[squid-users] Occasional slow connections/timeouts

I've got a problem at the moment with our general squid proxies where
occasionally requests take a long time that shouldn't do. (i.e. 5+ seconds
or timeout, instead of milliseconds).

This is most common on our proxies doing 100 reqs/sec, but happens
overnight too when they're running at 10 reqs/sec. I've got this happening
with both v3.4.2 and also with a box I've downgraded back to v3.1.10. For
v3.4.2, it's happening in both multiple worker and single worker modes.

The test is not reproducible, sadly, but I've got a cronjob running on
localhost on these boxes testing access times to various URLs covering:
HTTPS, non-HTTPS static content, using IP not hostname over both HTTP and
HTTPS, and a URL on the same vlan as the proxies. All of these test cases
have it happen occasionally, but not repeatedly/reliably.

Different boxes are either running Trend's IWSVA for it's antivirus as a
cache_peer, or C-ICAP/clamd as an ICAP service. These both have it happen
(as does the case where I disabled the antivirus).

The servers are all running CentOS6.4 on HP Gen8 blades with 48G RAM.

Has anyone seen anything like this, or got any suggestions as to what
might be causing this that I can investigate further?

Simon
Received on Thu Feb 20 2014 - 17:10:54 MST