关于多线程安全和Socket堵塞

[ArLi2003]

我只一个用户名，所以没有可用分转让之类的东东，没分了，所以本贴只有10分，原谅原谅

不少人在多线程上误解挺深的，我举个例子总结一下吧，算上版主上任第一篇谢贴：

class a:
lock (a){
//code
lock(b){
//code
}
}

class b:

lock (b){
//code
lock(a){
//code
}
}

假若，上面二个线程任意一个出现中止或挂起，将导致二个线程都死锁，永久进入睡眠状态。因为他们都在等待对方解锁。

这是一个比较容易犯的错误，这也是为什么thread.abort 要抛出异常的原因，目的就是让你知道线程异常中止，要你自己注意是否有要善后的处理。不少的贴子我都有警告过，必须要设置一个公用变量数组（推荐使用sortlist 之类的二维表），在各线程的while 内部去判断是否线程应该中止！


有些朋友提到了碰到了socket 堵塞式多线程怎么办？其实不然，那其实是你的编程误区，socket 的AcceptSocket 应该这样写（取自我过去写的sock 聊天程序）：

while (cls_Const.ListenStartMode) {
if (!listener.Pending()) {
Thread.Sleep(cls_Const.ListenThreadSleep);
}
else if (!cls_Const.ServiceStartMode) {
Socket sockServer = listener.AcceptSocket();
...
}

相信cls_Const.ListenStartMode 你应该知道是什么用吧，就是控制线程是否继续运行的变量
而 cls_Const.ListenThreadSleep 是负责睡眠时间也就是socket 接受请求的间隔，目的只是为了保证CPU 在while 体内 不会跑到100%

最后要补充的是要注意定义：

sockServer.SetSocketOption(
SocketOptionLevel.Socket,
SocketOptionName.ReceiveTimeout,
cls_Const.revSockTimeOut
);

sockServer.SetSocketOption(
SocketOptionLevel.Socket,
SocketOptionName.SendTimeout,
cls_Const.sendSockTimeOut
);

里面的timeout 我想应该是知道什么意思吧，就是超时的毫秒

[ArLi2003]

关于多线程的内容，引自：
http://expert.csdn.net/Expert/TopicView1.asp?id=1905252

socket 是补充内容，引自：
http://expert.csdn.net/Expert/TopicView1.asp?id=1906711

有不同意见的兄弟来补充一下

[ArLi2003]

我的其中一个类，写的比较早，算法上不够先进别怪我：

using System;
using System.Net;
using System.Net.Sockets;
using System.Threading;
using System.Text;

namespace ArLi.xChat.Server
{
public class cls_Listen
{
private fm_Server fm_Server;
public TcpListener listener = new TcpListener(cls_Const.sockPort);

public cls_Listen(fm_Server Obj)
{
fm_Server = Obj;
fm_Server.stBar_myIP.Text = Dns.GetHostByName(Dns.GetHostName()).AddressList[0].ToString();
}

private void endSock(Socket sockServer){
sockServer.Shutdown(SocketShutdown.Both);
sockServer.Close();
sockServer = null;
}

private string getUserName(Socket sockServer){
try{
byte[] recvBytes = new byte[cls_Const.sockBuffer];
int getByteLen = 0;
if (sockServer.Connected) {
getByteLen = sockServer.Receive(recvBytes,recvBytes.Length,0);
}
byte[] byteBody = new byte[getByteLen];
Array.Copy(recvBytes,0,byteBody,0,getByteLen);

string myStr = Encoding.Default.GetString(byteBody);

if (myStr.Length >4 && myStr.Substring(0,3) == "un@"){
myStr = myStr.Substring(3,myStr.Length -3);
myStr = myStr.ToLower().Trim();

