预初始化工作线程池以重用连接对象(套接字)

Question

我需要在Java中构建一个工作池,每个工作者都有自己的连接套接字; 当工作线程运行时,它使用套接字但保持打开以便以后重用.我们决定使用这种方法,因为与临时创建,连接和销毁套接字相关的开销需要太多的开销,所以我们需要一种方法,通过这种方法,工作池预先初始化了它们的套接字连接,准备好在保持套接字资源不受其他线程影响的同时承担工作(套接字不是线程安全的),所以我们需要这些内容......

public class SocketTask implements Runnable {
  Socket socket;
  public SocketTask(){
    //create + connect socket here
  }

  public void run(){
    //use socket here
  }

}

在应用程序启动时,我们想要初始化工作程序,并希望套接字连接在某种程度上......

MyWorkerPool pool = new MyWorkerPool();
for( int i = 0; i < 100; i++)
   pool.addWorker( new WorkerThread());

当应用程序请求工作时,我们将任务发送到工作池以立即执行...

pool.queueWork( new SocketTask(..));

更新了工作代码
根据Gray和jontejj的有用评论,我有以下代码工作...

SocketTask

public class SocketTask implements Runnable {
    private String workDetails;
    private static final ThreadLocal<Socket> threadLocal = 
           new ThreadLocal<Socket>(){
        @Override
        protected Socket initialValue(){
            return new Socket();
        }           
    };

    public SocketTask(String details){              
        this.workDetails = details;
    }

    public void run(){      
        Socket s = getSocket(); //gets from threadlocal
        //send data on socket based on workDetails, etc.
    }

    public static Socket getSocket(){
        return threadLocal.get();
    }
}

ExecutorService的

ExecutorService threadPool = 
    Executors.newFixedThreadPool(5, Executors.defaultThreadFactory());

    int tasks = 15;  
    for( int i = 1; i <= tasks; i++){
        threadPool.execute(new SocketTask("foobar-" + i));
    }   

我喜欢这种方法有几个原因......

• 套接字是运行任务可用的本地对象(通过ThreadLocal),消除了并发问题.
• 套接字创建一次并保持打开状态,在新任务排队时重用,消除套接字对象创建/销毁开销.

Answer 1

一个想法是将Sockets放入BlockingQueue.然后,只要你需要一个Socket你的线程就可以take()从队列中完成,当它们完成后,Socket它们put()就会回到队列中.

public void run() {
    Socket socket = socketQueue.take();
    try {
       // use the socket ...
    } finally {
       socketQueue.put(socket);
    }
}

这有额外的好处:

• 您可以返回使用ExecutorService代码.
• 您可以将套接字通信与结果处理分开.
• 处理线程和套接字不需要一对一的对应关系.但是套接字通信可能是98%的工作,所以可能没有收获.
• 当您完成并ExecutorService完成后,您可以通过将它们出列并关闭它们来关闭套接字.

这确实增加了另一个的额外开销,BlockingQueue但如果你正在进行Socket通信,你将不会注意到它.

我们不相信ThreadFactory能满足我们的需求......

如果您使用线程本地,我认为您可以使这项工作.您的线程工厂将创建一个线程,首先打开套接字,将其存储在本地线程中,然后调用Runnablearg,它使用套接字完成所有工作,从ExecutorService内部队列中取出作业.一旦完成,该arg.run()方法将完成,您可以从线程本地获取套接字并关闭它.

像下面这样的东西.它有点乱,但你应该明白这个想法.

ExecutorService threadPool =
    Executors.newFixedThreadPool(10,
      new ThreadFactory() {
        public Thread newThread(final Runnable r) {
            Thread thread = new Thread(new Runnable() {
                public void run() {
                    openSocketAndStoreInThreadLocal();
                    // our tasks would then get the socket from the thread-local
                    r.run();
                    getSocketFromThreadLocalAndCloseIt();
                }
            });
            return thread;
        }
      }));

所以你的任务将实现Runnable 并看起来像:

public SocketWorker implements Runnable {
    private final ThreadLocal<Socket> threadLocal;
    public SocketWorker(ThreadLocal<Socket> threadLocal) {
       this.threadLocal = threadLocal;
    }
    public void run() {
        Socket socket = threadLocal.get();
        // use the socket ...
    }
}

Answer 2

我认为你应该使用ThreadLocal

package com.stackoverflow.q16680096;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class Main
{
    public static void main(String[] args)
    {
        ExecutorService pool = Executors.newCachedThreadPool();
        int nrOfConcurrentUsers = 100;
        for(int i = 0; i < nrOfConcurrentUsers; i++)
        {
            pool.submit(new InitSocketTask());
        }

        // do stuff...

        pool.submit(new Task());
    }
}

package com.stackoverflow.q16680096;

import java.net.Socket;

public class InitSocketTask implements Runnable
{
    public void run()
    {
        Socket socket = SocketPool.get();
        // Do initial setup here
    }

}

package com.stackoverflow.q16680096;

import java.net.Socket;

public final class SocketPool
{
    private static final ThreadLocal<Socket> SOCKETS = new ThreadLocal<Socket>(){
        @Override
        protected Socket initialValue()
        {
            return new Socket(); // Pass in suitable arguments here...
        }
    };

    public static Socket get()
    {
        return SOCKETS.get();
    }
}

package com.stackoverflow.q16680096;

import java.net.Socket;

public class Task implements Runnable
{
    public void run()
    {
        Socket socket = SocketPool.get();
        // Do stuff with socket...
    }
}

每个线程都有自己的套接字.