Do not start unmanaged threads within the web or EJB container

This rule flags calls to the start() method on java.lang.Thread objects and calls to the run() method on objects that implement the java.lang.Runnable interface within web and EJB modules.

Managing threads is important within the web or EJB containers. Applications should use the services provided for handling threads instead of starting unmanaged threads for the following reasons:

• The application server does not recognize unmanaged threads.
• Applications running in unmanaged threads do not have access to Java EE contextual information.
• Applications running in unmanaged threads can use resources without being monitored by the application server.
• Unmanaged threads can adversely affect application server functions such as shut down and resource recovery after a failure.
• An administrator cannot control the number of unmanaged threads or their use of resources.

Where possible, configure applications to use the Concurrency Utilities ManagedExecutorService introduced in Java EE 7. For additional information on the Concurrency Utilities APIs, see the following resources:

• Concurrency Utilities for Java EE 1.0
• Configuring ManagedExecutorService instances for configuration information.
• javax.enterprise.concurrent.ManagedExecutorService for API information.

For WebSphere Application Server traditional Version 8.5.5 and prior, use the work manager to schedule asynchronous beans. See Work managers for more information.