[SR-Users] R: R: Kamailio connection issue

Tomas Zanet tzanet at came.com
Mon Mar 9 11:23:41 CET 2020 

Hi All, thanks for your replies. As suggested I did the following steps:
1) Checked our backend and now, after creating some indexes, is running properly with the right query time
2) Increased the connection limit to 64K in kamailio.cfg file
3) Set tcp_connection_lifetime to 5s for new connection and once a sip client gets registered it’s increased to 3605s
4) Set tcp_connect_timeout=2 and tcp_send_timeout = 2
5) Added tcp_keepalive as suggested
but the issue still persists.

I've also checked our kernel settings which are the same as described in doc/tutorials/tcp_tunning.txt.

I haven't used async module which can be used for sending push notification yet because this issue happens also when the system is in idle with no calls in progress.

Kamailio processes (tcp main and receivers) are not running with high CPU (1-2% of CPU load) but sometimes tcp_main process gets our app connection after some seconds....it causes delayed app registration which lead to have some missed calls, because calls are closed before app gets registered.

In the kamailio log file there are the same warning messages described below, in which tcp_main is not able to find free tcp receivers.
Mar  4 15:40:23 server-xip-01 /usr/local/sbin/kamailio[29417]: DEBUG: <core> [tcp_main.c:3816]: send2child(): WARNING: no free tcp receiver, connection passed to the least busy one (20)

Moreover the tcp_main thread, which should be the thread that handles the incoming connection, is always busy to release the connections got from its children processes
Mar  6 07:53:30 server-xip-01 /usr/local/sbin/kamailio[1845]: DEBUG: <core> [io_wait.h:380]: io_watch_add(): DBG: io_watch_add(0xa20dc0, 3975, 2, 0x7f19e6d6d2b8), fd_no=3922
Mar  6 07:53:30 server-xip-01 /usr/local/sbin/kamailio[1845]: DEBUG: <core> [tcp_main.c:3378]: handle_tcp_child(): CONN_RELEASE  0x7f19e6d6d2b8 refcnt= 1
Mar  6 07:53:30 server-xip-01 /usr/local/sbin/kamailio[1845]: DEBUG: <core> [io_wait.h:602]: io_watch_del(): DBG: io_watch_del (0xa20dc0, 2272, -1, 0x0) fd_no=3923 called

Any ideas what could cause this behaviour?

Many thanks
T.


Tomas Zanet
R&D Software Designer
tzanet at came.com
CAME S.p.A.


Da: sr-users [mailto:sr-users-bounces at lists.kamailio.org] Per conto di M S
Inviato: mercoledì 4 marzo 2020 20:10
A: Kamailio (SER) - Users Mailing List <sr-users at lists.kamailio.org>
Oggetto: Re: [SR-Users] R: Kamailio connection issue

You have many problems,

1. You do not seem to have TCP keepalives setup. So idle TCP connections may be disrupted, closed or reset by any router on the internet, forcing SIP client to re-register. As a result many more tcp connections are created by a single SIP end point then expected. You said you have 5K active users with 8K connection limit, which is way too low. The limit should be at least more then twice the active users (12.5K in your case). I usually just set it to maximum i.e. 64K.

2. TCP connection life time of 3605 seconds is way too high. There will be many many hack attempts on your server, some users will enter wrong password, some users change their network (and thus need to re-register), so allowing 3605 seconds life time for ALL of them is a HUGE mistake, and you will run out of connection limit pretty quick. So keep the life time as small as possible 5 or 10 seconds (approx. max time the server takes to process sip register x 20 e.g. 250ms x 20 = 5000 ms = 5 seconds). Once the SIP client successfully registers, you can increase the TCP life time using,

https://kamailio.org/docs/modules/4.4.x/modules/tcpops.html#tcpops.f.tcp_set_connection_lifetime

3. Similarly setup TCP keepalives according to SIP Register success,

https://kamailio.org/docs/modules/4.4.x/modules/tcpops.html#tcpops.f.tcp_keepalive_enable
https://kamailio.org/docs/modules/4.4.x/modules/tcpops.html#tcpops.f.tcp_keepalive_disable

4. If average SIP packet processing time is too high e.g. due to slow db connection for authentication etc. push notification setup, web queries etc. then use ASYNC for all time consuming tasks. So TCP listener processes get freed quickly and can process more new connections.

