java - 无法打开 JPA EntityManager 进行事务处理；嵌套异常是 java.lang.IllegalStateException

Question

我对 Spring 和 Spring-Batch 非常陌生。 尽管如此，我还是设法安装了 Spring Batch-Admin。我添加了自定义作业和 Hibernate/JPA 以实现持久性。

一切都按预期工作，直到第一个 block 应该被持久化。然后我收到以下错误消息:

org.springframework.transaction.CannotCreateTransactionException: 
      Could not open JPA  EntityManager for transaction;

nested exception is java.lang.IllegalStateException: Already value
      [org.springframework.jdbc.datasource.ConnectionHolder@60d31437] 
      for key [org.springframework.jdbc.datasource.DriverManagerDataSource@12da4b19] 
      bound to thread [jobLauncherTaskExecutor-1]

这是完整的堆栈跟踪:

org.springframework.transaction.CannotCreateTransactionException: Could not open JPA  EntityManager for transaction; nested exception is java.lang.IllegalStateException: Already value [org.springframework.jdbc.datasource.ConnectionHolder@43f9e588] for key [org.springframework.jdbc.datasource.DriverManagerDataSource@84f171a] bound to thread [jobLauncherTaskExecutor-1]
     at org.springframework.orm.jpa.JpaTransactionManager.doBegin(JpaTransactionManager.java:427)
     at org.springframework.transaction.support.AbstractPlatformTransactionManager.getTransaction(AbstractPlatformTransactionManager.java:371)
     at org.springframework.transaction.interceptor.TransactionAspectSupport.createTransactionIfNecessary(TransactionAspectSupport.java:335)
     at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:105)
     at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
     at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202)
     at com.sun.proxy.$Proxy41.saveIfUnique(Unknown Source)
     at com.qompa.batch.ArticleItemWriter.write(ArticleItemWriter.java:28)
     at org.springframework.batch.core.step.item.SimpleChunkProcessor.writeItems(SimpleChunkProcessor.java:171)
     at org.springframework.batch.core.step.item.SimpleChunkProcessor.doWrite(SimpleChunkProcessor.java:150)
     at org.springframework.batch.core.step.item.FaultTolerantChunkProcessor$3.doWithRetry(FaultTolerantChunkProcessor.java:313)
     at org.springframework.batch.retry.support.RetryTemplate.doExecute(RetryTemplate.java:240)
     at org.springframework.batch.retry.support.RetryTemplate.execute(RetryTemplate.java:187)
     at org.springframework.batch.core.step.item.BatchRetryTemplate.execute(BatchRetryTemplate.java:213)
     at org.springframework.batch.core.step.item.FaultTolerantChunkProcessor.write(FaultTolerantChunkProcessor.java:402)
     at org.springframework.batch.core.step.item.SimpleChunkProcessor.process(SimpleChunkProcessor.java:194)
     at org.springframework.batch.core.step.item.ChunkOrientedTasklet.execute(ChunkOrientedTasklet.java:74)
     at org.springframework.batch.core.step.tasklet.TaskletStep$ChunkTransactionCallback.doInTransaction(TaskletStep.java:386)
     at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:130)
     at org.springframework.batch.core.step.tasklet.TaskletStep$2.doInChunkContext(TaskletStep.java:264)
     at org.springframework.batch.core.scope.context.StepContextRepeatCallback.doInIteration(StepContextRepeatCallback.java:76)
     at org.springframework.batch.repeat.support.RepeatTemplate.getNextResult(RepeatTemplate.java:367)
     at org.springframework.batch.repeat.support.RepeatTemplate.executeInternal(RepeatTemplate.java:214)
     at org.springframework.batch.repeat.support.RepeatTemplate.iterate(RepeatTemplate.java:143)
     at org.springframework.batch.core.step.tasklet.TaskletStep.doExecute(TaskletStep.java:250)
     at org.springframework.batch.core.step.AbstractStep.execute(AbstractStep.java:195)
     at org.springframework.batch.core.job.SimpleStepHandler.handleStep(SimpleStepHandler.java:135)
     at org.springframework.batch.core.job.flow.JobFlowExecutor.executeStep(JobFlowExecutor.java:61)
     at org.springframework.batch.core.job.flow.support.state.StepState.handle(StepState.java:60)
     at org.springframework.batch.core.job.flow.support.SimpleFlow.resume(SimpleFlow.java:144)
     at org.springframework.batch.core.job.flow.support.SimpleFlow.start(SimpleFlow.java:124)
     at org.springframework.batch.core.job.flow.FlowJob.doExecute(FlowJob.java:135)
     at org.springframework.batch.core.job.AbstractJob.execute(AbstractJob.java:281)
     at org.springframework.batch.core.launch.support.SimpleJobLauncher$1.run(SimpleJobLauncher.java:120)
     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
     at java.lang.Thread.run(Thread.java:724)
Caused by: java.lang.IllegalStateException: Already value [org.springframework.jdbc.datasource.ConnectionHolder@43f9e588] for key [org.springframework.jdbc.datasource.DriverManagerDataSource@84f171a] bound to thread [jobLauncherTaskExecutor-1]
     at org.springframework.transaction.support.TransactionSynchronizationManager.bindResource(TransactionSynchronizationManager.java:189)
     at org.springframework.orm.jpa.JpaTransactionManager.doBegin(JpaTransactionManager.java:402)
... 36 more

