[c3p0-users] JDBCConnectionException: Communications link failure event if I use c3p0 pooling

[Marc S. <mar...@gm...>]

Hi,

I get a quite well-known using MySql jdbc driver :
JDBCConnectionException: Communications link failure,
java.io.EOFException: Can not read response from server. This is
caused by the wait_timeout parameter in my.cnf. So I decided to use
c3p0 pool connection along with Hibernate. Here is what I added to
hibernate.cfg.xml :

<property name="hibernate.connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider</property>
<property name="hibernate.c3p0.min_size">10</property>
<property name="hibernate.c3p0.max_size">100</property>
<property name="hibernate.c3p0.timeout">1000</property>
<property name="hibernate.c3p0.preferredTestQuery">SELECT 1</property>
<property name="hibernate.c3p0.acquire_increment">1</property>
<property name="hibernate.c3p0.idle_test_period">2</property>
<property name="hibernate.c3p0.max_statements">50</property>

idle_test_period is volontarily low for test purposes. Looking at the
mysql logs I can see the "SELECT 1" query which is regularly sent to
the mysql server so it works. Unfortunately I still get this EOF
exception within my app if I wait longer than 'wait_timout' seconds
(set to 10 for test purposes).

I'm using Hibernate 4.1.1 and mysql-jdbc-connector 5.1.18 and hibernate-c3p0

So what am I doing wrong? How could I debug this?

Thanks, Marc.