5. It's good to monitor and analyze TCP connection states and events, especially when TCP connections closes and why? See the TCPOPS module for more help.

Hope this helps.



On Wed, Mar 4, 2020 at 5:30 PM Tomas Zanet <tzanet at came.com> wrote:
As you suggested I increased the debug level from -1 to 3 and I got this Kamailio log:
Mar  4 15:40:21 server-xip-01 /usr/local/sbin/kamailio[29417]: DEBUG: <core> [io_wait.h:602]: io_watch_del(): DBG: io_watch_del (0xa20dc0, 3433, -1, 0x0) fd_no=2922 called
Mar  4 15:40:21 server-xip-01 /usr/local/sbin/kamailio[29417]: DEBUG: <core> [tcp_main.c:4139]: handle_tcpconn_ev(): sending to child, events 1
Mar  4 15:40:21 server-xip-01 /usr/local/sbin/kamailio[29417]: DEBUG: <core> [tcp_main.c:3816]: send2child(): WARNING: no free tcp receiver, connection passed to the least busy one (30)
Mar  4 15:40:21 server-xip-01 /usr/local/sbin/kamailio[29417]: DEBUG: <core> [tcp_main.c:3821]: send2child(): selected tcp worker 8 36(29409) for activity on [tls:X.X.X.X:5061], 0x7f482c2c2bc0
Mar  4 15:40:21 server-xip-01 /usr/local/sbin/kamailio[29409]: DEBUG: <core> [tcp_read.c:1576]: handle_io(): received n=8 con=0x7f482c2c2bc0, fd=13
Mar  4 15:40:21 server-xip-01 /usr/local/sbin/kamailio[29409]: DEBUG: tls [tls_server.c:197]: tls_complete_init(): completing tls connection initialization
Mar  4 15:40:21 server-xip-01 /usr/local/sbin/kamailio[29409]: DEBUG: tls [tls_server.c:226]: tls_complete_init(): Using initial TLS domain TLSs<default> (dom 0x7f481b22ba50 ctx 0x7f481b6fbf20 sn [])
Mar  4 15:40:21 server-xip-01 /usr/local/sbin/kamailio[29409]: DEBUG: tls [tls_domain.c:715]: sr_ssl_ctx_info_callback(): SSL handshake started

Looking for this warning into the log, I realized that there are a lot of these messages:

