Java 多线程服务器 - 高 CPU 利用率和 java.net.SocketException：套接字已关闭
Java multithreaded server - High CPU Utilization and java.net.SocketException: socket closed
这是我编写的第一个 java socket/multithreaded 应用程序，因此对于您即将看到的残暴代码，我深表歉意。
无论如何，你们中的大多数人可能会认为这段代码是基本的，一个允许更多客户端同时连接的标准服务器。此外，服务器有一个只有一个 StopServer 按钮的界面，该按钮关闭服务器，同时客户端除了连接到服务器然后断开连接之外什么都不做。
现在，如果我只是 运行 服务器 class，没关系，没有任何 'bad' 发生，当我关闭它时，它关闭正常，但是：
1：如果我运行服务器class，然后我运行客户端class一次，让客户端断开连接，然后然后尝试关闭服务器，我得到错误：
java.net.SocketException: socket closed
2：每个客户端将在短暂的 运行 内增加约 30-35% 的 CPU 利用率，并且该利用率将保持在 "Java(TM) Platform SE Binary" 进程，只要服务器继续 运行。如果我让客户端连接到服务器，比方说 30 秒，CPU 利用率将达到 100%。
另外，我做了一点研究，我知道 "socket closed exception" 意味着你关闭了套接字，然后继续尝试使用它，而且服务器处理的方式也可能有问题断开连接的客户端。
代码如下：
服务器
import java.sql.*;
import java.net.*;
import java.io.*;
import java.util.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Server extends JFrame
{ private Connection con;
private static int port = 44444;
private boolean serverKeepGoing;
private static int uniqueId;
private ArrayList<ClientThread> al;
private ServerSocket serverSocket;
public Scanner keyboard = new Scanner(System.in);
public static void main(String[] args) throws IOException
{ Server server = new Server(port);
server.start();
}
public void ServerClose()
{
serverKeepGoing = false;
try
{
for(int i = 0; i < al.size(); ++i)
{ ClientThread tc = al.get(i);
try
{
tc.in.close();
tc.out.close();
tc.socket.close(); }
catch(IOException e) { e.printStackTrace(); }
serverSocket.close();}
}catch(Exception e) { e.printStackTrace(); }
}
public Server (int port)
{
serverInterface();
al = new ArrayList<ClientThread>();
}
public void start()
{ serverKeepGoing = true;
try
{ serverSocket = new ServerSocket(port);
System.out.println("Server is running!");
while(serverKeepGoing)
{ Socket socket = serverSocket.accept(); // accept connection. LINE 65
// ^ALSO :java.net.SocketException: socket closed
// if I was asked to stop
if(!serverKeepGoing)
{ ServerClose(); break;}
ClientThread t = new ClientThread(socket); // make a thread of it
al.add(t); // save it in the ArrayList
t.start();
}
ServerClose(); // means the server has got to be closed
}catch (IOException e) { e.printStackTrace(); System.out.println("Error in method start"); }
}
public synchronized void remove(int id) {
// scan the array list until we found the Id
for(int i = 0; i < al.size(); ++i) {
ClientThread ct = al.get(i);
// found it
if(ct.id == id) {
al.remove(i);
return;
}
}
}
class ClientThread extends Thread
{ // the socket where to listen/talk
Socket socket;
BufferedReader in;
PrintWriter out;
boolean clientKeepGoing;
// my unique id (easier for deconnection)
int id;
public ClientThread(Socket socket)
{ id = ++uniqueId;
this.socket = socket;
try
{
in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
out = new PrintWriter(socket.getOutputStream(), true);
}
catch (IOException e) { return; }
}
public void run()
{
boolean clientKeepGoing = true;
while(clientKeepGoing)
{ try
{
}catch(Exception e){ e.printStackTrace(); }
}
// remove myself from the arrayList containing the list of the
// connected Clients
remove(id);
close();
}
// try to close everything
private void close()
{ clientKeepGoing = false;
try {
if(out != null) out.close();
}
catch(Exception e) {}
try {
if(in != null) in.close();
}
catch(Exception e) {};
try {
if(socket != null) socket.close();
}
catch (Exception e) {}
}
}
public void serverInterface(){
JFrame frame = new JFrame("Server");
frame.setLayout(null);
int windowWidth = 300;
int windowHeight = 400;
frame.setBounds(250, 150, windowWidth, windowHeight);
JButton stopServer = new JButton("Stop server");
stopServer.setFocusable(false);
stopServer.setBounds(60, 275, 175, 20);
frame.add(stopServer);
stopServer.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e)
{
ServerClose();
System.exit(1);
}
});
frame.setResizable(false);
frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
frame.setVisible(true);
}
public void windowClosing(WindowEvent e)
{ ServerClose();
System.exit(1);
}
public void windowClosed(WindowEvent e) {}
public void windowOpened(WindowEvent e) {}
