如何监控Java ExecutorService线程池状态

要监控Java ExecutorService线程池的状态，您可以使用以下方法：

1. 使用ThreadPoolExecutor类：

如果您使用的是ThreadPoolExecutor，那么可以直接访问其提供的方法来获取线程池的状态。例如：

import java.util.concurrent.Executors;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

public class ThreadPoolMonitor {
    public static void main(String[] args) {
        ThreadPoolExecutor executor = (ThreadPoolExecutor) Executors.newFixedThreadPool(5);

        // 提交任务
        for (int i = 0; i < 10; i++) {
            executor.submit(() -> {
                try {
                    TimeUnit.SECONDS.sleep(1);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            });
        }

        // 监控线程池状态
        monitorThreadPool(executor);
    }

    public static void monitorThreadPool(ThreadPoolExecutor executor) {
        while (true) {
            System.out.println("Pool Size: " + executor.getPoolSize());
            System.out.println("Active Threads: " + executor.getActiveCount());
            System.out.println("Completed Tasks: " + executor.getCompletedTaskCount());
            System.out.println("Task Queue Size: " + executor.getQueue().size());

            try {
                TimeUnit.SECONDS.sleep(5);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}

2. 使用ScheduledExecutorService定期检查：

如果您使用的是Executors.newScheduledThreadPool()创建的线程池，可以使用ScheduledExecutorService定期检查线程池的状态。例如：

import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.ThreadPoolExecutor;

public class ThreadPoolMonitor {
    public static void main(String[] args) {
        ThreadPoolExecutor executor = (ThreadPoolExecutor) Executors.newScheduledThreadPool(5);
        ScheduledExecutorService monitorExecutor = Executors.newScheduledThreadPool(1);

        // 提交任务
        for (int i = 0; i < 10; i++) {
            executor.submit(() -> {
                try {
                    TimeUnit.SECONDS.sleep(1);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            });
        }

        // 定期检查线程池状态
        monitorExecutor.scheduleAtFixedRate(() -> {
            System.out.println("Pool Size: " + executor.getPoolSize());
            System.out.println("Active Threads: " + executor.getActiveCount());
            System.out.println("Completed Tasks: " + executor.getCompletedTaskCount());
            System.out.println("Task Queue Size: " + executor.getQueue().size());
        }, 0, 5, TimeUnit.SECONDS);
    }
}

注意：在实际应用中，您可能需要根据实际需求调整监控频率和监控指标。同时，不要忘记在适当的时候关闭线程池和监控线程池。