sudo tail -f /var/log/kamailio.log | grep "no free tcp receiver"
Mar  4 15:40:23 server-xip-01 /usr/local/sbin/kamailio[29417]: DEBUG: <core> [tcp_main.c:3816]: send2child(): WARNING: no free tcp receiver, connection passed to the least busy one (20)
Mar  4 15:40:23 server-xip-01 /usr/local/sbin/kamailio[29417]: DEBUG: <core> [tcp_main.c:3816]: send2child(): WARNING: no free tcp receiver, connection passed to the least busy one (20)
Mar  4 15:40:23 server-xip-01 /usr/local/sbin/kamailio[29417]: DEBUG: <core> [tcp_main.c:3816]: send2child(): WARNING: no free tcp receiver, connection passed to the least busy one (21)
Mar  4 15:40:23 server-xip-01 /usr/local/sbin/kamailio[29417]: DEBUG: <core> [tcp_main.c:3816]: send2child(): WARNING: no free tcp receiver, connection passed to the least busy one (20)
Mar  4 15:40:23 server-xip-01 /usr/local/sbin/kamailio[29417]: DEBUG: <core> [tcp_main.c:3816]: send2child(): WARNING: no free tcp receiver, connection passed to the least busy one (21)
Mar  4 15:40:24 server-xip-01 /usr/local/sbin/kamailio[29417]: DEBUG: <core> [tcp_main.c:3816]: send2child(): WARNING: no free tcp receiver, connection passed to the least busy one (14)
Mar  4 15:40:24 server-xip-01 /usr/local/sbin/kamailio[29417]: DEBUG: <core> [tcp_main.c:3816]: send2child(): WARNING: no free tcp receiver, connection passed to the least busy one (15)
Mar  4 15:40:24 server-xip-01 /usr/local/sbin/kamailio[29417]: DEBUG: <core> [tcp_main.c:3816]: send2child(): WARNING: no free tcp receiver, connection passed to the least busy one (16)
Mar  4 15:40:24 server-xip-01 /usr/local/sbin/kamailio[29417]: DEBUG: <core> [tcp_main.c:3816]: send2child(): WARNING: no free tcp receiver, connection passed to the least busy one (16)
Mar  4 15:40:24 server-xip-01 /usr/local/sbin/kamailio[29417]: DEBUG: <core> [tcp_main.c:3816]: send2child(): WARNING: no free tcp receiver, connection passed to the least busy one (16)
Mar  4 15:40:24 server-xip-01 /usr/local/sbin/kamailio[29417]: DEBUG: <core> [tcp_main.c:3816]: send2child(): WARNING: no free tcp receiver, connection passed to the least busy one (17)
Mar  4 15:40:24 server-xip-01 /usr/local/sbin/kamailio[29417]: DEBUG: <core> [tcp_main.c:3816]: send2child(): WARNING: no free tcp receiver, connection passed to the least busy one (17)
Mar  4 15:40:24 server-xip-01 /usr/local/sbin/kamailio[29417]: DEBUG: <core> [tcp_main.c:3816]: send2child(): WARNING: no free tcp receiver, connection passed to the least busy one (17)
Mar  4 15:40:24 server-xip-01 /usr/local/sbin/kamailio[29417]: DEBUG: <core> [tcp_main.c:3816]: send2child(): WARNING: no free tcp receiver, connection passed to the least busy one (16)
Mar  4 15:40:24 server-xip-01 /usr/local/sbin/kamailio[29417]: DEBUG: <core> [tcp_main.c:3816]: send2child(): WARNING: no free tcp receiver, connection passed to the least busy one (17)
Mar  4 15:40:24 server-xip-01 /usr/local/sbin/kamailio[29417]: DEBUG: <core> [tcp_main.c:3816]: send2child(): WARNING: no free tcp receiver, connection passed to the least busy one (18)
Mar  4 15:40:24 server-xip-01 /usr/local/sbin/kamailio[29417]: DEBUG: <core> [tcp_main.c:3816]: send2child(): WARNING: no free tcp receiver, connection passed to the least busy one (18)
Mar  4 15:40:24 server-xip-01 /usr/local/sbin/kamailio[29417]: DEBUG: <core> [tcp_main.c:3816]: send2child(): WARNING: no free tcp receiver, connection passed to the least busy one (18)
Mar  4 15:40:24 server-xip-01 /usr/local/sbin/kamailio[29417]: DEBUG: <core> [tcp_main.c:3816]: send2child(): WARNING: no free tcp receiver, connection passed to the least busy one (18)
Mar  4 15:40:24 server-xip-01 /usr/local/sbin/kamailio[29417]: DEBUG: <core> [tcp_main.c:3816]: send2child(): WARNING: no free tcp receiver, connection passed to the least busy one (18)
Mar  4 15:40:24 server-xip-01 /usr/local/sbin/kamailio[29417]: DEBUG: <core> [tcp_main.c:3816]: send2child(): WARNING: no free tcp receiver, connection passed to the least busy one (18)
…..
….

As far as I know, I should increase the tcp_children parameter, right?.
Now, it’s set to 16 but it’s pretty clear which is not enough. I increased it step by step till 48 but that’s still not enough.
If I set it to 64 then Kamailio failed to start.

What would you recommend for a server which has more or less 5K users?

Many thanks.
T.

