java线程:jdk 7中的Fork/Join模式

//尚未研究完成...

 

 

package org.bluebear.temp;

import java.util.Arrays;
import java.util.Random;
import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.ForkJoinTask;
import java.util.concurrent.RecursiveAction;
import java.util.concurrent.TimeUnit;

/**
 * RecursiveAction里面只有一个compute抽象方法。
 * 
 * 
 */
public class SortTask extends RecursiveAction {

	private static final long serialVersionUID = -4706085992307767517L;

	final long[] array;
	final int lo;
	final int hi;

	private int THRESHOLD = 30;

	public SortTask(long[] array) {
		this(array, 0, array.length - 1);
	}

	public SortTask(long[] array, int lo, int hi) {
		this.array = array;
		this.lo = lo;
		this.hi = hi;
	}

	@Override
	protected void compute() {
		if (hi - lo < THRESHOLD) {
			sequentiallySort(array, lo, hi);
		} else {
			int pivot = partition(array, lo, hi);
			this.invokeAll(new SortTask(array, lo, pivot - 1), new SortTask(
					array, pivot + 1, hi));
		}

	}

	private int partition(long[] array, int lo, int hi) {
		long x = array[hi];
		int i = lo - 1;
		for (int j = lo; j < hi; j++) {
			if (array[j] <= x) {
				i++;
				swap(array, i, j);
			}
		}
		swap(array, i + 1, hi);
		return i + 1;
	}

	private void swap(long[] array, int i, int j) {
		if (i != j) {
			long temp = array[i];
			array[i] = array[j];
			array[j] = temp;
		}
	}

	private void sequentiallySort(long[] array, int lo, int hi) {
		Arrays.sort(array, lo, hi + 1);
	}

	public static void main(String[] args) throws Exception {
		long[] array = new long[100];
		
		Random random = new Random();
		
		for(int i=0;i<100;i++){
			array[i] = random.nextInt(1000);
		}
		
		ForkJoinTask sort = new SortTask(array);
		ForkJoinPool pool = new ForkJoinPool();
		pool.submit(sort);
		pool.shutdown();
		pool.awaitTermination(30, TimeUnit.SECONDS);
		
		for(int i=0;i<array.length;i++){
			System.out.print(array[i] + " , ");
		}
		
	}

}

 

 

 

 

参考：

http://www.deftitlenil.com/2011/04/blog-post_05.html

http://www.ibm.com/developerworks/cn/java/j-lo-forkjoin/

http://drdobbs.com/blogs/jvm/231000556