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From Niall Gallagher <>
Subject DBCP connection pool problem
Date Fri, 19 Jan 2007 10:36:08 GMT
Hi All,

I am using the latest commons DBCP library (1.2.1) as our connection 
pooling solution for an Oracle DB. However I am encountering a strange 
issue where under certain conditions DBCP seems to open an excessive 
amount of connections to the DB. We are not sure exactly what is causing 
the problem but we suspect that it is the Evictor task within the 
commons-pool library.

When the issue occurs the TNS listener logs for Oracle show an massive 
growth in the number of connections being attempted. For instance here 
is the activity over a couple of minutes.

03-JAN-2007, 16:48, db1,, 52858
03-JAN-2007, 16:49, db1,, 61696
03-JAN-2007, 16:50, db1,, 61107
03-JAN-2007, 16:51, db1,, 61475
03-JAN-2007, 16:52, db1,, 61446

On average about 60,000 connections a minute. We are quite certain this 
is caused by DBCP as this is the only means of accessing DB connections 
within our applications and we log before and after the 
DataSource.getConnection method (our logs show no repetitive log 
statements).  Has anyone seen such an issue before? Any help on this 
would be greatly appreciated.


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