[SR-Users] Huge TLS performance regression migrating from 3.3.7 to 4.2.6

[Tristan Mahé]

Hi List,

I've been reaching a strange thing lately, trying to upgrade to kamailio
4.2.6 ( identical config ):

- 35% loss of performance on TLS connections ( Sipp REGISTER scenario,
easily reproduced ).
- more TCP workers needed to ease the TCP queues ( 32 workers on 3.3.7,
at least 64 are needed on 4.2.6 to avoid "queue full" messages in logs ).
- kamailio 4.2.6 intermittent processing of requests ( Kamailio stops
accepting new tcp connections, then resume a bit later, then stops
again,... ) => starts happening when Kamailio is treating more than 20k
tcp connections, with between 500-1k req/s. During those periods, trying
to connect to kamailio with an openssl s_client -connect will end up in
a timeout or with a long delay before the certificate is received ( 03
CONNECTED ).
- kamailio 4.2.6 dropping connections, kamailio 3.3.7 keeping those
connections: after a while, the number of active connections starts to
decrease on kam4, on kam3 it stays constant.

I was wondering if I was alone in this situation or if someone else is
impacted, has some advices ?

It does not seem to be a config issue, as it is the same that was
deployed with both versions.

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