resume for XID raised 0: unknown - mysql

Question

I am using Spring 3.0.5, Hibernate 3.6.7, Atomikos TransactionEssentials 3.7.0 and MySQL 5.5
I recently faced the problem, that connections in my connectionpool timedout after 8 hours and were reset by the server causing a message "resume for XID '???' raised 0: unknown
Here is my datasource configuration:
<bean id="myDataSource"
class="com.atomikos.jdbc.AtomikosDataSourceBean"
init-method="init"
destroy-method="close"
depends-on="myConfigurer">
<property name="uniqueResourceName" value="myPUDataSource" />
<property name="xaDataSourceClassName" value="$CONF{database.XAdriver}" />
<property name="poolSize" value="10" />
<property name="xaProperties">
<props>
<prop key="user">$CONF{database.user}</prop>
<prop key="password">$CONF{database.password}</prop>
<prop key="URL">$CONF{database.url}</prop>
<prop key="pinGlobalTxToPhysicalConnection">true</prop>
<prop key="autoReconnect">true</prop>
</props>
</property>
</bean>
As I was investigating I found out that the option autoReconnect=true only reconnects my faulted connection after a delay of 2 seconds (which is configurabe I think).
Browsing the web I found solutions suggesting to increase wait_timeout in the MySQL-Server, which I think is not a real solution.
The application should be able to handle dead connections and reconnect automatically, because there may be other issues causing a connection loss, too.
(And I don't want to make any directives to Servers whatever kind the application uses).
At last I found a good solution for this, which I will post as answer to help people facing the same or similar problems.

Answer 1

By inserting the line:
<property name="testQuery" value="SELECT 1"/>
on the data source's configuration, it seems the connection is tested before use and reconnected if it's dead.
I tried it with wait_timeout=60 and even with a restart of the MySQL-Server while my application was running...
Result: no more Exceptions and Errors!