public void windowIconified(WindowEvent e) {}
public void windowDeiconified(WindowEvent e) {}
public void windowActivated(WindowEvent e) {}
public void windowDeactivated(WindowEvent e) {}
}
'java.net.SocketException: socket closed' 在上面代码的第 65 行。
客户端
import java.net.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.util.*;
import javax.swing.*;
public class Client
{ private BufferedReader in;
private PrintWriter out;
private Socket socket;
private int port;
private String server;
public static void main(String[] args)
{ int portNumber = 44444;
String serverAddress = "localhost";
Client client = new Client(serverAddress, portNumber);
if(!client.start())
return;
}
public Client(String server, int port)
{ this.server = server;
this.port = port;
}
public boolean start()
{ // try to connect to the server
try {
socket = new Socket(server, port);
}
// if it failed not much I can do
catch(Exception ec) {
System.out.println("Error connectiong to server:" + ec);
ec.printStackTrace();
return false;
}
try
{
in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
out = new PrintWriter(socket.getOutputStream(), true);;
}
catch (IOException eIO) {
System.out.println("Exception creating new Input/output Streams: " + eIO);
eIO.printStackTrace();
return false;
}
// creates the Thread to listen from the server
new ListenFromServer().start();
// success we inform the caller that it worked
return true;
}
class ListenFromServer extends Thread
{
public void run()
{ while(true)
{
disconnect() ;
break;
}
}
}
public void disconnect()
{ try {
if(in != null) in.close();
}
catch(Exception e) {} // not much else I can do
try {
if(out != null) out.close();
}
catch(Exception e) {} // not much else I can do
try{
if(socket != null) socket.close();
}
catch(Exception e) {} // not much else I can do
}
}
请注意，这只是我当前正在构建的整个应用程序的一个片段，我试图 post 仅与服务器-客户端通信有关，所以我删除了其他所有内容，我'我这么说是为了防止你看到一些可能没有任何目的的东西，我可能会忘记删除它
我看到问题被标记为重复，我认为这是不公平的。首先，在 'similar' 问题中，问题很明显，outpot流被关闭，从而关闭了套接字，但套接字仍在使用，同时，我的程序将所有内容全部关闭，并且还有 CPU 我提到的问题，我无法从所谓的 'similar' 问题中得到任何答案。
高 CPU 利用率是因为您的客户端线程除了用它们的空循环燃烧 CPU 之外没有做任何其他事情。至于SocketException，按计划进行，抓起来处理。
这是我编写的第一个 java socket/multithreaded 应用程序，因此对于您即将看到的残暴代码，我深表歉意。
无论如何，你们中的大多数人可能会认为这段代码是基本的，一个允许更多客户端同时连接的标准服务器。此外，服务器有一个只有一个 StopServer 按钮的界面，该按钮关闭服务器，同时客户端除了连接到服务器然后断开连接之外什么都不做。
现在，如果我只是 运行 服务器 class，没关系，没有任何 'bad' 发生，当我关闭它时，它关闭正常，但是：
1：如果我运行服务器class，然后我运行客户端class一次，让客户端断开连接，然后然后尝试关闭服务器，我得到错误：
java.net.SocketException: socket closed
2：每个客户端将在短暂的 运行 内增加约 30-35% 的 CPU 利用率，并且该利用率将保持在 "Java(TM) Platform SE Binary" 进程，只要服务器继续 运行。如果我让客户端连接到服务器，比方说 30 秒，CPU 利用率将达到 100%。
另外，我做了一点研究，我知道 "socket closed exception" 意味着你关闭了套接字，然后继续尝试使用它，而且服务器处理的方式也可能有问题断开连接的客户端。
代码如下：
服务器
import java.sql.*;
import java.net.*;
import java.io.*;
import java.util.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Server extends JFrame
{ private Connection con;
private static int port = 44444;
private boolean serverKeepGoing;
private static int uniqueId;
private ArrayList<ClientThread> al;
private ServerSocket serverSocket;
public Scanner keyboard = new Scanner(System.in);
public static void main(String[] args) throws IOException
{ Server server = new Server(port);
server.start();
}
public void ServerClose()
{
serverKeepGoing = false;
try
{
for(int i = 0; i < al.size(); ++i)
{ ClientThread tc = al.get(i);
try
{
tc.in.close();
tc.out.close();
tc.socket.close(); }
catch(IOException e) { e.printStackTrace(); }
serverSocket.close();}
}catch(Exception e) { e.printStackTrace(); }
}
public Server (int port)
{
serverInterface();
al = new ArrayList<ClientThread>();
}
public void start()
{ serverKeepGoing = true;
try
{ serverSocket = new ServerSocket(port);
System.out.println("Server is running!");
while(serverKeepGoing)
{ Socket socket = serverSocket.accept(); // accept connection. LINE 65
// ^ALSO :java.net.SocketException: socket closed
// if I was asked to stop
if(!serverKeepGoing)
{ ServerClose(); break;}
ClientThread t = new ClientThread(socket); // make a thread of it
al.add(t); // save it in the ArrayList
t.start();
}
ServerClose(); // means the server has got to be closed
