I’m facing a frustrating error while getting connection from mysql db. I’m using c3p0 with Spring 3.1 & Hibernate 4..
Any helps will be appreciated a lot! Thanks in advance..
With regards..
Here’s my maven dependencies for pooling:
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-core</artifactId>
<version>${hibernate.version}</version>
</dependency>
<!-- Hibernate c3p0 connection pool -->
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-c3p0</artifactId>
<version>${hibernate.version}</version>
</dependency>
<dependency>
<groupId>org.hibernate.javax.persistence</groupId>
<artifactId>hibernate-jpa-2.0-api</artifactId>
<version>1.0.1.Final</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-entitymanager</artifactId>
<version>${hibernate.version}</version>
</dependency>
Spring Hibernate database config:
<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close">
<property name="driverClass" value="com.mysql.jdbc.Driver" />
<property name="jdbcUrl" value="jdbc:mysql://localhost:3306/ext4playground" />
<property name="user" value="xx" />
<property name="password" value="xx" />
<property name="maxPoolSize" value="10" />
<property name="initialPoolSize" value="3" />
<property name="maxStatements" value="50" />
<property name="minPoolSize" value="3" />
<property name="idleConnectionTestPeriod" value="100" />
<property name="maxIdleTime" value="200" />
<property name="acquireIncrement" value="1" />
</bean>
<!-- Hibernate SessionFactory -->
<bean id="sessionFactory" class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
<property name="dataSource"><ref local="dataSource"/></property>
<property name="packagesToScan" value="com.tk.sample.ext4.model" />
<property name="hibernateProperties">
<props>
<prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop>
<prop key="hibernate.show_sql">true</prop>
<prop key="hibernate.use_sql_comments">true</prop>
<prop key="hibernate.format_sql">false</prop>
<prop key="hibernate.hbm2ddl.auto">update</prop>
<prop key="hibernate.generate_statistics">true</prop>
<prop key="hibernate.connection.characterEncoding">UTF-8</prop>
<prop key="hibernate.connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider</prop>
<!-- c3p0 properties -->
<prop key="hibernate.c3p0.min_size">2</prop>
<prop key="hibernate.c3p0.max_size">50</prop>
<prop key="hibernate.c3p0.timeout">300</prop>
<prop key="hibernate.c3p0.max_statements">50</prop>
<prop key="hibernate.c3p0.idle_test_period">3000</prop>
<prop key="hibernate.c3p0.acquireRetryAttempts">30</prop>
<prop key="hibernate.c3p0.acquireIncrement">5</prop>
<prop key="hibernate.c3p0.initialPoolSize">2</prop>
<prop key="hibernate.c3p0.maxPoolSize">50</prop>
<prop key="hibernate.c3p0.maxIdleTime">300</prop>
<prop key="hibernate.c3p0.maxStatements">50</prop>
<prop key="hibernate.c3p0.minPoolSize">2</prop>
<prop key="hibernate.c3p0.preferredTestQuery">SELECT 1;</prop>
<prop key="hibernate.c3p0.testConnectionOnCheckout">true</prop>
</props>
</property>
</bean>
<!-- Transaction manager for a single Hibernate SessionFactory (alternative to JTA) -->
<tx:annotation-driven/>
<bean id="transactionManager" class="org.springframework.orm.hibernate4.HibernateTransactionManager">
<property name="sessionFactory"><ref local="sessionFactory"/></property>
</bean>
Full stacktrace:
org.springframework.transaction.CannotCreateTransactionException: **Could not open Hibernate Session for transaction**; nested exception is org.hibernate.exception.GenericJDBCException: **Could not open connection**
at org.springframework.orm.hibernate4.HibernateTransactionManager.doBegin(HibernateTransactionManager.java:440)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:371)
at org.springframework.test.context.transaction.TransactionalTestExecutionListener$TransactionContext.startTransaction(TransactionalTestExecutionListener.java:513)
at org.springframework.test.context.transaction.TransactionalTestExecutionListener.startNewTransaction(TransactionalTestExecutionListener.java:271)
at org.springframework.test.context.transaction.TransactionalTestExecutionListener.beforeTestMethod(TransactionalTestExecutionListener.java:164)
at org.springframework.test.context.TestContextManager.beforeTestMethod(TestContextManager.java:358)
at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:73)
at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:83)
at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:72)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:231)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:49)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:71)
at org.junit.runners.ParentRunner.run(ParentRunner.java:236)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:174)
at org.junit.runner.JUnitCore.run(JUnitCore.java:157)
at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:63)
Caused by: org.hibernate.exception.GenericJDBCException: Could not open connection
at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:54)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:125)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:110)
at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.obtainConnection(LogicalConnectionImpl.java:304)
at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.getConnection(LogicalConnectionImpl.java:169)
at org.hibernate.engine.transaction.internal.jdbc.JdbcTransaction.doBegin(JdbcTransaction.java:67)
at org.hibernate.engine.transaction.spi.AbstractTransactionImpl.begin(AbstractTransactionImpl.java:160)
at org.hibernate.internal.SessionImpl.beginTransaction(SessionImpl.java:1309)
at org.springframework.orm.hibernate4.HibernateTransactionManager.doBegin(HibernateTransactionManager.java:399)
... 23 more
Caused by: java.sql.SQLException: Connections could not be acquired from the underlying database!
at com.mchange.v2.sql.SqlUtils.toSQLException(SqlUtils.java:106)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:529)
at com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.getConnection(AbstractPoolBackedDataSource.java:128)
at org.hibernate.service.jdbc.connections.internal.C3P0ConnectionProvider.getConnection(C3P0ConnectionProvider.java:79)
at org.hibernate.internal.AbstractSessionImpl$NonContextualJdbcConnectionAccess.obtainConnection(AbstractSessionImpl.java:279)
at org.hibernate.engine.jdbc.internal.LogicalConnectionImpl.obtainConnection(LogicalConnectionImpl.java:297)
... 28 more
Caused by: com.mchange.v2.resourcepool.CannotAcquireResourceException: A ResourcePool could not acquire a resource from its primary factory or source.
at com.mchange.v2.resourcepool.BasicResourcePool.awaitAvailable(BasicResourcePool.java:1319)
at com.mchange.v2.resourcepool.BasicResourcePool.prelimCheckoutResource(BasicResourcePool.java:557)
at com.mchange.v2.resourcepool.BasicResourcePool.checkoutResource(BasicResourcePool.java:477)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool.checkoutPooledConnection(C3P0PooledConnectionPool.java:525)
... 32 more
Please check your logs. Prior to the Exception that you have shown above, c3p0 would have logged stack traces detailing the pools failed attempt to acquire Connections from the database. If you set the logging level to FINE (if you want a specific logger, use com.mchange.v2.resourcepool.BasicResourcePool), you’ll see each failed attempt logged. If you leave your log level at the conventional INFO (or WARN), you’ll see only the final failed attempt in a “round” of failed attempts (by default 30 failed attempts with a 1 sec retry delay). If you’ve been logging at INFO, you should be able to find these Exceptions in your logs already.
Note in your config, you’ve defined some c3p0 config parameters as many as three times, and sometimes inconsistently. This is not the cause of your problem here, but it’s a bit inelegant and leaves some uncertainty about which value will actually take. For example, maxPoolSize, hibernate.c3p0.max_size, and hibernate.c3p0.maxPoolSize all trickle down the the same c3p0 parameter. If you want to see which value is actually being set, check your logs (at INFO) for the config dump c3p0 pools generate on initialization.