Package jakarta.enterprise.concurrent

Interface ManagedThreadFactory

All Superinterfaces:
ForkJoinPool.ForkJoinWorkerThreadFactory, ThreadFactory
public interface ManagedThreadFactory extends ThreadFactory, ForkJoinPool.ForkJoinWorkerThreadFactory
A manageable version of a ThreadFactory.

A ManagedThreadFactory extends the Java™ SE ThreadFactory to provide a method for creating threads for execution in a Jakarta™ EE environment. Implementations of the ManagedThreadFactory are provided by a Jakarta EE Product Provider. Application Component Providers use the Java Naming and Directory Interface™ (JNDI) to look-up instances of one or more ManagedThreadFactory objects using resource environment references.

The Jakarta Concurrency specification describes several behaviors that a ManagedThreadFactory can implement. The Application Component Provider and Deployer identify these requirements and map the resource environment reference appropriately.

Threads returned from the newThread() method should implement the ManageableThread interface. The Runnable task that is allocated to the new thread using the ThreadFactory.newThread(Runnable) method will run with the application component context of the component instance that created (looked-up) this ManagedThreadFactory instance.

The ForkJoinWorkerThread that is created by the ForkJoinPool.ForkJoinWorkerThreadFactory.newThread(ForkJoinPool) method runs tasks with the application component context of the component instance that created (looked-up) this ManagedThreadFactory instance. The Jakarta EE Product Provider establishes the context once per ForkJoinWorkerThread and does not reset the context between operations that run on the ForkJoinWorkerThread.

The task runs without an explicit transaction (they do not enlist in the application component's transaction). If a transaction is required, use a jakarta.transaction.UserTransaction instance. A UserTransaction instance is available in JNDI using the name: "java:comp/UserTransaction"

Example: 

 public run() {
   // Begin of task
   InitialContext ctx = new InitialContext();
   UserTransaction ut = (UserTransaction) ctx.lookup("java:comp/UserTransaction");
   ut.begin();

   // Perform transactional business logic

   ut.commit();
 }
A ManagedThreadFactory can be used with Java SE ExecutorService implementations directly.

Example: 

 /**
 * Create a ThreadPoolExecutor using a ManagedThreadFactory.
 * Resource Mappings:
 *  type:      jakarta.enterprise.concurrent.ManagedThreadFactory
 *  jndi-name: concurrent/tf/DefaultThreadFactory
 */

 @Resource(name="concurrent/tf/DefaultThreadFactory")
 ManagedThreadFactory tf;

 public ExecutorService getManagedThreadPool() {

   // All threads will run as part of this application component.
   return new ThreadPoolExecutor(5, 10, 5, TimeUnit.SECONDS,
       new ArrayBlockingQueue<Runnable>(10), tf);
 }

ForkJoinPool Example: 

 ManagedThreadFactory threadFactory =
   InitialContext.doLookup("java:comp/DefaultManagedThreadFactory");

 ForkJoinPool pool = new ForkJoinPool(
     Runtime.getRuntime().availableProcessors(), threadFactory, null, false);

 ForkJoinTask<Double> totals = pool.submit(() -> orders
     .parallelStream()
     .map(order -> {
         if (order.total == 0.0) {
             // lookups require application component namespace:
             try (Connection con = ((DataSource)
                     InitialContext.doLookup(
                             "java:comp/env/jdbc/ds1"))
                     .getConnection()) {
                 order.total = ...
             } catch (NamingException | SQLException x) {
                 throw new CompletionException(x);
             }
         }
         return order.total;
      })
     .reduce(0.0, Double::sum));

 System.out.println("Sum is: " + totals.join());
 pool.shutdown();

Since:
1.0