USING SIMPLE JAVA CODE TAKE GIVEN CODE AND MODIFY MODIFY GIVEN CODE USING JAVA RECURSIVE ACTION DO THE SAME JOB BUT USING RECURSIVE ACTION INSTEAD OF RECURSIVE TASK SAMPLE CODE BELOW
USING SIMPLE JAVA CODE TAKE GIVEN CODE AND MODIFY
MODIFY GIVEN CODE USING JAVA RECURSIVE ACTION
DO THE SAME JOB BUT USING RECURSIVE ACTION INSTEAD OF RECURSIVE TASK
SAMPLE CODE BELOW
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import java.util.concurrent.ExecutionException;
import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.RecursiveTask; //replace with recursive action to do same job below//
public class SumWithPool{
public static void main(String[] args) throws InterruptedException,
ExecutionException {
//get the number of avaialbe CPUs
int nThreads = Runtime.getRuntime().availableProcessors();
System.out.println("Available CPUs: " + nThreads);
//create an array of data
int n = 10; //initital data size
if(args.length > 0) // use the user given data size
n = Integer.parseInt(args[0]);
int[] numbers = new int[n];
for(int i = 0; i < numbers.length; i++) {
numbers[i] = i;
}
ForkJoinPool forkJoinPool = new ForkJoinPool(nThreads);
Sum s = new Sum(numbers,0,numbers.length);
long startTime = System.currentTimeMillis(); //start timer
Long result = forkJoinPool.invoke(s);
long endTime = System.currentTimeMillis();
long timeElapsed = endTime - startTime;
System.out.println("Concurrent executing time: " + timeElapsed + "ms");
System.out.println("The conccurent sum: " + result);
//redo the task sequentially
startTime = System.currentTimeMillis(); //start timer
result = sum(numbers);
endTime = System.currentTimeMillis();
timeElapsed = endTime - startTime;
System.out.println("\nSequential executing time: " + timeElapsed + "ms");
System.out.println("The sequential sum: " + result);
}
/** sequential sum */
private static long sum(int[] arr){
long sum = 0;
for(int i = 0; i < arr.length; i++)
sum += arr[i];
return sum;
}
}
/** create a class that handle a task */
class Sum extends RecursiveTask<Long> {
private int low;
private int high;
private int[] array; //only reference to the given data
/** map the attribute to the given data */
public Sum(int[] array, int low, int high) {
this.array = array;
this.low = low;
this.high = high;
}
/** overriding tehe comput method */
protected Long compute() {
if(high - low <= 10) { //do the sum if the block of data is managable
long sum = 0;
for(int i = low; i < high; ++i)
sum += array[i];
return sum;
} else {
int mid = low + (high - low) / 2;
Sum left = new Sum(array, low, mid);
Sum right = new Sum(array, mid, high);
left.fork();
long rightResult = right.compute();
long leftResult = left.join();
return leftResult + rightResult;
}
}
}
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