On 28/09/22 23:11, Punyasloka Arya wrote:
We have our squid 3.5 proxy running on centos 6 for 500 users
Desktop video conference application Microsoft Team Meetings sessions and
other VC apps often get disconnected. Audio goes off and reconnects
automatically.
At the same time browsing and other applications work fine.
At the same time SQUID load is normal. we are clueless where to look into the
system
Any clues to fine tune the underlying parameters like File desriptors, cahce
parameters etc.
Please first check whether Squid is actually involved with those
software transactions. Typically those type of communications should be
using RTSP/RTMP or VoIP protocols which Squid-3 does not support.
When Squid-3 does handle CONNECT for non-HTTP protocols (including
encrypted HTTPS) its involvement is purely that of shuffling bytes
between client and server. So the things to look for there are TCP level
network issues (eg TCP, NAT, or router cache timeouts) closing
connections unexpectedly.
If you have Squid Delay Pools configured that may also be interfering
with connections that need high traffic flow rates.
Check how much traffic Squid is handling at the time(s) these issues
occur. Squid-3.5 has upper limits of around 19K requests/second and ~63K
concurrent client connections (on Linux/BSD, much lower on Windows). If
either of these limits are encountered traffic speeds *will* drastically
reduce speed until the clients adjust to a lower level.
- The fix for these if you actually hit the upper limits is to use
more Squid instances (on different hardware, not VMs on same HW) to
share the traffic load.
- If the speed drop occurs before hitting the limits you can try
optimizing squid.conf settings (ACL sequence in particular), TCP stack
settings (ie. ephemeral ports use and/or TCP flow controls) for performance.
Also check cache.log to see if Squid, workers, or helpers are
halting/crashing at all. These are not very consistent in Squid-3 but
should show up as one or more "FATAL", "ERROR", "assertion failed", or
"unhandled exception", or "halted" messages.
- The fix here is obviously to figure out and prevent the crashes
occuring. Each log message and ones above it should provide some hints
to help with troubleshooting.
FWIW, Squid-3.5 is long out of support and AFAIK CentOS 6 is also.
HTH
Amos
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