ExecutorService Interface

A java.util.concurrent.ExecutorService interface is a subinterface of Executor interface, and adds features to manage the lifecycle, both of the individual tasks and of the executor itself.
boolean awaitTermination(long timeout, TimeUnit unit)
Blocks until all tasks have completed execution after a shutdown request, or the timeout occurs, or the current thread is interrupted, whichever happens first.
<T> List<Future<T>>	invokeAll(Collection<? extends Callable<T>> tasks)
Executes the given tasks, returning a list of Futures holding their status and results when all complete.
<T> List<Future<T>>	invokeAll(Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
Executes the given tasks, returning a list of Futures holding their status and results when all complete or the timeout expires, whichever happens first.
<T> T invokeAny(Collection<? extends Callable<T>> tasks)
Executes the given tasks, returning the result of one that has completed successfully (i.e., without throwing an exception), if any do.
<T> T invokeAny(Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
boolean isShutdown()
Returns true if this executor has been shut down.
boolean isTerminated()
Returns true if all tasks have completed following shut down.
void shutdown()
Initiates an orderly shutdown in which previously submitted tasks are executed, but no new tasks will be accepted.
List<Runnable> shutdownNow()
Attempts to stop all actively executing tasks, halts the processing of waiting tasks, and returns a list of the tasks that were awaiting execution.
<T> Future<T>	submit(Callable<T> task)
Submits a value-returning task for execution and returns a Future representing the pending results of the task.
Future<?> submit(Runnable task)
Submits a Runnable task for execution and returns a Future representing that task.
<T> Future<T>	submit(Runnable task, T result)
Submits a Runnable task for execution and returns a Future representing that task.
The following TestThread program shows usage of ExecutorService interface in thread based environment.
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

public class TestThread {

   public static void main(final String[] arguments) throws InterruptedException {
      ExecutorService executor = Executors.newSingleThreadExecutor();

      try {
         executor.submit(new Task());
         System.out.println("Shutdown executor");
         executor.shutdown();
         executor.awaitTermination(5, TimeUnit.SECONDS);
      } catch (InterruptedException e) {
         System.err.println("tasks interrupted");
      } finally {

         if (!executor.isTerminated()) {
            System.err.println("cancel non-finished tasks");
         }
         executor.shutdownNow();
         System.out.println("shutdown finished");
      }
   }

   static class Task implements Runnable {
      
      public void run() {
         
         try {
            Long duration = (long) (Math.random() * 20);
            System.out.println("Running Task!");
            TimeUnit.SECONDS.sleep(duration);
         } catch (InterruptedException e) {
            e.printStackTrace();
         }
      }
   }	   
}
This will produce the following result.
Shutdown executor
Running Task!
shutdown finished
cancel non-finished tasks
java.lang.InterruptedException: sleep interrupted
	at java.lang.Thread.sleep(Native Method)
	at java.lang.Thread.sleep(Thread.java:302)
	at java.util.concurrent.TimeUnit.sleep(TimeUnit.java:328)
	at TestThread$Task.run(TestThread.java:39)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:439)
	at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
	at java.util.concurrent.FutureTask.run(FutureTask.java:138)
	at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
	at java.lang.Thread.run(Thread.java:662)


    16 Lectures 
     2 hours 

 Malhar Lathkar

    19 Lectures 
     5 hours 

 Malhar Lathkar

    25 Lectures 
     2.5 hours 

 Anadi Sharma

    126 Lectures 
     7 hours 

  Tushar Kale

    119 Lectures 
     17.5 hours 

 Monica Mittal

    76 Lectures 
     7 hours 

 Arnab Chakraborty
 Print
 Add Notes
 Bookmark this page