Java ForkJoinPool isQuiescent() Method

The isQuiscent() method of ForkJoinPool class returns true if all the worker threads are currently idle. An idle worker is the one that cannot obtain a task to execute because none are available to steal from other threads, and there are no pending submissions to the pool.

Syntax

Parameter

No parameter is passed.

Returns

True if all threads are currently idle

Throws

Does not throw the exception.

Example 1

import java.util.concurrent.ForkJoinPool;
import static java.util.concurrent.ForkJoinTask.invokeAll;
import java.util.concurrent.RecursiveTask;
import java.util.concurrent.TimeUnit;
public class JavaForkJoinPoolisQuiescenceExample1  {
   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);
      int[] n = {20 , 23 , 5 ,6 ,7,8,23,12,56,1}; 
      ForkJoinPool Pool = new ForkJoinPool(proc);
      Work7 t=new Work7(n,0,n.length);
       System.out.println("  is Quiescent :" + Pool.isQuiescent() );
      ForkJoinPool.commonPool().awaitQuiescence(2, TimeUnit.SECONDS);
    
      Integer r = Pool.invoke(t);
      System.out.println("Pool.invoke :" +r);
      }  
}
class Work7 extends RecursiveTask<Integer> {
      int st;
      int end;
      int[] arr;
      Work7(int[] arr, int st, int end) {
         this.arr = arr;
         this.st  = st;
         this.end  = end;
      }
      protected Integer compute() {
                  if(st - end <= 10) {
            int sum = 0;
               for(int i = st; i < end; ++i) 
               sum += arr[i];
              return sum;
         } else {	    	
            int mid = st + (end - st) / 2;
            Work7 t1 = new Work7(arr, st, mid);
            Work7 t2 = new Work7(arr, st, mid);
            invokeAll(t1 , t2);
             return (t1.join() + t2.join());
         }
      }
   }

Test it Now

Output:

numbers of core available in your processor:4
  is Quiescent :true
Pool.invoke :161

Example 2

import java.util.concurrent.ForkJoinPool;
import static java.util.concurrent.ForkJoinTask.invokeAll;
import java.util.concurrent.RecursiveTask;
import java.util.concurrent.TimeUnit;
public class JavaForkJoinPoolisQuiescenceExample2 {
   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 = new ForkJoinPool(proc);
      Work8 t=new Work8();
      System.out.println("  is Quiescent :" + Pool.isQuiescent() );
   }  
}
   class Work8 extends RecursiveTask<Integer> {
    @Override
      protected Integer compute() {
            Work8 t1 = new Work8();
            Work8 t2 = new Work8();
            invokeAll(t1 , t2);
            return (t1.join() + t2.join());
         }
      }

Test it Now

Output:

numbers of core available in your processor:4
  is Quiescent :true

Next TopicJava ForkJoinPool

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