if (myStr.Length < 3) {
byteBody = Encoding.Default.GetBytes("Sorry@name too short, try other name!!");
sockServer.Send(byteBody,byteBody.Length,0);
this.endSock(sockServer);
return null;
}
else if (myStr.Length > 20){
byteBody = Encoding.Default.GetBytes("Sorry@name max length 20 char, try other name!!");
sockServer.Send(byteBody,byteBody.Length,0);
this.endSock(sockServer);
return null;
}
else if (myStr.IndexOf("@")>=0) {
byteBody = Encoding.Default.GetBytes("Sorry@name can't use @ , remove @ try again!!");
sockServer.Send(byteBody,byteBody.Length,0);
this.endSock(sockServer);
return null;
}
else if (fm_Server.lstBox_UserList.Items.Contains(myStr)){
byteBody = Encoding.Default.GetBytes("Sorry@name:" + myStr + " exist in server, try other name!!");
sockServer.Send(byteBody,byteBody.Length,0);
this.endSock(sockServer);
return null;
}
else{
return myStr;
}
}
else{
return null;
}
}catch{
return null;
}
}

public void goListen(){

listener.Start();
fm_Server.AddLog("Thread Start .. wait service start ..",null);

while (cls_Const.ListenStartMode) {

if (fm_Server.chk_StartServer.Checked && cls_Const.ThreadCountNow > cls_Const.ThreadMax) {
fm_Server.AddLog("Thread Max .. Stop Service ..",null);
fm_Server.chk_StartServer.Checked = false;
}

if (!listener.Pending()) {
Thread.Sleep(cls_Const.ListenThreadSleep);
}
else if (!cls_Const.ServiceStartMode) {
Socket sockServer = listener.AcceptSocket();
byte[] strTmp = Encoding.Default.GetBytes(cls_Const.ServiceStopModeMessage);
sockServer.Send(strTmp,strTmp.Length,0);
sockServer.Shutdown(SocketShutdown.Both);
sockServer.Close();
sockServer = null;
}
else{
Socket sockServer = listener.AcceptSocket();

sockServer.SetSocketOption(
SocketOptionLevel.Socket,
SocketOptionName.ReceiveTimeout,
cls_Const.revSockTimeOut
);

sockServer.SetSocketOption(
SocketOptionLevel.Socket,
SocketOptionName.SendTimeout,
cls_Const.sendSockTimeOut
);

sockServer.Send(Encoding.Default.GetBytes(cls_Const.GlobalWelcome));

string newUserName = getUserName(sockServer);

if (newUserName == null){
if (sockServer != null && sockServer.Connected) {
byte[] strTmp = Encoding.Default.GetBytes("must input username! format of: un@myNiceName");
sockServer.Send(strTmp,strTmp.Length,0);
sockServer.Shutdown(SocketShutdown.Both);
sockServer.Close();
sockServer = null;
}
}
else{

object[] ObjTmp = new object[cls_Const.ThreadProFormatUpper];
ObjTmp[(int)cls_Const.ThreadProFormat.Name] = newUserName;
ObjTmp[(int)cls_Const.ThreadProFormat.IP] = sockServer.RemoteEndPoint;
ObjTmp[(int)cls_Const.ThreadProFormat.Time] = DateTime.Now;
ObjTmp[(int)cls_Const.ThreadProFormat.SockObj] = sockServer;

int onRevID;
if (cls_Const.arr_FreeThreadProTable.Count == 0){
lock(cls_Const.arr_ThreadProTable){

cls_Const.arr_ThreadProTable.Add(ObjTmp);
fm_Server.lstBox_UserList.Items.Add(newUserName);

onRevID = cls_Const.arr_ThreadProTable.Count -1;
}
}else{
lock(cls_Const.arr_FreeThreadProTable){
onRevID = (int)cls_Const.arr_FreeThreadProTable[0];

cls_Const.arr_ThreadProTable[onRevID] = ObjTmp;
fm_Server.lstBox_UserList.Items[onRevID] = newUserName;

cls_Const.arr_FreeThreadProTable.RemoveAt(0);
}
}

fm_Server.AddLog(ObjTmp[1].ToString() + "/" + ((DateTime)ObjTmp[2]).ToString("t") + " Join.",null);
fm_Server.newThreadRev(onRevID);
}
}
}

listener.Stop();
listener = null;
}
}
}

[cmsoft]

study~~

[IceboundRock]

兄台的代码写的……怎么没有一行注释啊……

[ArLi2003]

是啊是啊，所以我一开始也不敢放出来，其实重要的是：

if (!listener.Pending()) {

用处是检测当前socket 请求队列中有没有等待的，如果没有就睡觉

[qimini]

up

[YJ123]

谢谢！！！学习ing!!!

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[RnfShadow]

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