Connections dropped under load

George Georgovassilis g.georgovassilis at
Wed Jan 5 17:17:57 CET 2011

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 
> <g.georgovassilis at> 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.

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