Hi, We have a multi threaded environment. We have noticed that thread blocks for 10 to 20 minutes due DBCP getConnection method call. Then, we investigated the source code of DBCP(commons-dbcp-1.2.1-PII.jar) and noticed that createConnection method is synchronized. This problem occur more frequently when we have lower value of MaxIdleConnection parameter. After increasing the value of MaxIdleConnection parameter, frequency of blocking get reduced. We then replaced DBCP connection pooling with Oracle Connection pooling (ojdbc14.jar) and never encountered blocking issue.
I think the issue is with that createConnection method of DBCP synchronization. We have taken Thread dump to do above analysis. On Mon, Jun 22, 2009 at 4:33 PM, Eric B. <ebe...@hotmail.com> wrote: > Hi, > > I appologize in advance for the cross-post, but I'm really not sure if this > is a problem with the dbcp code or my configuration. > > I ran into the most troublesome deadlock over the weekend on my server, and > cannot figure out how/or why this deadlock occured. Via jconsole, I was > able to get thread information of the deadlock, but that hasn't helped me > diagnose the problem any further and/or determine if it is a config error, > or something more critical in the tomcat pool. > > From what I can tell, there is a race condition where the evictor was > triggered at the exact same moment as a resource was being added back into > the pool. The evictor was waiting for the resource to be added to the > pool, > and the resource was waiting for the evictor to finish. However, I'm not > sure if I am correct or not. > > > My jndi settings are as follows: > <!-- Database resource --> > <Resource name="jdbc/db" auth="Container" > type="javax.sql.DataSource" username="db" password="db" > driverClassName="com.mysql.jdbc.Driver" > url="jdbc:mysql://localhost:3306/myapp?autoReconnect=true" > maxActive="100" maxIdle="4" > validationQuery="select 1" > testOnBorrow="true" > testWhileIdle="true" > timeBetweenEvictionRunsMillis="10000" > minEvictableIdleTimeMillis="60000" /> > > > My thread trace is the following: > THREAD 1: > Name: Timer-1 > State: BLOCKED on org.apache.tomcat.dbcp.dbcp.poolableconnect...@1e667871 > owned by: scheduling.QuartzInternal_Worker-0 > Total blocked: 1 Total waited: 15,342 > > Stack trace: > > org.apache.tomcat.dbcp.dbcp.AbandonedTrace.addTrace(AbandonedTrace.java:175) > org.apache.tomcat.dbcp.dbcp.AbandonedTrace.init(AbandonedTrace.java:92) > org.apache.tomcat.dbcp.dbcp.AbandonedTrace.<init>(AbandonedTrace.java:82) > > org.apache.tomcat.dbcp.dbcp.DelegatingStatement.<init>(DelegatingStatement.java:61) > > org.apache.tomcat.dbcp.dbcp.DelegatingConnection.createStatement(DelegatingConnection.java:224) > > org.apache.tomcat.dbcp.dbcp.PoolableConnectionFactory.validateConnection(PoolableConnectionFactory.java:331) > > org.apache.tomcat.dbcp.dbcp.PoolableConnectionFactory.validateObject(PoolableConnectionFactory.java:312) > > org.apache.tomcat.dbcp.pool.impl.GenericObjectPool.evict(GenericObjectPool.java:1217) > - locked org.apache.tomcat.dbcp.pool.impl.genericobjectp...@741a266 > > org.apache.tomcat.dbcp.pool.impl.GenericObjectPool$Evictor.run(GenericObjectPool.java:1341) > java.util.TimerThread.mainLoop(Unknown Source) > java.util.TimerThread.run(Unknown Source) > > > THREAD 2: > Name: scheduling.QuartzInternal_Worker-0 > State: BLOCKED on > org.apache.tomcat.dbcp.pool.impl.genericobjectp...@741a266 > owned by: Timer-1 > Total blocked: 156,031 Total waited: 206,465 > > Stack trace: > > org.apache.tomcat.dbcp.pool.impl.GenericObjectPool.addObjectToPool(GenericObjectPool.java:1137) > > org.apache.tomcat.dbcp.pool.impl.GenericObjectPool.returnObject(GenericObjectPool.java:1076) > > org.apache.tomcat.dbcp.dbcp.PoolableConnection.close(PoolableConnection.java:87) > - locked org.apache.tomcat.dbcp.dbcp.poolableconnect...@1e667871 > > org.apache.tomcat.dbcp.dbcp.PoolingDataSource$PoolGuardConnectionWrapper.close(PoolingDataSource.java:181) > > org.springframework.orm.hibernate3.LocalDataSourceConnectionProvider.closeConnection(LocalDataSourceConnectionProvider.java:96) > > org.hibernate.jdbc.ConnectionManager.closeConnection(ConnectionManager.java:451) > org.hibernate.jdbc.ConnectionManager.cleanup(ConnectionManager.java:385) > org.hibernate.jdbc.ConnectionManager.close(ConnectionManager.java:324) > org.hibernate.impl.SessionImpl.close(SessionImpl.java:298) > > org.springframework.orm.hibernate3.SessionFactoryUtils.closeSession(SessionFactoryUtils.java:791) > > org.springframework.orm.hibernate3.SessionFactoryUtils.closeSessionOrRegisterDeferredClose(SessionFactoryUtils.java:777) > > org.springframework.orm.hibernate3.HibernateTransactionManager.doCleanupAfterCompletion(HibernateTransactionManager.java:733) > > org.springframework.transaction.support.AbstractPlatformTransactionManager.cleanupAfterCompletion(AbstractPlatformTransactionManager.java:989) > > org.springframework.transaction.support.AbstractPlatformTransactionManager.processCommit(AbstractPlatformTransactionManager.java:782) > > org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:701) > > org.springframework.transaction.interceptor.TransactionAspectSupport.commitTransactionAfterReturning(TransactionAspectSupport.java:321) > > org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:116) > > org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171) > > org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204) > $Proxy8.execute(Unknown Source) > sun.reflect.GeneratedMethodAccessor67.invoke(Unknown Source) > sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) > java.lang.reflect.Method.invoke(Unknown Source) > org.springframework.util.MethodInvoker.invoke(MethodInvoker.java:276) > > org.springframework.scheduling.quartz.MethodInvokingJobDetailFactoryBean$MethodInvokingJob.executeInternal(MethodInvokingJobDetailFactoryBean.java:260) > > org.springframework.scheduling.quartz.QuartzJobBean.execute(QuartzJobBean.java:86) > org.quartz.core.JobRunShell.run(JobRunShell.java:203) > > org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:520) > > > > Any help or insight into the problem and/or the correct dbcp settings would > be appreciated to ensure that this doesn't happen again. > > Thanks, > > Eric > > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: dev-unsubscr...@tomcat.apache.org > For additional commands, e-mail: dev-h...@tomcat.apache.org > >