Tomas Zanet
R&D Software Designer
tzanet at came.com



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Da: sr-users [mailto:sr-users-bounces at lists.kamailio.org] Per conto di Denys Pozniak
Inviato: mercoledì 4 marzo 2020 15:00
A: Kamailio (SER) - Users Mailing List <sr-users at lists.kamailio.org>
Oggetto: Re: [SR-Users] Kamailio connection issue

Hello!
You can try to increase the debug printing level (like debug=2 or even debug=3) and check syslog when Kamailio gets stuck.


ср, 4 мар. 2020 г. в 13:12, Tomas Zanet <tzanet at came.com>:
Hi All,

In these days I'm facing an issue or a misconfiguration, I don't know, with our remote apps (SIP clients) and our cloud server in which there's a Kamailio version 4.4.4.
Sometimes our app takes some seconds (about 10-12sec) to connect to the Kamailio socket (sips on 5061) and our app is stuck on connect sytem call.

To debug this behaviour I put a rule in the iptable like this:
sudo iptables -I INPUT -p tcp -m tcp --dport 5061 -m state --state NEW  -j LOG --log-level 1 --log-prefix "New Connection "

when everything goes well, there is one row which describes the new incoming connection Mar  4 07:08:40 server-xip-01 kernel: New Connection IN=eth0 OUT= MAC=bc:76:4e:20:1f:fb:e8:ed:f3:3a:52:41:08:00 SRC=X.X.X.X DST=Y.Y.Y.Y LEN=64 TOS=0x00 PREC=0x00 TTL=45 ID=0 DF PROTO=TCP SPT=15819 DPT=5061 WINDOW=65535 RES=0x00 CWR ECE SYN URGP=0

