Question

在运行使用消费者/生产者设计创建的套接字服务器时出现此问题，程序在日志中崩溃并显示错误cpu time limit exceeded。我还发现当时cpu的使用量超过90%。这是服务器的代码，可能出现什么问题以及如何优化它？

我使用这种queue方法来避免为每个请求创建这么多threads。

主方法（主线程）

//holds socket instances
ConcurrentLinkedQueue<Socket> queue = new ConcurrentLinkedQueue<>();

//create producer thread
Thread producer = new Thread(new RequestProducer(queue));
//create consumer thread
Thread consumer = new Thread(new RequestConsumer(queue));

producer.start();
consumer.start();

RequestProducer线程

//this holds queue instance coming from main thread
ConcurrentLinkedQueue<Socket> queue

//constructor, initiate queue
public RequestProducer(
    ConcurrentLinkedQueue<Socket> queue
) {
    this.queue = queue;
}

public void run() {
    try {
        //create serversocket instance on port 19029
        ServerSocket serverSocket = new ServerSocket(19029);
        while (true) {
            try {
                //keep accept connections
                Socket socket = serverSocket.accept();
                //add socket to queue
                queue.offer(socket);
            } catch (ConnectException ce) {//handle exception
            } catch (SocketException e) {//handle exception
            }
        }
    } catch (IOException ex) {//handle exception}
}

RequestConsumer线程

//this holds queue instance coming from main thread, same as requestproducer
ConcurrentLinkedQueue<Socket> queue

//constructor, initiate queue
public RequestConsumer(
    ConcurrentLinkedQueue<Socket> queue
) {
    this.queue = queue;
}

public void run() {
    try {
        Socket socket = null;
        while (true) {
            //get head of the queue (socket instance)
            socket = queue.poll();
            if (null != socket) {
                //process data stream
                String in = DataStreamUtil.parseAsciiSockStream(socket.getInputStream());
                //close socket conection
                socket.close();
                //excecute database insert of processed data
                excecuteDbInsert(in);
            }
        }
    } catch (IOException | ParseException ex) {//handle exceptions}
}

数据流解析器

public static String parseAsciiSockStream(InputStream in) throws IOException {
    StringBuilder builder = new StringBuilder();
    if (null != in) {
        byte[] b = new byte[BYTE_STREAM_MAX];
        int length = in.read(b);
        for (int i = 0; i < length; i++) {
            builder.append((char) (int) b[i]);
        }
        in.close();
    }
    return builder.toString();
}

Answer 1

由于您的消费者积极while(true)循环，超出了CPU时间限制。下面是一个如何解决问题的例子。

您可以在while循环中将简单Thread.sleep(1)添加到Consumer中，或使用wait / notify模式来限制CPU消耗。

RequestProducer线程

import java.io.IOException;
import java.net.ConnectException;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.SocketException;
import java.util.concurrent.ConcurrentLinkedQueue;

public class RequestProducer implements Runnable {
    //this holds queue instance coming from main thread
    final ConcurrentLinkedQueue<Socket> queue;

    //constructor, initiate queue
    public RequestProducer(
            ConcurrentLinkedQueue<Socket> queue
    ) {
        this.queue = queue;
    }

    public void run() {
        try {
            //create serversocket instance on port 19029
            ServerSocket serverSocket = new ServerSocket(19029);
            while (true) {
                try {
                    //keep accept connections
                    Socket socket = serverSocket.accept();
                    //add socket to queue
                    queue.offer(socket);
                    synchronized (queue) {
                        System.out.println("notifying");
                        queue.notify();
                    }
                } catch (ConnectException ce) {//handle exception
                } catch (SocketException e) {//handle exception
                }
            }
        } catch (IOException ex) {//handle exception}
        }

    }
}

RequestConsumer线程

import java.io.IOException;
import java.net.Socket;
import java.text.ParseException;
import java.util.concurrent.ConcurrentLinkedQueue;

public class RequestConsumer implements Runnable {
    //this holds queue instance coming from main thread, same as requestproducer
    final ConcurrentLinkedQueue<Socket> queue;

    //constructor, initiate queue
    public RequestConsumer(
            ConcurrentLinkedQueue<Socket> queue
    ) {
        this.queue = queue;
    }

    public void run() {
        try {
            Socket socket = null;
            while (true) {
                //get head of the queue (socket instance)
                System.out.println("Waiting for new socket");
                synchronized (queue) {
                    queue.wait();
                }
                System.out.println("Acquired new socket");

                socket = queue.poll();
                try {
                    if (null != socket) {
                        //process data stream
                        String in = DataStreamUtil.parseAsciiSockStream(socket.getInputStream());
                        //close socket conection
                        socket.close();
                        //excecute database insert of processed data
                        //excecuteDbInsert(in);

                        System.out.println(in);
                    }
                } finally {
                    if (socket != null) {
                        socket.close();
                    }
                }

            }
        } catch (IOException ex) {//handle exceptions}
        } catch (InterruptedException e) {
            e.printStackTrace();
            Thread.currentThread().interrupt();
        }
    }

}

数据流解析器

import java.io.IOException;
import java.io.InputStream;

public class DataStreamUtil {
    public static String parseAsciiSockStream(InputStream in) throws IOException {
        StringBuilder builder = new StringBuilder();
        if (null != in) {
            byte[] b = new byte[BYTE_STREAM_MAX];
            System.out.println("Waiting for input");
            int length = in.read(b);
            System.out.println("Got input");
            for (int i = 0; i < length; i++) {
                builder.append((char) (int) b[i]);
            }
            in.close();
        }
        return builder.toString();
    }
}

消费者 - 生产者设计'超出CPU时间限制'的TCP套接字服务器

1 个答案: