In meinem Tomcat-Protokoll wird immer wieder die folgende Ausnahme angezeigt:

com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector run
WARNING: com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@76b28200 -- APPARENT DEADLOCK!!! Creating emergency threads for unassigned pending tasks!
com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector run
WARNING: com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@76b28200 -- APPARENT DEADLOCK!!! Complete Status: 
    Managed Threads: 3
    Active Threads: 3
    Active Tasks: 
        com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@1201fd18 (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#1)
        com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@408f3be4 (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#0)
        com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@7ba516d8 (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#2)
    Pending Tasks: 
        com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@137efe53
        com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@766b0524
Pool thread stack traces:
    Thread[com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#1,5,main]
        java.lang.Thread.sleep(Native Method)
        com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask.run(BasicResourcePool.java:1805)
        com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)
    Thread[com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#0,5,main]
        java.lang.Thread.sleep(Native Method)
        com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask.run(BasicResourcePool.java:1805)
        com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)
    Thread[com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#2,5,main]
        java.lang.Thread.sleep(Native Method)
        com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask.run(BasicResourcePool.java:1805)
        com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)

Ich verwende Hibernate 3.6.2 und C3P0 0.9.1.2 mit MySQL. Nach einigen Stunden der Suche in Google scheint diese APPARENT DEADLOCK-Ausnahme normalerweise mit der Zwischenspeicherung vorbereiteter Anweisungen verbunden zu sein. Dies ist meine C3P0-Konfiguration in meiner hibernate.cfg.xml:

<propertyname="connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider</property>
<property name="hibernate.c3p0.acquire_increment">5</property>
<property name="hibernate.c3p0.min_size">5</property>
<property name="hibernate.c3p0.max_size">60</property>
<property name="hibernate.c3p0.idle_test_period">120</property>
<property name="hibernate.c3p0.timeout">180</property>              
<property name="hibernate.c3p0.max_statements">0</property>

Ich tue keine Aussage, die überhaupt cacht. Irgendwelche Hinweise darauf, was hier falsch ist, wären sehr dankbar.