}catch (IOException e) { e.printStackTrace(); System.out.println("Error in method start"); }
}
public synchronized void remove(int id) {
// scan the array list until we found the Id
for(int i = 0; i < al.size(); ++i) {
ClientThread ct = al.get(i);
// found it
if(ct.id == id) {
al.remove(i);
return;
}
}
}
class ClientThread extends Thread
{ // the socket where to listen/talk
Socket socket;
BufferedReader in;
PrintWriter out;
boolean clientKeepGoing;
// my unique id (easier for deconnection)
int id;
public ClientThread(Socket socket)
{ id = ++uniqueId;
this.socket = socket;
try
{
in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
out = new PrintWriter(socket.getOutputStream(), true);
}
catch (IOException e) { return; }
}
public void run()
{
boolean clientKeepGoing = true;
while(clientKeepGoing)
{ try
{
}catch(Exception e){ e.printStackTrace(); }
}
// remove myself from the arrayList containing the list of the
// connected Clients
remove(id);
close();
}
// try to close everything
private void close()
{ clientKeepGoing = false;
try {
if(out != null) out.close();
}
catch(Exception e) {}
try {
if(in != null) in.close();
}
catch(Exception e) {};
try {
if(socket != null) socket.close();
}
catch (Exception e) {}
}
}
public void serverInterface(){
JFrame frame = new JFrame("Server");
frame.setLayout(null);
int windowWidth = 300;
int windowHeight = 400;
frame.setBounds(250, 150, windowWidth, windowHeight);
JButton stopServer = new JButton("Stop server");
stopServer.setFocusable(false);
stopServer.setBounds(60, 275, 175, 20);
frame.add(stopServer);
stopServer.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e)
{
ServerClose();
System.exit(1);
}
});
frame.setResizable(false);
frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
frame.setVisible(true);
}
public void windowClosing(WindowEvent e)
{ ServerClose();
System.exit(1);
}
public void windowClosed(WindowEvent e) {}
public void windowOpened(WindowEvent e) {}
public void windowIconified(WindowEvent e) {}
public void windowDeiconified(WindowEvent e) {}
public void windowActivated(WindowEvent e) {}
public void windowDeactivated(WindowEvent e) {}
}
'java.net.SocketException: socket closed' 在上面代码的第 65 行。
客户端
import java.net.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.util.*;
import javax.swing.*;
public class Client
{ private BufferedReader in;
private PrintWriter out;
private Socket socket;
private int port;
private String server;
public static void main(String[] args)
{ int portNumber = 44444;
String serverAddress = "localhost";
Client client = new Client(serverAddress, portNumber);
if(!client.start())
return;
}
public Client(String server, int port)
{ this.server = server;
this.port = port;
}
public boolean start()
{ // try to connect to the server
try {
socket = new Socket(server, port);
}
// if it failed not much I can do
catch(Exception ec) {
System.out.println("Error connectiong to server:" + ec);
ec.printStackTrace();
return false;
}
try
{
in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
out = new PrintWriter(socket.getOutputStream(), true);;
}
catch (IOException eIO) {
System.out.println("Exception creating new Input/output Streams: " + eIO);
eIO.printStackTrace();
return false;
}
// creates the Thread to listen from the server
new ListenFromServer().start();
// success we inform the caller that it worked
return true;
}
class ListenFromServer extends Thread
{
public void run()
{ while(true)
{
disconnect() ;
break;
}
}
}
public void disconnect()
{ try {
if(in != null) in.close();
}
catch(Exception e) {} // not much else I can do
try {
if(out != null) out.close();
}
catch(Exception e) {} // not much else I can do
try{
if(socket != null) socket.close();
}
catch(Exception e) {} // not much else I can do
}
}
请注意，这只是我当前正在构建的整个应用程序的一个片段，我试图 post 仅与服务器-客户端通信有关，所以我删除了其他所有内容，我'我这么说是为了防止你看到一些可能没有任何目的的东西，我可能会忘记删除它
我看到问题被标记为重复，我认为这是不公平的。首先，在 'similar' 问题中，问题很明显，outpot流被关闭，从而关闭了套接字，但套接字仍在使用，同时，我的程序将所有内容全部关闭，并且还有 CPU 我提到的问题，我无法从所谓的 'similar' 问题中得到任何答案。
高 CPU 利用率是因为您的客户端线程除了用它们的空循环燃烧 CPU 之外没有做任何其他事情。至于SocketException，按计划进行，抓起来处理。