我正在使用 Spring启动，SQL server activiti，websocket和angularJS 的Web应用程序中工作。
有时，此应用程序UI会挂起（并非总是如此）。我怀疑这是因为连接池。此应用程序使用Spring Boot中的默认数据源属性。到目前为止，没有连接池库。
问题：
我怀疑线程正在等待数据库连接，所以......
1）增加最大活动连接可以解决这个问题吗？
2）使用连接池库可以解决这个问题吗？
我在下面添加了线程转储....
MessageBrokerSockJS-3 prio=10 tid=0x00007f8c1c3d1800 nid=0xebd in Object.wait() [0x00007f8c609c2000]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0x00000007095cd788> (a org.apache.commons.pool.impl.GenericObjectPool$Latch)
at java.lang.Object.wait(Object.java:503)
at org.apache.commons.pool.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:1118)
- locked <0x00000007095cd788> (a org.apache.commons.pool.impl.GenericObjectPool$Latch)
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:204)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:373)
at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:130)
at org.activiti.spring.SpringTransactionInterceptor.execute(SpringTransactionInterceptor.java:45)
at org.activiti.engine.impl.interceptor.LogInterceptor.execute(LogInterceptor.java:31)
at org.activiti.engine.impl.cfg.CommandExecutorImpl.execute(CommandExecutorImpl.java:40)
at org.activiti.engine.impl.cfg.CommandExecutorImpl.execute(CommandExecutorImpl.java:35)
at org.activiti.engine.impl.AbstractQuery.list(AbstractQuery.java:138)
at com.rbccm.workflow.db.dao.ActivitiHelper.getTasksByTaskLocalVar(ActivitiHelper.java:305)
at com.rbccm.workflow.db.dao.ActivitiHelper$$FastClassBySpringCGLIB$$86c44488.invoke(<generated>)
at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:649)
at com.rbccm.workflow.db.dao.ActivitiHelper$$EnhancerBySpringCGLIB$$71f2d0fd.getTasksByTaskLocalVar(<generated>)
at com.rbccm.workflow.manager.ActivitiManager.getTasksByTaskLocalVar(ActivitiManager.java:861)
at com.rbccm.workflow.manager.ActivitiManager$$FastClassBySpringCGLIB$$f69deb1c.invoke(<generated>)
at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:649)
at com.rbccm.workflow.manager.ActivitiManager$$EnhancerBySpringCGLIB$$31946c7.getTasksByTaskLocalVar(<generated>)
at com.rbccm.workflow.manager.AlfrescoManager.unlockTaskForClosedDocument(AlfrescoManager.java:37)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.springframework.scheduling.support.ScheduledMethodRunnable.run(ScheduledMethodRunnable.java:65)
at org.springframework.scheduling.support.DelegatingErrorHandlingRunnable.run(DelegatingErrorHandlingRunnable.java:54)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:304)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:178)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)
"MessageBrokerSockJS-2" prio=10 tid=0x00007f8c1e484000 nid=0xebc waiting on condition [0x00007f8c60ac4000]
java.lang.Thread.State: WAITING (parking)
at sun.misc.Unsafe.park(Native Method)
- parking to wait for <0x00000007041a9590> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2043)
at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1085)
at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:807)
at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1068)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)
"MessageBrokerSockJS-1" prio=10 tid=0x00007f8c1c9c6000 nid=0xeb6 in Object.wait() [0x00007f8c60bc4000]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
- waiting on <0x00000007095d02d8> (a org.apache.commons.pool.impl.GenericObjectPool$Latch)
at java.lang.Object.wait(Object.java:503)
at org.apache.commons.pool.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:1118)
- locked <0x00000007095d02d8> (a org.apache.commons.pool.impl.GenericObjectPool$Latch)
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.DataSourceUtils.doGetConnection(DataSourceUtils.java:111)
at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:77)
at org.springframework.jdbc.core.JdbcTemplate.execute(JdbcTemplate.java:391)
at org.springframework.jdbc.core.JdbcTemplate.update(JdbcTemplate.java:549)
at com.rbccm.workflow.db.dao.ChaserDao.clearOldChasers(ChaserDao.java:111)
at com.rbccm.workflow.db.dao.ChaserDao$$FastClassBySpringCGLIB$$fa074cd3.invoke(<generated>)
at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:717)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:136)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:653)
at com.rbccm.workflow.db.dao.ChaserDao$$EnhancerBySpringCGLIB$$48b6e5eb.clearOldChasers(<generated>)
at com.rbccm.workflow.sendchaser.SendChaser.checkChasers(SendChaser.java:72)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.springframework.scheduling.support.ScheduledMethodRunnable.run(ScheduledMethodRunnable.java:65)
at org.springframework.scheduling.support.DelegatingErrorHandlingRunnable.run(DelegatingErrorHandlingRunnable.java:54)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:304)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:178)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)
"container-0" prio=10 tid=0x00007f8c1c930000 nid=0xeb5 waiting on condition [0x00007f8c60cc6000]
java.lang.Thread.State: TIMED_WAITING (sleeping)
at java.lang.Thread.sleep(Native Method)
at org.apache.catalina.core.StandardServer.await(StandardServer.java:407)
at org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedServletContainer$1.run(TomcatEmbeddedServletContainer.java:146)
"ContainerBackgroundProcessor[StandardEngine[Tomcat].StandardHost[localhost].StandardContext[]]" daemon prio=10 tid=0x00007f8c149fa000 nid=0xeb4 waiting on condition [0x00007f8c60dc7000]
java.lang.Thread.State: TIMED_WAITING (sleeping)
at java.lang.Thread.sleep(Native Method)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1345)
at java.lang.Thread.run(Thread.java:745)
答案 0 :(得分：0)
感谢@Kedar Parikh，您提供的链接对于读取线程转储并找到此问题的根本原因非常有用。
从这个问题的堆栈跟踪，下面的行表示，该线程正在等待从池中借用（获取）数据库连接。
org.apache.commons.pool.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:1118)
在这种情况下，Tomcat挂起，因为某些线程正在等待数据库连接。
当我回答我自己的（另一个）问题时，我能够监控我的数据库连接池。 通过使用此监视器/日志记录，我在应用程序中发现了连接泄漏。
有关如何监视/记录数据库连接池的更多详细信息，请参阅 How to Debug / Log Tomcat JDBC Connection Pool's connections?