Configuring managed executors
You can configure ManagedExecutorService instances to run asynchronous tasks with the specified thread context. It is a best practice for Java™ EE applications to avoid directly managing their own threads; therefore, the ManagedExecutorService extends the JSE ExecutorService to provide a way to start asynchronous tasks within an application server environment. You might also configure the ManagedExecutorService to propagate various thread contexts that are relevant to Java EE applications to the thread of the asynchronous task.
About this task
<featureManager>
<feature>concurrent-1.0</feature>
</featureManager>
Propagation of context to the thread of a task that is run by the ManagedExecutorService is managed by the context service. A default instance of the context service (DefaultContextService) is created by the server and configured to propagate at least classloaderContext, jeeMetadataContext and securityContext. This default context service instance is used if a ManagedExecutorService is created without referring to a specific context service instance or configuring a context service instance directly within. For more information about context service instances, refer to the Configuring thread context service instances topic.
A default managed executor instance (DefaultManagedExecutorService) is available as java:comp/DefaultManagedExecutorService and uses the default context service instance for thread context capture and propagation.
Concurrency policies configure concurrency-related behaviors
and constraints that apply to managed executors, such as maximum concurrency and maximum queue size.
By default, managed executors use a concurrencyPolicy configuration element default
instance, defaultConcurrencyPolicy, which has constraints that are unbounded. This
default concurrency policy is used if you configure a managed executor without referring to or
directly configuring a specific concurrencyPolicy element as a nested element. If
multiple managed executors or other configuration elements refer to the same
concurrencyPolicy element, the constraints in that policy apply across all of those
managed executor instances and other configured resources. You can also configure a managed executor
with a concurrency policy for long-running tasks, which applies to tasks with the
LONGRUNNING_HINT execution property set to true. The configuration
that is specified in the concurrencyPolicy element and the long-running
concurrencyPolicy element applies to tasks submitted to run as soon as possible.
The configuration does not apply to scheduled tasks.
Procedure
Example configuration in the server.xml file:
Example
Managed executor service instances can be injected into application components (by using @Resource) or looked up with resource environment references (resource-env-ref). Regardless of how the instance is obtained, you can use it interchangeably as javax.enterprise.concurrent.ManagedExecutorService or its java.util.concurrent.ExecutorSerivce superclass.
- Example that looks up the default managed
executor:
ManagedExecutorService executor = (ManagedExecutorService) new InitialContext().lookup( "java:comp/DefaultManagedExecutorService"); executor.submit(doSomethingInParallel);
- Example that uses @Resource to inject as
java.util.concurrent.ExecutorService:
@Resource(lookup="concurrent/execSvc1") ExecutorService execSvc1; ... // submit task to run Future<Integer> future1 = execSvc1.submit(new Callable<Integer>() { public Integer call() throws Exception { // java:comp lookup is possible because <jeeMetadataContext> is configured DataSource ds = (DataSource) new InitialContext().lookup("java:comp/env/jdbc/ds1"); ... make updates to the database return updateCount; } }); Future<Integer> future2 = execSvc1.submit(anotherTaskThatUpdatesADatabase); numUpdatesCompleted = future1.get() + future2.get();
- Example that uses @Resource to inject as javax.enterprise.concurrent.ManagedExecutorService:
@Resource(lookup="concurrent/execSvc1") ManagedExecutorService execSvc1; ... // submit task to run Future<Integer> future1 = execSvc1.submit(new Callable<Integer>() { public Integer call() throws Exception { // java:comp lookup is possible because <jeeMetadataContext> is configured DataSource ds = (DataSource) new InitialContext().lookup("java:comp/env/jdbc/ds1"); ... make updates to the database return updateCount; } }); Future<Integer> future2 = execSvc1.submit(anotherTaskThatUpdatesADatabase); numUpdatesCompleted = future1.get() + future2.get();
- Example <resource-env-ref> for java.util.concurrent.ExecutorService in
the web.xml file:
<resource-env-ref> <resource-env-ref-name>concurrent/execSvc2</resource-env-ref-name> <resource-env-ref-type>java.util.concurrent.ExecutorService</resource-env-ref-type> </resource-env-ref>
- Example lookup that uses a resource environment reference:
ExecutorService execSvc2 = (ExecutorService) new InitialContext().lookup("java:comp/env/concurrent/execSvc2"); futures = execSvc2.invokeAll(Arrays.asList(task1, task2, task3));
- Example <resource-env-ref> for javax.enterprise.concurrent.ManagedExecutorService in
the web.xml file:
<resource-env-ref> <resource-env-ref-name>concurrent/execSvc2</resource-env-ref-name> <resource-env-ref-type>javax.enterprise.concurrent.ManagedExecutorService</resource-env-ref-type> </resource-env-ref>
- Example lookup that uses a resource
environment reference and casts to ManagedExecutorService:
ManagedExecutorService execSvc2 = (ManagedExecutorService) new InitialContext().lookup("java:comp/env/concurrent/execSvc2"); futures = execSvc2.invokeAll(Arrays.asList(task1, task2, task3));