Java forkJoinPool getParallelism() Method

The getParallelism() method of ForkJoinPool class is used to get the parallelism level of the common Pool. It returns an integer value representing the parallelism level.

Syntax

Parameter

Returns

The targeted parallelism level of the common pool

Throws

Does not throw the Exception.

Example 1

        import java.util.concurrent.ForkJoinPool;
        import java.util.concurrent.RecursiveTask;
        public class JavaForkJoingetParallelismExample1  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) {
	      JavaForkJoingetParallelismExample1  left = new JavaForkJoingetParallelismExample1 ();
             JavaForkJoingetParallelismExample1 right = new JavaForkJoingetParallelismExample1 ();
             JavaForkJoingetParallelismExample1  finder = new JavaForkJoingetParallelismExample1 ();
             ForkJoinPool pool = ForkJoinPool.commonPool();
           pool.submit(left); pool.submit(right); pool.submit(finder);
	    System.out.println("Finder :" + pool.invoke(finder) + "    Active threads :" +pool.getActiveThreadCount() + " Left  " +pool.invoke(left) + " Right "+ pool.invoke(right) );
                       System.out.println(" Targeted Parallelism  :" +pool.getParallelism());
	  }
        }

Test it Now

Output:

Finder :0    Active threads :3 Left  0 Right 0
 Targeted Parallelism  :3

Example 2

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.RecursiveAction;
 class TaskL extends RecursiveAction {
     private long Load = 0;
 
 public TaskL(long Load) {
         this.Load = Load;
    }
    @Override
    protected void compute() {
        //if work is above threshold, break tasks up into smaller tasks
        List<TaskL> subtasks = new ArrayList<TaskL>();
        subtasks.addAll(createSubtasks());
         for(RecursiveAction subtask : subtasks){
                subtask.fork();
            }
    }
    private List<TaskL> createSubtasks() {
        List<TaskL> subtasks =new ArrayList<TaskL>();
     TaskL subtask1 = new TaskL(this.Load / 2);
        subtasks.add(subtask1);
        return subtasks;
    }
}
public class JavaForkJoingetParallelismExample2 {
   public static void main(final String[] arguments) throws InterruptedException
      {      
      ForkJoinPool Pool = ForkJoinPool.commonPool();
      int i= Pool.getPoolSize();
      System.out.println("Common Pool Size before  :" +i);
       TaskL t = new TaskL(1000);
       Pool.invoke(t);
       Pool.execute(t);
      System.out.println("Common Pool Size after  :" +Pool.getPoolSize());
        System.out.println(" Parallelism level of pool :" +Pool.getParallelism());
       System.out.println("Is pool use First-in-First-out Scheduling:" +Pool.getAsyncMode());
   }  
}

Test it Now

Output:

Common Pool Size after  :3
 Parallelism level of pool :3
Is pool use First-in-First-out Scheduling:false

Next TopicJava Forkjoinpool

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