Hello,
I am experiencing the following exception with C3p0:

24 Feb 2006 17:22:00,611 WARN BasicResourcePool.run:638 - Failed to destroy resource: com.mchange.v2.c3p0.impl.NewPooledConnection@191a42
java.lang.NullPointerException
at com.mysql.jdbc.Statement.close(Statement.java:808)
at com.mysql.jdbc.Connection.closeAllOpenStatements(Connection.java:2541)
at com.mysql.jdbc.Connection.close(Connection.java:1067)
at com.mchange.v2.c3p0.impl.NewPooledConnection.close(NewPooledConnection.java:405)
at com.mchange.v2.c3p0.impl.NewPooledConnection.close(NewPooledConnection.java:135)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1.destroyResource(C3P0PooledConnectionPool.java:208)
at com.mchange.v2.resourcepool.BasicResourcePool$5.run(BasicResourcePool.java:634)
at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:368)

C3P0 Configuration:

<property name="connection.provider_class">net.sf.hibernate.connection.C3P0ConnectionProvider</property>
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="connection.url">jdbc:mysql://localhost/db</property>
<property name="connection.username">someuser</property>
<property name="connection.password">*****</property>
<property name="connection.autoReconnect">true</property>
<property name="connection.autoReconnectForPools">true</property>
<property name="connection.is-connection-validation-required">true</property>

<!-- c3p0 configuration -->
<property name="c3p0.acquire_increment">1</property>
<property name="c3p0.idle_test_period">100</property> <!-- seconds -->
<property name="c3p0.max_size">100</property>
<property name="c3p0.max_statements">0</property>
<property name="c3p0.min_size">10</property>
<property name="c3p0.timeout">100</property> <!-- seconds -->
<property name="c3p0.validate">true</property>

Hibernate version is 2.1.8, and c3p0 version is 0.9.0
Running on tomcat 5.0.3 with jdk1.4.2.
C3p0 version .8.4.5 is working fine.
Any suggestions greatly appreciated
Thank you,
Roman

Now there is a deadlock occuring every few days...
Hibernate v 2.1.8 with MySQL 4.0.26 running on tomcat 5.0.28, c3p0 .9.04

Hibernate.cfg.xml:
<!-- Maximum size of C3P0 connection pool -->
<!-- Maximum size of C3P0 statement cache -->
<!-- Number of connections acquired when C3P0 pool is exhausted -->
<!-- Idle time (seconds) before a C3P0 pooled connection is validated -->
<!-- Maximum idle time (seconds) for a C3P0 connection pool -->
<property name="c3p0.min_size">5</property>
<property name="c3p0.max_size">25</property>
<property name="c3p0.timeout">1800</property>
<property name="c3p0.max_statements">0</property>
<property name="c3p0.acquire_increment">3</property>
<property name="c3p0.validate">true</property>
<property name="c3p0.idle_test_period">180</property>

c3p0.properties:
c3p0.acquireRetryDelay=1000
c3p0.acquireRetryAttempts=60
c3p0.breakAfterAcquireFailure=false
c3p0.preferredTestQuery=SELECT 1
c3p0.testConnectionOnCheckin=true
c3p0.testConnectionOnCheckout=true


01 Mar 2006 15:49:49,165 WARN ThreadPoolAsynchronousRunner.run:435 - com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@1cfe3 -- APPARENT DEADLOCK!!! Complete Status: [num_managed_threads: 3, num_active: 3; activeTasks: com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@8627c3 (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#0), com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@19c9d88 (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#1), com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@12a7fd6 (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#2); pendingTasks: com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@12ec15a, com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@982d8e]
01 Mar 2006 15:50:49,996 WARN ThreadPoolAsynchronousRunner.processReplacedThreads:281 - Task com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@8627c3 (in deadlocked PoolThread) failed to complete in maximum time 60000ms. Trying interrupt().