I'm using DBCP data source (with default configuration) in Spring configuration to manage my connections to the database, and I'm running into a deadlock condition when the number of clients increase.
I found that there is a deadlock issue in DBCP 1.2.1 which I was using, which was supposed to be resolved in 1.4. So I upgraded to 1.4, but the issue still persists.
In the thread dump, there are many threads blocked with the following stack trace on top:
java.lang.Thread.State: WAITING on org.apache.commons.pool.impl.GenericObjectPool$Latch@b6b09e
at java.lang.Object.wait(Native Method)
at java.lang.Object.wait(Object.java:485)
at org.apache.commons.pool.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:1104)
at org.apache.commons.dbcp.PoolingDataSource.getConnection(PoolingDataSource.java:106)
at org.apache.commons.dbcp.BasicDataSource.getConnection(BasicDataSource.java:1044)
at org.springframework.jdbc.datasource.DataSourceTransactionManager.doBegin(DataSourceTransactionManager.java:200)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:350)
at org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:261)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:101)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:160)
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:89)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
at org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.intercept(Cglib2AopProxy.java:631)
Any suggestions are welcome!
Tomcat DBCP is just a renamed version of Apache Commons DBCP, with also a different internal package name prefix. At build time, Tomcat fetches the Commons DBCP sources (the version depends on the Tomcat version, for instance Tomcat 7.0. 27 uses Commons DBCP 1.4), and does package name replacement ( org.
This Commons package provides an opportunity to coordinate the efforts required to create and maintain an efficient, feature-rich package under the ASF license. The commons-dbcp2 artifact relies on code in the commons-pool2 artifact to provide the underlying object pool mechanisms.
Tomcat jdbc pool implements the ability retrieve a connection asynchronously, without adding additional threads to the library itself. Tomcat jdbc pool is a Tomcat module, it depends on Tomcat JULI, a simplified logging framework used in Tomcat. Retrieve the underlying connection using the javax. sql.
I switched to c3p0, few years back. You can try that. I believe you didn't have to change much, it's just a game of configuration.
Somewhat related thread, Connection pooling options with JDBC: DBCP vs C3P0. Well, actually I made it related.
[edited, 19/10/12]
Tomcat 7 has a decent connection pool, The Tomcat JDBC Connection Pool.
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