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From jgelb <>
Subject DBCP maxActive does not set limit?
Date Fri, 08 Apr 2005 15:39:55 GMT

Sorry if this is the wrong place -- I tried to check the archives first 
and get the faq and info from the list itself, but none of that was 
working, and I'm not finding anything via google (yet).

I'm seeing something that I don't understand when using DBCP in Tomcat 
(5.0.27 and 5.0.28) and I was wondering if anyone familiar with the code 
might be able to enlighten me.

Specifically, during load tests netstat is showing me that I have more 
TCP connections in ESTABLISHED state than my maxActive settings -- 
sometimes -many- more.

In one test contrived to excercise the pool and nothing else, I set 
maxActive to 50 and then ran through 20000 requests (70 simultaneous 
requestors).  At one point I saw 198 connections to my database.

I understand that network connectivity doesn't necessarily correlate 
directly to a database connection, but if the pool really is limiting 
itself to maxActive connections, I don't understand why I'd ever see 
more than maxActive established network connections.

Fwiw, observations were on redhat linux ES 3 (using 2.4.21 kernel?) and 
a gentoo linux build using a 2.6.9 kernel, using oracle and postgres as 
the backends.

Any insight or comments much appreciated.

-- jeff gelb

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