并发编程：并发测试：监测Fork/Join任务池

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本文介绍了一个使用 Java 的 Fork/Join 框架实现的示例程序，展示了如何通过递归任务来分解和合并计算结果，并监控线程池的状态。包括主程序的设计、任务类的实现及执行过程中的状态变化。

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fork/join任务池

getPoolSize():当前线程池内工作线程的数量
getParallelism():并行级别
getActiveThreadCount():正在执行任务的线程数
getRunningThreadCount():正在运行的（没有被阻塞的）工作线程数
getQueuedSubmissionCount():提交到线程池中，但尚未开始执行的任务数量
getQueuedTaskCount():提交到线程池中，已经开始执行任务的数量
getStealCount():工作线程队列从另外一个工作线程队列中窃取的全部任务数量。

一、主程序

package xyz.jangle.thread.test.n9_5.testforkjoin;

import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.TimeUnit;

/**
 * 9.5、监测fork/join任务池
 * 
 * @author jangle
 * @email jangle@jangle.xyz
 * @time 2020年10月24日 下午4:34:27
 * 
 */
public class M {

	public static void main(String[] args) throws InterruptedException {

		ForkJoinPool pool = new ForkJoinPool();
		int array[] = new int[10000];
		var task = new Task(array, 0, array.length);
		pool.execute(task);
		while (!task.isDone()) {
			showLog(pool);
			TimeUnit.SECONDS.sleep(1);
		}
		pool.shutdown();
		pool.awaitTermination(1, TimeUnit.DAYS);
		showLog(pool);
		System.out.println("M:End ");

	}

	private static void showLog(ForkJoinPool pool) {
		System.out.println("*****************************");
		System.out.println("pool.getParallelism():" + pool.getParallelism());
		System.out.println("pool.getPoolSize():" + pool.getPoolSize());
		System.out.println("pool.getActiveThreadCount():" + pool.getActiveThreadCount());
		System.out.println("pool.getRunningThreadCount():" + pool.getRunningThreadCount());
		System.out.println("pool.getQueuedSubmissionCount():" + pool.getQueuedSubmissionCount());
		System.out.println("pool.getQueuedTaskCount():" + pool.getQueuedTaskCount());
		System.out.println("pool.hasQueuedSubmissions():" + pool.hasQueuedSubmissions());
		System.out.println("pool.getStealCount():" + pool.getStealCount());
		System.out.println("pool.isTerminated():" + pool.isTerminated());
		System.out.println("*****************************");

	}

}

二、任务类

package xyz.jangle.thread.test.n9_5.testforkjoin;

import java.util.concurrent.RecursiveAction;

/**
 * @author jangle
 * @email jangle@jangle.xyz
 * @time 2020年10月24日 下午4:41:58
 * 
 */
@SuppressWarnings("serial")
public class Task extends RecursiveAction {

	private final int array[];

	private final int start, end;

	public Task(int[] array, int start, int end) {
		super();
		this.array = array;
		this.start = start;
		this.end = end;
	}

	@Override
	protected void compute() {
		if (end - start > 100) {
			int mid = (start + end) / 2;
			var task1 = new Task(array, start, mid);
			var task2 = new Task(array, mid, end);
			task1.fork();
			task2.fork();
			task1.join();
			task2.join();
		} else {
			for (int i = start; i < end; i++) {
				array[i]++;
				try {
					Thread.sleep(5);
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
			}
		}

	}

}

三、执行结果

*****************************
pool.getParallelism():8
pool.getPoolSize():1
pool.getActiveThreadCount():1
pool.getRunningThreadCount():1
pool.getQueuedSubmissionCount():0
pool.getQueuedTaskCount():1
pool.hasQueuedSubmissions():false
pool.getStealCount():0
pool.isTerminated():false
*****************************
*****************************
pool.getParallelism():8
pool.getPoolSize():8
pool.getActiveThreadCount():7
pool.getRunningThreadCount():0
pool.getQueuedSubmissionCount():0
pool.getQueuedTaskCount():16
pool.hasQueuedSubmissions():false
pool.getStealCount():0
pool.isTerminated():false
*****************************
*****************************
pool.getParallelism():8
pool.getPoolSize():8
pool.getActiveThreadCount():7
pool.getRunningThreadCount():0
pool.getQueuedSubmissionCount():0
pool.getQueuedTaskCount():22
pool.hasQueuedSubmissions():false
pool.getStealCount():4
pool.isTerminated():false
*****************************
*****************************
pool.getParallelism():8
pool.getPoolSize():8
pool.getActiveThreadCount():7
pool.getRunningThreadCount():0
pool.getQueuedSubmissionCount():0
pool.getQueuedTaskCount():15
pool.hasQueuedSubmissions():false
pool.getStealCount():4
pool.isTerminated():false
*****************************
*****************************
pool.getParallelism():8
pool.getPoolSize():8
pool.getActiveThreadCount():7
pool.getRunningThreadCount():0
pool.getQueuedSubmissionCount():0
pool.getQueuedTaskCount():20
pool.hasQueuedSubmissions():false
pool.getStealCount():4
pool.isTerminated():false
*****************************
*****************************
pool.getParallelism():8
pool.getPoolSize():8
pool.getActiveThreadCount():7
pool.getRunningThreadCount():0
pool.getQueuedSubmissionCount():0
pool.getQueuedTaskCount():6
pool.hasQueuedSubmissions():false
pool.getStealCount():4
pool.isTerminated():false
*****************************
*****************************
pool.getParallelism():8
pool.getPoolSize():8
pool.getActiveThreadCount():7
pool.getRunningThreadCount():0
pool.getQueuedSubmissionCount():0
pool.getQueuedTaskCount():11
pool.hasQueuedSubmissions():false
pool.getStealCount():5
pool.isTerminated():false
*****************************
*****************************
pool.getParallelism():8
pool.getPoolSize():8
pool.getActiveThreadCount():7
pool.getRunningThreadCount():0
pool.getQueuedSubmissionCount():0
pool.getQueuedTaskCount():4
pool.hasQueuedSubmissions():false
pool.getStealCount():5
pool.isTerminated():false
*****************************
*****************************
pool.getParallelism():8
pool.getPoolSize():8
pool.getActiveThreadCount():6
pool.getRunningThreadCount():0
pool.getQueuedSubmissionCount():0
pool.getQueuedTaskCount():2
pool.hasQueuedSubmissions():false
pool.getStealCount():5
pool.isTerminated():false
*****************************
*****************************
pool.getParallelism():8
pool.getPoolSize():0
pool.getActiveThreadCount():0
pool.getRunningThreadCount():0
pool.getQueuedSubmissionCount():0
pool.getQueuedTaskCount():0
pool.hasQueuedSubmissions():false
pool.getStealCount():18
pool.isTerminated():true
*****************************
M:End