我正在使用spring boot framework构建一个webapp。对于一个特定的进程，我使用两个线程来运行两个不同的存储过程，这需要一些时间。
MyService.java
Thread backgroundProcess;
Thread backgroundProcess2;
@Override
public String retrieveData() {
if(reentrantLock.isLocked() || reentrantLock2.isLocked()){
logger.info("Lock is active");
return Arrays.asList("Process running");
}
backgroundProcess = new Thread(objectOfRunnable1);
backgroundProcess2 = new Thread(objectOfRunnable2);
backgroundProcess.start();
backgroundProcess2.start();
return "Process started";
}
@Override
public Boolean checkStatus() {
if(backgroundProcess.isAlive() || backgroundProcess2.isAlive())
return false;
else
return true;
}
重复调用checkStatus函数，直到它返回true。
RunnableClass1.java
@Override
public void run() {
if(reentrantLock.tryLock()) {
try{
//Run stored procedures
}catch (Exception e) {
logger.error("Exception caught in secondary thread: ", e);
}finally {
reentrantLock.unlock();
}
}
}
RunnableClass2.java
@Override
public void run() {
if(reentrantLock2.tryLock()) {
try{
//Run stored procedures
}catch (Exception e) {
logger.error("Exception caught in secondary thread: ", e);
}finally {
reentrantLock2.unlock();
}
}
}
该过程有效，但在记录期间，我注意到每次运行后线程数都在不断增加。
2018-05-02 20:14:04.537 INFO 5079 --- [ Thread-104] com.thread.utils.FooClass : Logging statement
2018-05-02 20:14:04.537 INFO 5079 --- [ Thread-103] com.thread.utils.FooClass : Logging statement
导致此错误：
org.springframework.orm.jpa.JpaSystemException: Unable to acquire JDBC Connection; nested exception is org.hibernate.exception.GenericJDBCException: Unable to acquire JDBC Connection
at org.springframework.orm.jpa.vendor.HibernateJpaDialect.convertHibernateAccessException(HibernateJpaDialect.java:333)
at org.springframework.orm.jpa.vendor.HibernateJpaDialect.translateExceptionIfPossible(HibernateJpaDialect.java:244)
at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.translateExceptionIfPossible(AbstractEntityManagerFactoryBean.java:488)
at org.springframework.dao.support.ChainedPersistenceExceptionTranslator.translateExceptionIfPossible(ChainedPersistenceExceptionTranslator.java:59)
at org.springframework.dao.support.DataAccessUtils.translateIfNecessary(DataAccessUtils.java:213)
at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:147)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:133)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.data.repository.core.support.SurroundingTransactionDetectorMethodInterceptor.invoke(SurroundingTransactionDetectorMethodInterceptor.java:57)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:213)
at com.sun.proxy.$Proxy136.migrateFlagfilesMonthly(Unknown Source)
at java.lang.Thread.run(Thread.java:748)
Caused by: org.hibernate.exception.GenericJDBCException: Unable to acquire JDBC Connection
at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:47)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:111)
at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:97)
at org.hibernate.resource.jdbc.internal.LogicalConnectionManagedImpl.acquireConnectionIfNeeded(LogicalConnectionManagedImpl.java:87)
at org.hibernate.resource.jdbc.internal.LogicalConnectionManagedImpl.getPhysicalConnection(LogicalConnectionManagedImpl.java:109)
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl.connection(StatementPreparerImpl.java:47)
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$1.doPrepare(StatementPreparerImpl.java:86)
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl$StatementPreparationTemplate.prepareStatement(StatementPreparerImpl.java:172)
at org.hibernate.engine.jdbc.internal.StatementPreparerImpl.prepareStatement(StatementPreparerImpl.java:78)
at org.hibernate.procedure.internal.ProcedureCallImpl.buildOutputs(ProcedureCallImpl.java:404)
at org.hibernate.procedure.internal.ProcedureCallImpl.getOutputs(ProcedureCallImpl.java:372)
at org.hibernate.jpa.internal.StoredProcedureQueryImpl.outputs(StoredProcedureQueryImpl.java:234)
at org.hibernate.jpa.internal.StoredProcedureQueryImpl.execute(StoredProcedureQueryImpl.java:217)
at sun.reflect.GeneratedMethodAccessor336.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.orm.jpa.SharedEntityManagerCreator$DeferredQueryInvocationHandler.invoke(SharedEntityManagerCreator.java:372)
at com.sun.proxy.$Proxy195.execute(Unknown Source)
at org.springframework.data.jpa.repository.query.JpaQueryExecution$ProcedureExecution.doExecute(JpaQueryExecution.java:314)
at org.springframework.data.jpa.repository.query.JpaQueryExecution.execute(JpaQueryExecution.java:85)
at org.springframework.data.jpa.repository.query.AbstractJpaQuery.doExecute(AbstractJpaQuery.java:116)
at org.springframework.data.jpa.repository.query.AbstractJpaQuery.execute(AbstractJpaQuery.java:106)
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.doInvoke(RepositoryFactorySupport.java:483)
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.invoke(RepositoryFactorySupport.java:461)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:56)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:99)
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:282)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:136)
... 12 common frames omitted
Caused by: org.apache.tomcat.jdbc.pool.PoolExhaustedException: [Thread-103] Timeout: Pool empty. Unable to fetch a connection in 30 seconds, none available[size:100; busy:100; idle:0; lastwait:30000].
at org.apache.tomcat.jdbc.pool.ConnectionPool.borrowConnection(ConnectionPool.java:706)
at org.apache.tomcat.jdbc.pool.ConnectionPool.getConnection(ConnectionPool.java:198)
at org.apache.tomcat.jdbc.pool.DataSourceProxy.getConnection(DataSourceProxy.java:132)
at org.hibernate.engine.jdbc.connections.internal.DatasourceConnectionProviderImpl.getConnection(DatasourceConnectionProviderImpl.java:122)
at org.hibernate.internal.AbstractSessionImpl$NonContextualJdbcConnectionAccess.obtainConnection(AbstractSessionImpl.java:386)
at org.hibernate.resource.jdbc.internal.LogicalConnectionManagedImpl.acquireConnectionIfNeeded(LogicalConnectionManagedImpl.java:84)
... 40 common frames omitted
不确定线程数增加的原因。我后来甚至补充说：
logger.info("thread pool: " + (backgroundProcess.getThreadGroup() != null ? backgroundProcess.getThreadGroup().activeCount() : -1));
检查状态，但返回-1表示线程未激活。