Java中消息队列任务的平滑关闭详解

Runtime.getRuntime().addShutdownHook(new Thread() {
 public void run() {
 //关闭订阅者
 //关闭线程池
 //退出
 }
});

 //注册linux kill信号量 kill -12
Signal sig = new Signal("USR2");
Signal.handle(sig, new SignalHandler() {
 @Override
 public void handle(Signal signal) {
 //关闭订阅者
 //关闭线程池
 //退出
 }
});

package com.lujianing.demo;

import sun.misc.Signal;
import sun.misc.SignalHandler;
import java.util.concurrent.*;

/**
 * @author lujianing01@58.com
 * @Description:
 * @date 2016/11/14
 */
public class MsgClient {

 //模拟消费线程池 同时4个线程处理
 private static final ThreadPoolExecutor THREAD_POOL = (ThreadPoolExecutor) Executors.newFixedThreadPool(4);
 
 //模拟消息生产任务
 private static final ScheduledExecutorService SCHEDULED_EXECUTOR_SERVICE = Executors.newSingleThreadScheduledExecutor();
 
 //用于判断是否关闭订阅
 private static volatile boolean isClose = false;

 public static void main(String[] args) throws InterruptedException {
 
 //注册钩子方法
 Runtime.getRuntime().addShutdownHook(new Thread() {
  public void run() {
  close();
  }
 });

 BlockingQueue <String> queue = new ArrayBlockingQueue<String>(100);
 producer(queue);
 consumer(queue);

 }

 //模拟消息队列生产者
 private static void producer(final BlockingQueue queue){
 //每200毫秒向队列中放入一个消息
 SCHEDULED_EXECUTOR_SERVICE.scheduleAtFixedRate(new Runnable() {
  public void run() {
  queue.offer("");
  }
 }, 0L, 200L, TimeUnit.MILLISECONDS);
 }

 //模拟消息队列消费者 生产者每秒生产5个 消费者4个线程消费1个1秒 每秒积压1个
 private static void consumer(final BlockingQueue queue) throws InterruptedException {
 while (!isClose){
  getPoolBacklogSize();
  //从队列中拿到消息
  final String msg = (String)queue.take();
  //放入线程池处理
  if(!THREAD_POOL.isShutdown()) {
  THREAD_POOL.execute(new Runnable() {
   public void run() {
   try {
    //System.out.println(msg);
    TimeUnit.MILLISECONDS.sleep(1000L);
   } catch (InterruptedException e) {
    e.printStackTrace();
   }
   }
  });
  }
 }
 }

 //查看线程池堆积消息个数
 private static long getPoolBacklogSize(){
 long backlog = THREAD_POOL.getTaskCount()- THREAD_POOL.getCompletedTaskCount();
 System.out.println(String.format("[%s]THREAD_POOL backlog:%s",System.currentTimeMillis(),backlog));
 return backlog;
 }

 private static void close(){
 System.out.println("收到kill消息，执行关闭操作");
 //关闭订阅消费
 isClose = true;
 //关闭线程池，等待线程池积压消息处理
 THREAD_POOL.shutdown();
 //判断线程池是否关闭
 while (!THREAD_POOL.isTerminated()) {
  try {
  //每200毫秒 判断线程池积压数量
  getPoolBacklogSize();
  TimeUnit.MILLISECONDS.sleep(200L);
  } catch (InterruptedException e) {
  e.printStackTrace();
  }
 }
 System.out.println("订阅者关闭，线程池处理完毕");
 }

 static {
 String osName = System.getProperty("os.name").toLowerCase();
 if(osName != null && osName.indexOf("window") == -1) {
  //注册linux kill信号量 kill -12
  Signal sig = new Signal("USR2");
  Signal.handle(sig, new SignalHandler() {
  @Override
  public void handle(Signal signal) {
   close();
  }
  });
 }
 }

}

java -cp /home/work/lujianing/msg-queue-client/* com.lujianing.demo.MsgClient

ps -fe|grep MsgClient