Hi Running simple load tests both on Apache directly, and on Varnish - both seem to experience "long delays" on a small percentage of the requests. The problem does not appear to happen with low loads. It does come up as CPU usage becomes an issue. It also is hard to make happen with a single stream of requests. It seems to come up much quicker with many requests done in parallel.
I've always *assumed* that the poor little TCP/IP hamster simply ran out of breath and started dropping connections. Bob -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of George Georgovassilis Sent: Wednesday, January 05, 2011 11:18 AM To: [email protected] Subject: Re: Connections dropped under load Hello Cosimo, Thank you for the quick reply. After your hint I had the tests run again but couldn't detect that pattern. What susprised me though after looking through the logs is that almost all requests by the load generator complete in a timely manner ( < 1 sec), but all requests generated by a real browser (IE, FF, Opera) will be served much later or even run into a timeout. On 05.01.2011 16:30, Cosimo Streppone wrote: > On Wed, 05 Jan 2011 16:20:31 +0100, George Georgovassilis > <[email protected]> wrote: > >> I'm having trouble with dropped connections under a loadtest. >> >> The problem: As a measure for response, I am requesting an image from >> the webapp running in Tomcat while the loadtest is underway. However >> that either times out or is delivered after several seconds. Varnishlog >> will often either not show the request (RxURL) at all, or show it >> several seconds after the browser dispatched it. > > Hi George, > > if you measure the time you mention as "several seconds" > and it's either 3 or 9 seconds, I think what you're seeing > is a client-side TCP retransmit timeout. > > I experienced that, both under load testing, > and in real production setups. > _______________________________________________ varnish-misc mailing list [email protected] http://www.varnish-cache.org/lists/mailman/listinfo/varnish-misc _______________________________________________ varnish-misc mailing list [email protected] http://www.varnish-cache.org/lists/mailman/listinfo/varnish-misc
