Module jakarta.concurrency

Package jakarta.enterprise.concurrent

Annotation Type ManagedScheduledExecutorDefinition

@Repeatable(List.class)
@Retention(RUNTIME)
@Target(TYPE)
public @interface ManagedScheduledExecutorDefinition

Defines a ManagedScheduledExecutorService to be injected into ManagedScheduledExecutorService injection points including any required Qualifier annotations specified by qualifiers() and registered in JNDI by the container under the JNDI name that is specified in the name() attribute.

Application components can refer to this JNDI name in the lookup attribute of a Resource annotation,

 @ManagedScheduledExecutorDefinition(
     name = "java:comp/concurrent/MyScheduledExecutor",
     qualifiers = MyQualifier.class,
     context = "java:comp/concurrent/MyScheduledExecutorContext",
     hungTaskThreshold = 30000,
     maxAsync = 3)
 @ContextServiceDefinition(
     name = "java:comp/concurrent/MyScheduledExecutorContext",
     propagated = APPLICATION)
 public class MyServlet extends HttpServlet {
     @Inject
     @MyQualifier
     ManagedScheduledExecutorService myScheduledExecutor1;

     @Resource(lookup = "java:comp/concurrent/MyScheduledExecutor",
               name = "java:comp/concurrent/env/MyScheduledExecutorRef")
     ManagedScheduledExecutorService myScheduledExecutor2;
     ...

 @Qualifier
 @Retention(RetentionPolicy.RUNTIME)
 @Target({ ElementType.FIELD, ElementType.METHOD, ElementType.PARAMETER, ElementType.TYPE })
 public @interface MyQualifier {}
 

Resource environment references in a deployment descriptor can similarly specify the lookup-name,

 <resource-env-ref>
    <resource-env-ref-name>java:comp/env/concurrent/MyScheduledExecutorRef</resource-env-ref-name>
    <resource-env-ref-type>jakarta.enterprise.concurrent.ManagedScheduledExecutorService</resource-env-ref-type>
    <lookup-name>java:comp/concurrent/MyScheduledExecutor</lookup-name>
 </resource-env-ref>
 

You can also define a ManagedScheduledExecutorService with the <managed-scheduled-executor> deployment descriptor element. For example,

 <managed-scheduled-executor>
    <name>java:module/concurrent/MyExecutor</name>
    <context-service-ref>java:module/concurrent/MyExecutorContext</context-service-ref>
    <hung-task-threshold>120000</hung-task-threshold>
    <max-async>5</max-async>
 </managed-scheduled-executor>
 

If a managed-scheduled-executor and ManagedScheduledExecutorDefinition have the same name, their attributes are merged to define a single ManagedScheduledExecutorService definition, with each attribute that is specified in the managed-scheduled-executor deployment descriptor entry taking precedence over the corresponding attribute of the annotation. If any qualifier elements are specified, the set of qualifier elements replaces the qualifiers attribute of the annotation.

Since:

3.0

Required Element Summary

Required Elements

Modifier and Type	Required Element	Description
java.lang.String	name	JNDI name of the ManagedScheduledExecutorService instance.

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element	Description
java.lang.String	context	The name of a ContextService instance which determines how context is applied to tasks and actions that run on this executor.
long	hungTaskThreshold	The amount of time in milliseconds that a task or action can execute before it is considered hung.
int	maxAsync	Upper bound on contextual tasks and actions that this executor will simultaneously execute asynchronously.
java.lang.Class<?>[]	qualifiers	List of required qualifier annotations.
boolean	virtual	Indicates whether this executor is requested to create virtual threads for tasks that do not run inline.

Element Detail

name

java.lang.String name

JNDI name of the ManagedScheduledExecutorService instance. The JNDI name must be in a valid Jakarta EE namespace, such as,

• java:comp
• java:module
• java:app
• java:global

Returns:

ManagedScheduledExecutorService JNDI name.

qualifiers

java.lang.Class<?>[] qualifiers

List of required qualifier annotations.

A ManagedScheduledExecutorService injection point with these qualifier annotations injects a bean that is produced by this ManagedScheduledExecutorDefinition.

The default value is an empty list, indicating that this ManagedScheduledExecutorDefinition does not automatically produce bean instances for any injection points.

When the qualifiers list is non-empty, the container creates a ManagedScheduledExecutorService instance and registers an ApplicationScoped bean for it with the specified required qualifiers and required type of ManagedScheduledExecutorService. The life cycle of the bean aligns with the life cycle of the application and the bean is not accessible from outside of the application. Applications must not configure a java:global name if also configuring a non-empty list of qualifiers.

Applications can define their own Producers for ManagedScheduledExecutorService injection points as long as the qualifier annotations on the producer do not conflict with the non-empty qualifiers() list of a ManagedScheduledExecutorDefinition.

Returns:

list of qualifiers.

Since:

3.1

Default:

{}

context

java.lang.String context

The name of a ContextService instance which determines how context is applied to tasks and actions that run on this executor.

The name can be the name of a ContextServiceDefinition or the name of a context-service deployment descriptor element or the JNDI name of the Jakarta EE default ContextService instance, java:comp/DefaultContextService.

The name of the ContextService must be no more granular than the name of this ManagedScheduledExecutorDefinition. For example, if this ManagedScheduledExecutorDefinition has a name in java:app, the ContextService can be in java:app or java:global, but not in java:module which would be ambiguous as to which module's ContextService definition should be used.

The default value, java:comp/DefaultContextService, is the JNDI name of the Jakarta EE default ContextService.

Returns:

name of the ContextService for capturing and propagating or clearing context.

Default:

"java:comp/DefaultContextService"

hungTaskThreshold

long hungTaskThreshold

The amount of time in milliseconds that a task or action can execute before it is considered hung.

The default value of -1 indicates unlimited.

Returns:

number of milliseconds after which a task or action is considered hung.

Default:

-1L

maxAsync

int maxAsync

Upper bound on contextual tasks and actions that this executor will simultaneously execute asynchronously. This constraint does not apply to tasks and actions that the executor runs inline, such as when a thread requests CompletableFuture.join() and the action runs inline if it has not yet started. This constraint also does not apply to tasks that are scheduled via the schedule* methods or Asynchronous.runAt().

The default value of -1 indicates unbounded, although still subject to resource constraints of the system.

Returns:

upper limit on asynchronous execution.

Default:

-1

virtual

boolean virtual

Indicates whether this executor is requested to create virtual threads for tasks that do not run inline. Virtual threads are discussed in the Thread JavaDoc under the section that is titled Virtual threads.

When true, the executor can create virtual threads if it is capable of doing so and if the request is not overridden by vendor-specific configuration that restricts the use of virtual threads.

The default is false, indicating that the executor must not create virtual threads.

It should be noted that some tasks, such as completion stage actions, can run inline on an existing thread in response to events such as the completion of another stage or a join operation on the completion stage. In situations such as these, the executor does not control the type of thread that is used to run the task.

When running on Java SE 17, the true value behaves the same as the false value and results in platform threads being created rather than virtual threads.

Returns:

true if the executor can create virtual threads, otherwise false.

Since:

3.1

Default:

false