ThreadPoolExecutor不执行所有任务

Question

我有一个ThreadPoolExecutor- corePoolSize = 5，maxPoolSize = 10 queueSize = 10，keepAlive = 1000秒。我正在执行100 Runnable任务。实际执行的任务数量各不相同，并非全部执行。RejectionHandler也没有任何报告。我相信我对ThreadPoolExecutor的理解是错误的。有谁能够帮助我？如何执行所有任务？

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.Executors;
import java.util.concurrent.RejectedExecutionHandler;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

public class TestThreadPoolExecutor {
    public static void main(String[] args) {
     ThreadFactory threadFactory =  Executors.defaultThreadFactory();
    ArrayBlockingQueue<Runnable> arrayBlockingQueue = new ArrayBlockingQueue<Runnable>(10);

    ThreadPoolExecutor threadPoolExecutor =  new ThreadPoolExecutor(5, 10,1000, TimeUnit.SECONDS, arrayBlockingQueue, threadFactory, new RejectedExecutionHandlerImpl());
    MonitorThread monitor = new MonitorThread(threadPoolExecutor, 3);
    Thread monitorThread = new Thread(monitor);
    monitorThread.start();
    for (int i = 0; i < 100; i++) {
        threadPoolExecutor.execute(new DummyRunnableTask(i));
    }
    //threadPoolExecutor.shutdown();
    //monitor.shutDown();
}
}

class DummyRunnableTask implements Runnable {

  private int i;

    public DummyRunnableTask(int i) {
    super();
    this.i = i;
  }

    @Override
    public void run() {
    /*try {
        Thread.sleep(1);
    } catch (InterruptedException e) {
        e.printStackTrace();
    }*/
    System.out.println("Thread Name:=" + Thread.currentThread().getName()+ " is working for id=" + i);
}

}

class RejectedExecutionHandlerImpl implements RejectedExecutionHandler {

    @Override
public void rejectedExecution(Runnable r, ThreadPoolExecutor executor) {
    System.out.println();
}

}

class MonitorThread implements Runnable{
    private ThreadPoolExecutor executor;
    private int seconds;
    private Boolean run = true;
    public MonitorThread(ThreadPoolExecutor executor, int seconds) {
    super();
    this.executor = executor;
    this.seconds = seconds;
  }

    public void shutDown() {
    this.run = false;
  }

    @Override
    public void run() {
    while (run) {
        System.out.println(
                String.format("[monitor] [%d/%d] Active: %d, Completed: %d, Task: %d, isShutdown: %s, isTerminated: %s",
                    this.executor.getPoolSize(),
                    this.executor.getCorePoolSize(),
                    this.executor.getActiveCount(),
                    this.executor.getCompletedTaskCount(),
                    this.executor.getTaskCount(),
                    this.executor.isShutdown(),
                    this.executor.isTerminated()));
            try {
                Thread.sleep(seconds*1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
    }

  }

 }

样本输出：

...............
Thread Name:=pool-1-thread-7 is working for id=97
Thread Name:=pool-1-thread-2 is working for id=95
Thread Name:=pool-1-thread-10 is working for id=94
Thread Name:=pool-1-thread-4 is working for id=93
[monitor] [0/5] Active: 0, Completed: 0, Task: 1, isShutdown: false, isTerminated: false
[monitor] [10/5] Active: 0, Completed: 88, Task: 88, isShutdown: false, isTerminated: false
[monitor] [10/5] Active: 0, Completed: 88, Task: 88, isShutdown: false, isTerminated: false

Answer 1

假设无法处理 100 个线程，因为 maxPoolSize=10 且queueSize = 10，这意味着在最坏的情况下您只能在拉取执行器中放入 20 个线程。最佳情况可能会根据每个线程内作业的性能和复杂性而改变。尝试将队列大小增加到 90。因此，可以肯定，其中 90 个会等待，而其他 10 个将继续工作。您可以在这里找到最好的解释链接：

如果请求无法排队，则会创建一个新线程，除非这超出了 MaximumPoolSize，在这种情况下，该任务将被拒绝。