[FIXED] Hibernate - Is there a possibility to wait with createEntityManager for a free connection

Issue

I'm using the EntityManagerFactory from Hibernate and have a connectionPoolSize of 20. Now I have some larger queries (t> 30 min) that take up my pool completely. When I start a new query (with getEntityManager) I get the following exception:

javax.persistence.PersistenceException: org.hibernate.HibernateException: 
The internal connection pool has reached its maximum size and no connection is currently available!
at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:154)
at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:181)
at org.hibernate.query.internal.AbstractProducedQuery.list(AbstractProducedQuery.java:1538)
at org.hibernate.query.Query.getResultList(Query.java:165)

Are there any comfort features that put my thread to sleep until a connection is available?

I only use standard functions:

public static EntityManager getEntityManager () {
return emFactory.createEntityManager ();
}

The Creation of my EntityManagerFactory:

public static void createEntityManagerFactory(String hostname, Integer port, String driver,
  String database, boolean validate, int maxConnections, Properties properties) {

Properties props = new Properties();
props.setProperty("hibernate.connection.url", "jdbc:" + driver + ":thin:@" + hostname + ":" + port + ":" + database);
props.setProperty("hibernate.connection.driver_class", "oracle.jdbc.driver.OracleDriver");
props.setProperty("hibernate.connection.username", properties.getProperty("user")); 
props.setProperty("hibernate.connection.password", properties.getProperty("password"));
props.setProperty("hibernate.dialect", "org.hibernate.dialect.Oracle10gDialect");

emFactory = Persistence.createEntityManagerFactory(PERSISTENCE_UNIT_NAME, props);

}

My persistence.xml contains:

<property name="connection.pool_size" value="20" />

I read about C3P0 settings, could they help me?

-- UPDATE -- I had some problems with C3P0 (for example: ORA-01652: unable to extend temp segment by 128 in tablespace SYSTEM even with a small number of maximum connection pool size), that I didnt have with hibernate vanilla. -- Configuration c3p0

<property name="hibernate.c3p0.min_size" value ="2"/> 
<property name="hibernate.c3p0.max_size" value ="10"/> 
<property name="hibernate.c3p0.acquire_increment" value ="2"/> 
<property name="hibernate.c3p0.idle_test_period" value ="100"/> 
<property name="hibernate.c3p0.timeout" value ="3600"/>

Solution

Ive solved this problem with using hikaricp for connection pooling.

Answered By - MavidDeyers
Answer Checked By - Robin (JavaFixing Admin)