shutdownNow() Method

The shutdownNow() method of ForkJoinPool class attempts to cancel and/or stop all tasks, and reject all subsequently submitted tasks.

Syntax

Parameter

No parameter is passed.

Returns

An empty list

Throw

Does not throw the exception.

Example 1

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.RecursiveAction;
  class Taaskk1 extends RecursiveAction {
     private long Load = 0;
  public Taaskk1(long Load) {
         this.Load = Load;
    }
    @Override
    protected void compute() {
        //if work is above threshold, break tasks up into smaller tasks
            List<Taaskk1> subtasks = new ArrayList<Taaskk1>();
                     subtasks.addAll(createSubtasks());
            for(RecursiveAction subtask : subtasks){
                subtask.fork();
            } 
    }
   private List<Taaskk1> createSubtasks() {
        List<Taaskk1> subtasks =new ArrayList<Taaskk1>();

     Taaskk1 subtask1 = new Taaskk1(this.Load / 2);
     Taaskk1 subtask2 = new Taaskk1(this.Load / 2);
      Taaskk1 subtask3 = new Taaskk1(this.Load / 2);
        subtasks.add(subtask1);
        subtasks.add(subtask2);
        subtasks.add(subtask3);
        return subtasks;
    }
}
public class JavaForkJoinShutdownNowExample1  {
   public static void main(final String[] arguments) throws InterruptedException
      {      
      int proc = Runtime.getRuntime().availableProcessors();
      System.out.println("numbers of core available in your processor:"  +proc);
      ForkJoinPool Pool = ForkJoinPool.commonPool();
      System.out.println(" Before invoking number of active thread   :" +Pool.getActiveThreadCount());
       Taaskk1 t = new Taaskk1(400);
       Pool.invoke(t); 
      Pool.shutdownNow();
      System.out.println(" After Shutdown  :" +Pool.isShutdown());
      System.out.println("Common Pool Size   :" +Pool.getPoolSize());
   }  
}

Test it Now

Output:

numbers of core available in your processor:4
 Before invoking number of active thread   :0
 After Shutdown  :false
Common Pool Size   :3

Example 2

            import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.RecursiveTask;
        public class JavaForkJoinShutdownNowExample2  extends RecursiveTask<Integer> {
               @Override
              protected Integer compute() {
                  try{
                       throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
                  }
                  catch(Exception e)
                  { 
                  }
                  return 0;
               }
               public static void main(String[] args) {
      JavaForkJoinShutdownNowExample2  left = new JavaForkJoinShutdownNowExample2 ();
             JavaForkJoinShutdownNowExample2  right = new JavaForkJoinShutdownNowExample2 ();
             JavaForkJoinShutdownNowExample2  finder = new JavaForkJoinShutdownNowExample2 ();
             ForkJoinPool pool = ForkJoinPool.commonPool();
           pool.submit(left); pool.submit(right); pool.submit(finder);
            pool.shutdownNow();
	    System.out.println(" || Finder :" + pool.invoke(finder) + " ||  Shutdown " +pool.isShutdown()   + " || Active threads :" +pool.getActiveThreadCount() + " Left  " +pool.invoke(left) + " Right "+ pool.invoke(right) );
               }
}   

Test it Now

Output:

|| Finder :0 ||  Shutdown false || Active threads :0 Left  0 Right 0

Next TopicJava ForkJoinPool

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