Thread management and the Spring Framework

Use the information in the following sections to avoid potential problems with unmanaged threads.

 

Unmanaged threads

Do not use a scenario that can create unmanaged threads, for the following reasons:

• The appserver does not recognize unmanaged threads.

• Unmanaged threads do not have access to Java EE contextual information.

• Unmanaged threads can use resources without being monitored by the application server.

• Unmanaged threads can adversely affect appserver functions such as shutting down gracefully or recovering resources from failure.

• An administrator cannot control the number of unmanaged threads or their use of resources.

The following scenarios are examples of Spring Framework scenarios to avoid:

• registerShutdownHook

  Avoid using the Spring Framework AbstractApplicationContext class and its subclasses. These classes include the public method registerShutdownHook, which creates a thread and registers it with the JVM to run at shutdown to close the application context. As an alternative, an application can use the lifecycle notices that it receives from the appserver container to call close explicitly on the application context.

• WeakReferenceMonitor

  The Spring Framework provides convenience classes for simplified development of EJB components. However, these convenience classes spawn off an unmanaged thread that WeakReferenceMonitor object uses for cleanup.

 

Thread pooling

WAS supports the use of the Spring Framework WorkManagerTaskExecutor class to run work asynchronously.

The WorkManagerTaskExecutor class uses thread pools that are managed by the appserver, and delegates to a configured WorkManager instance. For information about configuring a work manager, see the related topics.

Do not use other TaskExecutor classes that are provided with the Spring Framework, because they might start unmanaged threads. You can use the JNDI name of the configured work manager as a workManagerName property to define a WorkManagerTaskExecutor instance in the Spring configuration file.

The following example uses the JNDI name of the DefaultWorkManager in the appserver, that is, wm/default:

<bean id="myTaskExecutor" 
  class="org.springframework.scheduling.commonj.WorkManagerTaskExecutor">
  <property name="workManagerName" value="wm/default" />
</bean>

 

Scheduling

Use the CommonJ WorkManager scheduling package in the Spring Framework to work with threads that are managed by the appserver. Avoid using other packages, such as the Quartz scheduler, or the Timer in the Java SE Development Kit (JDK), because they can start unmanaged threads.

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Related concepts

Spring Framework

 

Related tasks

Set work managers

 

Related information

Spring Documentation