when our app gets stuck in the connect, there are many attempts and seems that Kamailio is not ready to accept this connection:
Mar  4 07:11:54 server-xip-01 kernel: New Connection IN=eth0 OUT= MAC=bc:76:4e:20:1f:fb:e8:ed:f3:3a:52:41:08:00 SRC=X.X.X.X DST=Y.Y.Y.Y LEN=64 TOS=0x00 PREC=0x00 TTL=45 ID=0 DF PROTO=TCP SPT=52900 DPT=5061 WINDOW=65535 RES=0x00 CWR ECE SYN URGP=0 Mar  4 07:11:54 server-xip-01 kernel: New Connection IN=eth0 OUT= MAC=bc:76:4e:20:1f:fb:e8:ed:f3:3a:52:41:08:00 SRC=X.X.X.X DST=Y.Y.Y.Y LEN=64 TOS=0x00 PREC=0x00 TTL=45 ID=0 DF PROTO=TCP SPT=52900 DPT=5061 WINDOW=65535 RES=0x00 SYN URGP=0 Mar  4 07:11:55 server-xip-01 kernel: New Connection IN=eth0 OUT= MAC=bc:76:4e:20:1f:fb:e8:ed:f3:3a:52:41:08:00 SRC=X.X.X.X DST=Y.Y.Y.Y LEN=64 TOS=0x00 PREC=0x00 TTL=45 ID=0 DF PROTO=TCP SPT=52900 DPT=5061 WINDOW=65535 RES=0x00 SYN URGP=0 Mar  4 07:11:55 server-xip-01 kernel: New Connection IN=eth0 OUT= MAC=bc:76:4e:20:1f:fb:e8:ed:f3:3a:52:41:08:00 SRC=X.X.X.X DST=Y.Y.Y.Y LEN=64 TOS=0x00 PREC=0x00 TTL=45 ID=0 DF PROTO=TCP SPT=52900 DPT=5061 WINDOW=65535 RES=0x00 SYN URGP=0 Mar  4 07:11:55 server-xip-01 kernel: New Connection IN=eth0 OUT= MAC=bc:76:4e:20:1f:fb:e8:ed:f3:3a:52:41:08:00 SRC=X.X.X.X DST=Y.Y.Y.Y LEN=64 TOS=0x00 PREC=0x00 TTL=45 ID=0 DF PROTO=TCP SPT=52900 DPT=5061 WINDOW=65535 RES=0x00 SYN URGP=0 Mar  4 07:11:56 server-xip-01 kernel: New Connection IN=eth0 OUT= MAC=bc:76:4e:20:1f:fb:e8:ed:f3:3a:52:41:08:00 SRC=X.X.X.X DST=Y.Y.Y.Y LEN=64 TOS=0x00 PREC=0x00 TTL=45 ID=0 DF PROTO=TCP SPT=52900 DPT=5061 WINDOW=65535 RES=0x00 SYN URGP=0 Mar  4 07:11:56 server-xip-01 kernel: New Connection IN=eth0 OUT= MAC=bc:76:4e:20:1f:fb:e8:ed:f3:3a:52:41:08:00 SRC=X.X.X.X DST=Y.Y.Y.Y LEN=64 TOS=0x00 PREC=0x00 TTL=45 ID=0 DF PROTO=TCP SPT=52900 DPT=5061 WINDOW=65535 RES=0x00 SYN URGP=0 Mar  4 07:11:56 server-xip-01 kernel: New Connection IN=eth0 OUT= MAC=bc:76:4e:20:1f:fb:e8:ed:f3:3a:52:41:08:00 SRC=X.X.X.X DST=Y.Y.Y.Y LEN=64 TOS=0x00 PREC=0x00 TTL=45 ID=0 DF PROTO=TCP SPT=52900 DPT=5061 WINDOW=65535 RES=0x00 SYN URGP=0 Mar  4 07:11:58 server-xip-01 kernel: New Connection IN=eth0 OUT= MAC=bc:76:4e:20:1f:fb:e8:ed:f3:3a:52:41:08:00 SRC=X.X.X.X DST=Y.Y.Y.Y LEN=64 TOS=0x00 PREC=0x00 TTL=45 ID=0 DF PROTO=TCP SPT=52900 DPT=5061 WINDOW=65535 RES=0x00 SYN URGP=0 Mar  4 07:12:00 server-xip-01 kernel: New Connection IN=eth0 OUT= MAC=bc:76:4e:20:1f:fb:e8:ed:f3:3a:52:41:08:00 SRC=X.X.X.X DST=Y.Y.Y.Y LEN=64 TOS=0x00 PREC=0x00 TTL=45 ID=0 DF PROTO=TCP SPT=52900 DPT=5061 WINDOW=65535 RES=0x00 SYN URGP=0 Mar  4 07:12:05 server-xip-01 kernel: New Connection IN=eth0 OUT= MAC=bc:76:4e:20:1f:fb:e8:ed:f3:3a:52:41:08:00 SRC=X.X.X.X DST=Y.Y.Y.Y LEN=48 TOS=0x00 PREC=0x00 TTL=45 ID=0 DF PROTO=TCP SPT=52900 DPT=5061 WINDOW=65535 RES=0x00 SYN URGP=0 When it happens our app takes more than 10 sec to connect to the Kamailio socket.

I tried to increase the children configuration parameter in the cfg file because I thought there were not enough tcp receiver but with no luck.
Here are some configuration parameters:

children = 16 // was 8 before found this issue

# life time of TCP connection when there is no traffic # - a bit higher than registration expires to cope with UA behind NAT
tcp_connection_lifetime=3605

open_files_limit=8192

tcp_max_connections=8192
tls_max_connections=8192

Here is the output of the ulimit command:
ulimit -a
core file size          (blocks, -c) 0
data seg size           (kbytes, -d) unlimited
scheduling priority             (-e) 0
file size               (blocks, -f) unlimited
pending signals                 (-i) 31393
max locked memory       (kbytes, -l) 64
max memory size         (kbytes, -m) unlimited
open files                      (-n) 65535
pipe size            (512 bytes, -p) 8
POSIX message queues     (bytes, -q) 819200
real-time priority              (-r) 0
stack size              (kbytes, -s) 8192
cpu time               (seconds, -t) unlimited
max user processes              (-u) 31393
virtual memory          (kbytes, -v) unlimited
file locks                      (-x) unlimited
In the kamailio log file I don't see anything wrong, I don't see messages like "[tcp_main.c:3913]: handle_new_connect(): maximum number of tls connections exceeded".

