java threadpoolexecutor怎样监控线程池状态

要监控Java ThreadPoolExecutor的状态，您可以使用以下方法：

1. 继承ThreadPoolExecutor类并重写其beforeExecute()和afterExecute()方法。在这些方法中，您可以记录线程池的状态信息，例如活动线程数、任务队列大小等。

import java.util.concurrent.*;

public class CustomThreadPoolExecutor extends ThreadPoolExecutor {

    public CustomThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue workQueue) {
        super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue);
    }

    @Override
    protected void beforeExecute(Thread t, Runnable r) {
        System.out.println("线程 " + t.getName() + " 开始执行任务 " + r.toString());
        super.beforeExecute(t, r);
    }

    @Override
    protected void afterExecute(Runnable r, Throwable t) {
        System.out.println("线程 " + Thread.currentThread().getName() + " 结束执行任务 " + r.toString());
        super.afterExecute(r, t);
    }

    public static void main(String[] args) {
        CustomThreadPoolExecutor executor = new CustomThreadPoolExecutor(3, 5, 60, TimeUnit.SECONDS, new LinkedBlockingQueue<>(10));
        for (int i = 0; i < 20; i++) {
            executor.execute(new Task("任务 " + i));
        }
        executor.shutdown();
    }
}

class Task implements Runnable {
    private String name;

    public Task(String name) {
        this.name = name;
    }

    @Override
    public void run() {
        // 执行任务逻辑
    }
}

2. 使用Java Management Extensions (JMX)监控线程池状态。JMX提供了一种标准方法来监控和管理Java应用程序。要使用JMX监控ThreadPoolExecutor，您需要启用JMX代理并在代码中注册MBean。

首先，创建一个实现ThreadPoolExecutor的类，并重写newTaskFor()方法以返回一个实现了RunnableScheduledFuture接口的自定义任务类。然后，创建一个MBean类，用于暴露线程池的状态信息。最后，在主类中注册MBean并启动JMX代理。

import java.util.concurrent.*;
import javax.management.*;
import javax.management.remote.*;

public class ThreadPoolExecutorWithJMX extends ThreadPoolExecutor {

    public ThreadPoolExecutorWithJMX(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue workQueue) {
        super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue);
    }

    @Override
    protected  RunnableScheduledFuture newTaskFor(Callable callable) {
        return new CustomScheduledFutureTask<>(callable);
    }

    public static void main(String[] args) throws Exception {
        ThreadPoolExecutorWithJMX executor = new ThreadPoolExecutorWithJMX(3, 5, 60, TimeUnit.SECONDS, new LinkedBlockingQueue<>(10));
        MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();
        ObjectName name = new ObjectName("com.example:type=ThreadPoolExecutor");
        mbs.registerMBean(executor, name);

        // 提交任务并监控线程池状态
        for (int i = 0; i < 20; i++) {
            executor.execute(new Task("任务 " + i));
        }

        // 关闭线程池
        executor.shutdown();

        // 连接到JMX代理并获取线程池状态信息
        JMXServiceURL url = new JMXServiceURL("service:jmx:rmi:///jndi/rmi://localhost:1099/jmxrmi");
        JMXConnector jmxConnector = JMXConnectorFactory.connect(url);
        JMXServiceConnection connection = jmxConnector.getMBeanConnection();
        AttributeList attributes = connection.getAttributes(name, new String[]{"activeCount", "corePoolSize", "maximumPoolSize", "taskCount", "queueCapacity"});
        for (Object attr : attributes) {
            System.out.println(attr);
        }
    }
}

class CustomScheduledFutureTask extends FutureTask implements RunnableScheduledFuture {
    public CustomScheduledFutureTask(Callable callable) {
        super(callable);
    }

    @Override
    public void run() {
        super.run();
    }
}

class Task implements Runnable {
    private String name;

    public Task(String name) {
        this.name = name;
    }

    @Override
    public void run() {
        // 执行任务逻辑
    }
}

运行上述代码后，您可以使用JConsole或VisualVM等工具连接到JMX代理，然后查看线程池的状态信息，如活动线程数、核心线程数、最大线程数、任务队列容量等。