Try to run app without pool first to find broken component. Most of
Connection leak problems are in applications and it is not easy to trust
this test.
----- Original Message -----
From: "Todd Carmichael" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Monday, October 27, 2003 7:32 PM
Subject: [dbcp] Trying to track/find a connection leak in DBCP 1.1
> Our scalability tests against our web application (350 concurrent users in
a
> web application using Tomcat 4.1.24 with JDK 1.4.2) is failing due to a
> continual leak of database connections. The test failed in that the
number
> of database connections (reported by the DB server: MS SQL Server) grew to
> over a thousand during an hour plus test (using the microsoft sql jdbc
> driver though we have tried the i-net driver with similar results). We
know
> that it is not a problem in the application because we have performed
> identical tests except to configure Torque to use the
JndiDatasourceFactory.
> This in passes the connection pooling chores to the appserver. Both
SunOne
> appserver and Weblogic appserver maintained a valid number of connections
(<
> 75). We are using Torque 3.1 with DBCP 1.1 (using the
> org.apache.commons.dbcp.datasources.SharedPoolDataSource) and Pool 1.1.
>
> Our settings in our torque.properties (which can passed down to the
> SHaredPoolDataSource) are:
>
> torque.dsfactory.default.pool.maxActive=100
> torque.dsfactory.default.pool.testOnBorrow=0
> torque.dsfactory.default.pool.testOnReturn=0
> #no setting for maxIdle. It defaults to 8. Not optimal but code should
> still work:
> torque.dsfactory.default.pool.timeBetweenEvictionRunsMillis=60000
> torque.dsfactory.default.pool.numTestsPerEvictionRun=-1
> torque.dsfactory.default.pool.minEvictableIdleTimeMillis=1000
> torque.dsfactory.default.pool.testWhileIdle=false
>
> I have begun some debugging of this problem. I have added some debug
output
> in the torqueInstance.getConnection to track size of the pool.
>
> iCountConnections++;
> if ((iCountConnections % 100)==0)
> {
> SharedPoolDataSource spds =
> (SharedPoolDataSource)dsf.getDataSource();
> log.warn("Current Num Active Connections=" +
> String.valueOf(spds.getNumActive()));
> log.warn("Current Num Idle Connections=" +
> String.valueOf(spds.getNumIdle()));
> log.warn("Max Active =" +
> String.valueOf(spds.getMaxActive()));
> log.warn("Max Idle =" +
String.valueOf(spds.getMaxIdle()));
> log.warn("Max Wait =" +
String.valueOf(spds.getMaxWait()));
> }
>
> Here is a sample of the output when I run our scalability tests. At this
> point the system is under heavy load and the db server is reporting over
100
> connections:
>
> [WARN] TorqueInstance - -Current Num Active Connections=3
> [WARN] TorqueInstance - -Current Num Idle Connections=5
> [WARN] TorqueInstance - -Max Active =100
> [WARN] TorqueInstance - -Max Idle =8
> [WARN] TorqueInstance - -Max Wait =500
> [WARN] TorqueInstance - -Current Num Active Connections=5
> [WARN] TorqueInstance - -Current Num Idle Connections=3
> [WARN] TorqueInstance - -Max Active =100
> [WARN] TorqueInstance - -Max Idle =8
> [WARN] TorqueInstance - -Max Wait =500
> [WARN] TorqueInstance - -Current Num Active Connections=19
> [WARN] TorqueInstance - -Current Num Idle Connections=0
> [WARN] TorqueInstance - -Max Active =100
> [WARN] TorqueInstance - -Max Idle =8
> [WARN] TorqueInstance - -Max Wait =500
> [WARN] TorqueInstance - -Current Num Active Connections=32
> [WARN] TorqueInstance - -Current Num Idle Connections=0
> [WARN] TorqueInstance - -Max Active =100
> [WARN] TorqueInstance - -Max Idle =8
> [WARN] TorqueInstance - -Max Wait =500
> [WARN] TorqueInstance - -Current Num Active Connections=39
> [WARN] TorqueInstance - -Current Num Idle Connections=1
> [WARN] TorqueInstance - -Max Active =100
> [WARN] TorqueInstance - -Max Idle =8
> [WARN] TorqueInstance - -Max Wait =500
> [WARN] TorqueInstance - -Current Num Active Connections=40
> [WARN] TorqueInstance - -Current Num Idle Connections=0
> [WARN] TorqueInstance - -Max Active =100
> [WARN] TorqueInstance - -Max Idle =8
> [WARN] TorqueInstance - -Max Wait =500
> [WARN] TorqueInstance - -Current Num Active Connections=39
> [WARN] TorqueInstance - -Current Num Idle Connections=2
> [WARN] TorqueInstance - -Max Active =100
> [WARN] TorqueInstance - -Max Idle =8
> [WARN] TorqueInstance - -Max Wait =500
>
> As you can see, the number of connections reported by the pool is not even
> close to the number connections reported by the database.
> ToddC
>
> Also we are getting an exception during the test:
> java.sql.SQLException: Attempted to use Connection after closed() was
> called.
> at
>
org.apache.commons.dbcp.cpdsadapter.ConnectionImpl.assertOpen(ConnectionImpl
> .java:140)
> at
>
org.apache.commons.dbcp.cpdsadapter.ConnectionImpl.getMetaData(ConnectionImp
> l.java:253)
> at org.apache.torque.util.Transaction.rollback(Transaction.java:193)
> at
> org.apache.torque.util.Transaction.safeRollback(Transaction.java:232)
> at com.concur.om.base.BaseCtReportEntry.save(Unknown Source)
>
> After this exception occurs, I receive no more output as shown above. The
> system appears deadlocked. I can send a stack dump (Ctrl-Break on Wintel
> machines). The stack dump is pretty interesting as it shows where the
> contention is within dbcp and pool system but I don't know if it will help
> debug this leak problem (e.g. only one thread can create a db connection
at
> time because the connection to the db is created during makeobject). Let
me
> know if anyone is interested in seeing the dump.
>
> This problem is critical for us (I had advocated moving to new Torque and
> DBCP and now am in a tough spot with this problem). I will continue to
> debug what I can and can apply patches fairly easily and run them.
>
> Thanks for any timely help
> Todd Carmichael
>
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