes 50-99% CPU) in case there is a problem with MySQL and Kamailio cannot write into it. It seems that when kamailio process must wait for something (TCP connection, MysQL access) it consumes CPU resources (waiting).

• when all kamailio processes have reached this top values, it is impossible

to connect a new client untill we reset kamailio :-/

Makes sense since no TCP listener is available :(

I will try the parameter

modparam("registrar", "tcp_persistent_flag", 7)

It will not solve the issue. The only it does it setting the TCP connection duration for the registration expires time. It has nothing to do with failed TCP connections.

On 1/29/10 8:40 PM, Zunnun wrote:

I have also found this problem with 1.5.3. Modified Kamailio's source code to fix that problem. Now I don't have this problem.

can you send a patch? I will check it and commit it to svn if all ok.

Thanks, Daniel

Pascal Maugeri wrote:

...

Hi

Using Kamailio 1.5 we periodically get the following errors:

Jul 1 09:54:41 localhost /usr/local/sbin/openser[3836]: ERROR:core:tcp_blocking_connect: poll error: flags 18 Jul 1 09:54:41 localhost /usr/local/sbin/openser[3836]: ERROR:core:tcp_blocking_connect: failed to retrieve SO_ERROR (110) Connection timed out Jul 1 09:54:41 localhost /usr/local/sbin/openser[3836]: ERROR:core:tcpconn_connect: tcp_blocking_connect failed Jul 1 09:54:41 localhost /usr/local/sbin/openser[3836]: ERROR:core:tcp_send: connect failed Jul 1 09:54:41 localhost /usr/local/sbin/openser[3836]: ERROR:tm:msg_send: tcp_send failed

They are several emails in this mailing list explaining we should play with tcp parameters. I will try to change my configuration and see if we can solve this issue.

But when this kind of error happen we observe that the kamailio processes are using 100% of CPU (top).

Our client is using SIP over TCP only (no UDP).

Do you have any hint on how to configure Kamailio to improve TCP support ? Is it normal to kamailio processes to overload CPU ?

Regards, Pascal

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