MySQL seems to have an 8 hour time out on its connections. I'm running multiple WARs in Tomcat utilizing Hibernate for ORM. After 8 hours (i.e. overnight), I get broken pipes when it picks up an idle connection.
I've already traced through the code and made doubly sure I commit or rollback all transactions.
Here is my hibernate.cfg.xml
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<property name="hibernate.bytecode.use_reflection_optimizer">false</property>
<property name="hibernate.connection.driver_class">org.gjt.mm.mysql.Driver</property>
<property name="hibernate.connection.password"></property>
<property name="hibernate.connection.url">jdbc:mysql://localhost/test</property>
<property name="hibernate.connection.username">root</property>
<property name="hibernate.dialect">org.hibernate.dialect.MySQL5InnoDBDialect</property>
<property name="hibernate.transaction.factory_class">org.hibernate.transaction.JDBCTransactionFactory</property>
<property name="hibernate.current_session_context_class">thread</property>
<!--property name="hibernate.show_sql">true</property>
<property name="hibernate.format_sql">true</property-->
<property name="c3p0.min_size">3</property>
<property name="c3p0.max_size">5</property>
<property name="c3p0.timeout">1800</property>
<property name="c3p0.preferredTestQuery">SELECT 1</property>
<property name="c3p0.testConnectionOnCheckout">true</property>
<property name="c3p0.idle_test_period">100</property> <!-- seconds -->
<property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>
<property name="cache.use_query_cache">false</property>
<property name="cache.use_minimal_puts">false</property>
<property name="max_fetch_depth">10</property>
<property name="hibernate.hbm2ddl.auto">update</property>
<!-- classes removed -->
</session-factory>
The parameter I thought would have fixed it was the c3p0.idle_test_period
-- It defaults to 0. However, we still have the Broken Pipe issue after 8 hours of running. While there are multiple posts index via Google, none arrive at a satisfactory answer.
So it turns out I was missing a key line that enabled c3p0 (the c3p0 parameters I was tweaking were having no effect because Hibernate was using it's built in connection pool -- which it appropriately warns is not suitable for production). In hibernate 2.x, setting the hibernate.c3p0.max_size
property enabled c3p0 connection pooling. However, in 3.x you must specify the following property --
<property name="hibernate.connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider</property>
Additionally, here are my final configuration parameters --
<property name="hibernate.c3p0.min_size">3</property>
<property name="hibernate.c3p0.max_size">5</property>
<property name="hibernate.c3p0.timeout">1800</property>
<property name="hibernate.c3p0.idle_test_period">100</property> <!-- seconds -->
It's rather unfortunate that both Hibernate and c3p0 have abysmal documentation in this regard.
There are two things going on here. You should read this article for more details, but the take-aways are:
hibernate.c3p0.idle_test_period
instead of just c3p0.idle_test_period
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