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From Ravi116 <>
Subject Re: DBCP connection pool problem
Date Tue, 29 May 2007 22:10:01 GMT

This dosent seem to be my problem since the evictor threads runs every 30
mins (default) and evicts 3 connections. The condition in my case is
connections are created in large chunks (30+) rather than incrementally.
Below are my connection parameters  - 

        <property name="initialSize" value="2" />
        <property name="poolPreparedStatements" value="true" />
        <property name="maxOpenPreparedStatements" value="3" />
        <property name="minIdle" value="2" />
        <property name="maxIdle" value="-1" />
        <property name="maxActive" value="200" />
        <property name="testWhileIdle" value="true" />
        <property name="testOnBorrow" value="false" />     
        <property name="timeBetweenEvictionRunsMillis" value="1800000" />
        <property name="validationQuery"
            value="select 1 from sysibm/sysdummy1 for read only" />

Tomcat and SpringJDBC is used. After tracing with log statements, it seems
to be like borrowObject() on GenericPoolObject is making all the
connections.  From the last run, the connection were added in batches  
Initial size - 2 (bfore test started)
Increased number of connections - 29 (~2 mins into the test)
Increased number of connections - 151 (~10 mins into the test).

This test is run on IBM AIX JDK version 1.5.X.

Any help is appreciated,


Niall Gallagher-3 wrote:
> 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.
> Thanks,
> Niall
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