Question

Java:

use fork and join to count from 0.0 to 1 million by increments of 0.0001 and print how long its takes

Answer 1

`Hey,

Note: Brother in case of any queries, just comment in box I would be very happy to assist all your queries

File : Step.java

package javaforkjoin;
import java.util.concurrent.ForkJoinPool;

import org.apache.commons.lang3.time.StopWatch;

public class Step {
   static double max = 1000000;
   static double inc = 0.0001;
   public static void main(String[] args) {
      
       method1();
       method2();
      
   }
   private static void method1() {
          
       double d = 0.0;
       StopWatch sw = new StopWatch();
       sw.start();
       while(d < max)
       {
           d += inc;
       }
       sw.stop();
      
       System.out.println("Method 1:"+sw.getTime());
   }
  
   private static void method2() {
       ForkJoinPool pool = new ForkJoinPool();
      
       CounterProcessor forktask = new CounterProcessor(max);

       StopWatch sw = new StopWatch();
       sw.start();
       Double taskResult = pool.invoke(forktask);
sw.stop();
      
       System.out.println("Method 2:"+sw.getTime());
       System.out.println("taskResult = " + taskResult);
      
   }

}

File : Counterprocessor.java

package javaforkjoin;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.RecursiveTask;

import org.apache.commons.lang3.time.StopWatch;

public class CounterProcessor extends RecursiveTask<Double> {

   private Double count = 0.0d;
   static double max = 10000;
   static double inc = 0.0001;
   public CounterProcessor(Double result) {
this.count = result;
}
  
   @Override
   protected Double compute() {
       // TODO Auto-generated method stub
       Double d = 0.0d;
      
       if(this.count > 10001.0d)
       {
           List<CounterProcessor> subtasks =
       new ArrayList<CounterProcessor>();
             
       subtasks.addAll(createSubtasks());

       for(CounterProcessor subtask : subtasks){
       subtask.fork();
       }

       Double result = 0.0d;
       for(CounterProcessor subtask : subtasks) {
       result += subtask.join();
       }
       return result;
       }
       else
       {
           double d1 = 0.0;
          
           while(d1 < max)
           {
               d1 += inc;
           }
           return d1;
       }
      
   }
  
   private List<CounterProcessor> createSubtasks() {
List<CounterProcessor> subtasks =
new ArrayList<CounterProcessor>();
  
  
for(int i = 0; i<10;i++){
subtasks.add(new CounterProcessor(this.count / 10   ));
}
return subtasks;
}

}

Library Used: org.apache.commons.lang3.time.StopWatch

Result on 4 core processor

Method 1:19232
Method 2:7162
taskResult = 1000000.0099198519

Kindly revert for any queries

Thanks.