package com.atguigu.juc;
【ForkJoin示例】import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.ForkJoinTask;
import java.util.concurrent.RecursiveTask;
import org.junit.Test;
public class TestForkJoinPool {
public static void main(String[] args) {
long start = System.currentTimeMillis();
ForkJoinPool pool = new ForkJoinPool();
ForkJoinTask task = new ForkJoinSum(0L, 30000000000L);
long sum = pool.invoke(task);
System.out.println(sum);
long end = System.currentTimeMillis();
System.out.println("耗费时间为：" + (end - start));
//291 4656
}@Test
public void test1(){
long start = System.currentTimeMillis();
long sum = 0L;
for (long i = 0;
i <= 30000000000L;
i++) {
sum += i;
}
System.out.println(sum);
long end = System.currentTimeMillis();
System.out.println("耗费时间为：" + (end - start));
//69 3966
}
}
class ForkJoinSum extends RecursiveTask{
/**
*
*/
private static final long serialVersionUID = -1257568709792496086L;
private long start;
private long end;
private static final long THRESHOLD = 10000L;
//临界值public ForkJoinSum(long start, long end){
this.start = start;
this.end = end;
}@Override
protected Long compute() {
long length = end - start;
if(length <= THRESHOLD){
long sum = 0L;
for (long i = start;
i <= end;
i++) {
sum += i;
}return sum;
}else{
long middle = (start + end) / 2;
ForkJoinSum left = new ForkJoinSum(start, middle);
left.fork();
ForkJoinSum right = new ForkJoinSum(middle + 1, end);
right.fork();
return left.join() + right.join();
}
}
}
