IExecutorService Interface

Definition

[Android.Runtime.Register("java/util/concurrent/ExecutorService", "", "Java.Util.Concurrent.IExecutorServiceInvoker")]
public interface IExecutorService : IDisposable, Java.Interop.IJavaPeerable, Java.Util.Concurrent.IExecutor

[<Android.Runtime.Register("java/util/concurrent/ExecutorService", "", "Java.Util.Concurrent.IExecutorServiceInvoker")>]
type IExecutorService = interface
    interface IExecutor
    interface IJavaObject
    interface IDisposable
    interface IJavaPeerable

Derived

Java.Util.Concurrent.AbstractExecutorService

Java.Util.Concurrent.IScheduledExecutorService

Java.Util.Concurrent.ScheduledThreadPoolExecutor

Attributes

RegisterAttribute

Implements

IJavaObject IJavaPeerable IExecutor IDisposable

Remarks

An Executor that provides methods to manage termination and methods that can produce a Future for tracking progress of one or more asynchronous tasks.

An ExecutorService can be shut down, which will cause it to reject new tasks. Two different methods are provided for shutting down an ExecutorService. The #shutdown method will allow previously submitted tasks to execute before terminating, while the #shutdownNow method prevents waiting tasks from starting and attempts to stop currently executing tasks. Upon termination, an executor has no tasks actively executing, no tasks awaiting execution, and no new tasks can be submitted. An unused ExecutorService should be shut down to allow reclamation of its resources.

Method submit extends base method Executor#execute(Runnable) by creating and returning a Future that can be used to cancel execution and/or wait for completion. Methods invokeAny and invokeAll perform the most commonly useful forms of bulk execution, executing a collection of tasks and then waiting for at least one, or all, to complete. (Class ExecutorCompletionService can be used to write customized variants of these methods.)

The Executors class provides factory methods for the executor services provided in this package.

<h2>Usage Examples</h2>

Here is a sketch of a network service in which threads in a thread pool service incoming requests. It uses the preconfigured Executors#newFixedThreadPool factory method:

{@code
            class NetworkService implements Runnable {
              private final ServerSocket serverSocket;
              private final ExecutorService pool;

              public NetworkService(int port, int poolSize)
                  throws IOException {
                serverSocket = new ServerSocket(port);
                pool = Executors.newFixedThreadPool(poolSize);
              }

              public void run() { // run the service
                try {
                  for (;;) {
                    pool.execute(new Handler(serverSocket.accept()));
                  }
                } catch (IOException ex) {
                  pool.shutdown();
                }
              }
            }

            class Handler implements Runnable {
              private final Socket socket;
              Handler(Socket socket) { this.socket = socket; }
              public void run() {
                // read and service request on socket
              }
            }}

The following method shuts down an ExecutorService in two phases, first by calling shutdown to reject incoming tasks, and then calling shutdownNow, if necessary, to cancel any lingering tasks:

{@code
            void shutdownAndAwaitTermination(ExecutorService pool) {
              pool.shutdown(); // Disable new tasks from being submitted
              try {
                // Wait a while for existing tasks to terminate
                if (!pool.awaitTermination(60, TimeUnit.SECONDS)) {
                  pool.shutdownNow(); // Cancel currently executing tasks
                  // Wait a while for tasks to respond to being cancelled
                  if (!pool.awaitTermination(60, TimeUnit.SECONDS))
                      System.err.println("Pool did not terminate");
                }
              } catch (InterruptedException ex) {
                // (Re-)Cancel if current thread also interrupted
                pool.shutdownNow();
                // Preserve interrupt status
                Thread.currentThread().interrupt();
              }
            }}

Memory consistency effects: Actions in a thread prior to the submission of a Runnable or Callable task to an ExecutorService<i>happen-before</i> any actions taken by that task, which in turn happen-before the result is retrieved via Future.get().

Added in 1.5.

Java documentation for java.util.concurrent.ExecutorService.

Portions of this page are modifications based on work created and shared by the Android Open Source Project and used according to terms described in the Creative Commons 2.5 Attribution License.

Properties

Methods

Extension Methods

Applies to