Here is the output of kamctl ps command
Process::  ID=0 PID=11725 Type=main process - attendant
Process::  ID=1 PID=11727 Type=udp receiver child=0 sock=10.208.194.26:5061
Process::  ID=2 PID=11728 Type=udp receiver child=1 sock=10.208.194.26:5061
Process::  ID=3 PID=11729 Type=udp receiver child=2 sock=10.208.194.26:5061
Process::  ID=4 PID=11730 Type=udp receiver child=3 sock=10.208.194.26:5061
Process::  ID=5 PID=11731 Type=udp receiver child=4 sock=10.208.194.26:5061
Process::  ID=6 PID=11732 Type=udp receiver child=5 sock=10.208.194.26:5061
Process::  ID=7 PID=11733 Type=udp receiver child=6 sock=10.208.194.26:5061
Process::  ID=8 PID=11734 Type=udp receiver child=7 sock=10.208.194.26:5061
Process::  ID=9 PID=11735 Type=udp receiver child=8 sock=10.208.194.26:5061
Process::  ID=10 PID=11736 Type=udp receiver child=9 sock=10.208.194.26:5061
Process::  ID=11 PID=11737 Type=udp receiver child=10 sock=10.208.194.26:5061
Process::  ID=12 PID=11738 Type=udp receiver child=11 sock=10.208.194.26:5061
Process::  ID=13 PID=11739 Type=udp receiver child=12 sock=10.208.194.26:5061
Process::  ID=14 PID=11740 Type=udp receiver child=13 sock=10.208.194.26:5061
Process::  ID=15 PID=11741 Type=udp receiver child=14 sock=10.208.194.26:5061
Process::  ID=16 PID=11742 Type=udp receiver child=15 sock=10.208.194.26:5061
Process::  ID=17 PID=11743 Type=slow timer
Process::  ID=18 PID=11744 Type=timer
Process::  ID=19 PID=11745 Type=secondary timer
Process::  ID=20 PID=11746 Type=MI FIFO
Process::  ID=21 PID=11747 Type=USRLOC Timer
Process::  ID=22 PID=11748 Type=USRLOC Timer
Process::  ID=23 PID=11749 Type=USRLOC Timer
Process::  ID=24 PID=11750 Type=USRLOC Timer
Process::  ID=25 PID=11751 Type=ctl handler
Process::  ID=26 PID=11752 Type=RTIMER SEC EXEC
Process::  ID=27 PID=11753 Type=TIMER NH
Process::  ID=28 PID=11754 Type=tcp receiver (generic) child=0
Process::  ID=29 PID=11755 Type=tcp receiver (generic) child=1
Process::  ID=30 PID=11756 Type=tcp receiver (generic) child=2
Process::  ID=31 PID=11757 Type=tcp receiver (generic) child=3
Process::  ID=32 PID=11758 Type=tcp receiver (generic) child=4
Process::  ID=33 PID=11759 Type=tcp receiver (generic) child=5
Process::  ID=34 PID=11760 Type=tcp receiver (generic) child=6
Process::  ID=35 PID=11761 Type=tcp receiver (generic) child=7
Process::  ID=36 PID=11762 Type=tcp receiver (generic) child=8
Process::  ID=37 PID=11763 Type=tcp receiver (generic) child=9
Process::  ID=38 PID=11764 Type=tcp receiver (generic) child=10
Process::  ID=39 PID=11765 Type=tcp receiver (generic) child=11
Process::  ID=40 PID=11766 Type=tcp receiver (generic) child=12
Process::  ID=41 PID=11767 Type=tcp receiver (generic) child=13
Process::  ID=42 PID=11768 Type=tcp receiver (generic) child=14
Process::  ID=43 PID=11769 Type=tcp receiver (generic) child=15
Process::  ID=44 PID=11770 Type=tcp main process


Can anyone address me to find out this happens, please?
Please let me know if you need further information...

Thanks in advance,
Best Regards
Tomas



Tomas Zanet
R&D Software Designer
tzanet at came.com
CAME S.p.A.

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BR,
Denys Pozniak


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