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From Peter Beichert <>
Subject Re: limit number of connections tomcat accepts
Date Fri, 08 Jan 2010 08:02:48 GMT
Thank you for your help. The good new is, that Tomcat really works like it 
supposed to. The problem is, that the operating system holds all the 
connections which did not receive an acknowledgement from the server.

When monitoring the tcp-connections during the tests with netstat, I could 
see, that the number of established connections was the sum of threads plus 
the number of queued requests. All other connections could be observed at the 
server with a SYN_RECV state. As soon as tomcat finished one request, a new 
connection was acknowledged and the number of connections with the SYN_RECV 
state decreased by one.

The value of the maximum remembered connection requests in Linux is the Kernel 
parameter tcp_max_syn_backlog which is by default 1024. It can be reduced with 
the /sbin/sysctl command.

best regards
Am Mittwoch, 6. Januar 2010 14:50:18 schrieb Christopher Schultz:
> Peter,
> On 1/6/2010 3:03 AM, Peter Beichert wrote:
> > If I start 100 parallel requests to a servlet which does nothing else
> > than waiting 5 seconds, I would expect that only 8 requests would be
> > accepted, the rest should receive a connection refused.
> A lot here depends upon the behavior of the client. Some clients will
> try until they get a connection rather than giving up. Is this how you
> have configured JMeter and/or wget?
> -chris
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