相同的作业在独立应用程序中执行良好。该问题仅出现在 Spring-Batch-Admin 环境中。下面你可以看到项目结构和依赖关系:

这是覆盖/扩展 Batch-Admin 配置的 app-context.xml:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:batch="http://www.springframework.org/schema/batch"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:task="http://www.springframework.org/schema/task" xmlns:jdbc="http://www.springframework.org/schema/jdbc"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xsi:schemaLocation="http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
        http://www.springframework.org/schema/batch http://www.springframework.org/schema/batch/spring-batch-2.1.xsd
        http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-3.0.xsd
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd
        http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task-3.2.xsd">

    <context:component-scan base-package="com.company.batch" />

    <context:property-placeholder location="classpath:batch.properties" />

    <import resource="classpath:/META-INF/spring/batch/jobs/article-job.xml" />

    <bean id="dataSource"
        class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="${batch.jdbc.driver}" />
        <property name="url" value="${batch.jdbc.url}" />
        <property name="username" value="${batch.jdbc.user}" />
        <property name="password" value="${batch.jdbc.password}" />
    </bean>

    <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
        <property name="dataSource" ref="dataSource"></property>
    </bean>

    <bean id="entityManagerFactory"
        class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <property name="packagesToScan" value="com.qompa.batch" />
        <property name="jpaVendorAdapter">
            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
                <property name="database" value="POSTGRESQL"></property>
                <property name="showSql" value="true" />
                <property name="generateDdl" value="false" />
                <property name="databasePlatform" value="com.company.utils.persistence.CustomPGDialect" />
            </bean>
        </property>
        <property name="jpaProperties">
            <props>
                <prop key="hibernate.hbm2ddl.auto"></prop>
            </props>
        </property>
    </bean>

    <bean id="txManager" class="org.springframework.orm.jpa.JpaTransactionManager">
        <property name="entityManagerFactory" ref="entityManagerFactory" />
    </bean>
    <tx:annotation-driven transaction-manager="txManager" />

    <!-- schedule tasks -->
    <task:scheduled-tasks>
        <task:scheduled ref="articleRetrieval" method="run"
            cron="0 0 */4 * * *" />
        <task:scheduled ref="articleConversion" method="run"
            cron="0 15 */4 * * *" />
    </task:scheduled-tasks>
</beans>

到目前为止，我的理解是它与 ThreadPoolTaskExecutor 有关。 jobLauncherTaskExecutor bean 所引用的。它似乎可以处理同时运行的作业的连接池 ...但老实说，我不知道如何更改我的配置以使这些工作正常。

[编辑]:我什至不确定它是否是前面提到的 ThreadPoolTask​​Executor。但它似乎是 TaskExecutor 的实现界面。

如果有人遇到类似的问题，或者有建议如何配置我的应用程序，以便为我的持久性方法创建事务:请给我一个提示!

Answer 1

错误来自 JpaTransactionManager 第 403 行:

TransactionSynchronizationManager.bindResource(getDataSource(), conHolder);

错误意味着事务管理器正在尝试将数据源(不是实体管理器)绑定(bind)到线程，但数据源已经存在，这是意料之外的。

请注意，事务管理器尚未开始将实体管理器绑定(bind)到线程，接下来将在 JpaTransactionManager 行 416 处发生:

有两种可能的解释:

• 有人(另一个事务管理器？)正在将数据源添加到事务管理器之前的线程中，这是意料之外的。

• 或者没有人将数据源添加到事务管理器，只是在任务执行结束时没有人在将线程返回到池之前清理线程，可能是由于错误或未处理的异常。

一个问题，这是否也只发生在一个执行线程上，还是仅在有多个执行线程时发生？

要找出问题所在，请执行以下步骤:

• 使用导致问题的最少线程数运行

• 在TransactionSynchronizationManager.bindResource() 中放一个断点，看看是谁将连接添加到线程。断点可以是 conditional breakpoint线程名称的条件:“jobLauncherTaskExecutor-1”.equals(Thread.currentThread().getName())

• 在 TransactionSynchronizationManager.unbindResource() 中也放一个断点，以查看数据源是否与线程解除绑定(bind)。当断点命中时，向下滚动堆栈跟踪并查看哪些类导致了这种情况。