介绍
一次简单的Socket探索之旅，分别对Socket服务端的两种方式进行了测试和解析。
CommonSocket
代码实现
实现一个简单的Socket服务，基本功能就是接收消息然后加上结束消息时间返回给客户端。
/// <summary>
/// 简单服务，收发消息
/// </summary>
class FirstSimpleServer
{
public static void Run(string m_ip, int m_port)
{
var socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
var ip = IPAddress.Parse(m_ip);
var endpoint = new IPEndPoint(ip, m_port);
socket.Bind(endpoint);
socket.Listen(0);
socket.ReceiveTimeout = -1;
Task.Run(() =>
{
while (true)
{
var acceptSocket = socket.Accept();
if (acceptSocket != null && acceptSocket.Connected)
{
Task.Run(() =>
{
byte[] receiveBuffer = new byte[256];
int result = 0;
do
{
if (acceptSocket.Connected)
{
result = acceptSocket.Receive(receiveBuffer, 0, receiveBuffer.Length,
SocketFlags.None,
out SocketError error);
if (error == SocketError.Success && result > 0)
{
var recestr = Encoding.UTF8.GetString(receiveBuffer, 0, result);
var Replaystr =
$"Server收到消息:{recestr};Server收到消息的时间:{DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss:fff")}";
Console.WriteLine(Replaystr);
var strbytes = Encoding.UTF8.GetBytes(Replaystr);
acceptSocket.Send(strbytes, 0, strbytes.Length, SocketFlags.None);
if (recestr.Contains("stop"))
{
break;
}
}
}
else
{
break;
}
} while (result > 0);
}).ContinueWith((t) =>
{
System.Threading.Thread.Sleep(1000);
acceptSocket.Disconnect(false);
acceptSocket.Dispose();
});
}
}
}).Wait();
}
简单测试
测试：一个客户端，发送10次数据，每次间隔50ms，
结果：客户端的显示如下，客户端发送消息，再接收到，十次中最长的耗时10ms。
ClientReceiceServer:{Server收到消息:{Client:1:MessageID:0;Client发送时间:2020-04-11 13:21:22:974};Server收到消息的时间:2020-04-11 13:21:22:981;ClientReceiceServer时间:2020-04-11 13:21:22:984}
ClientReceiceServer:{Server收到消息:{Client:1:MessageID:1;Client发送时间:2020-04-11 13:21:23:032};Server收到消息的时间:2020-04-11 13:21:23:032;ClientReceiceServer时间:2020-04-11 13:21:23:032}
ClientReceiceServer:{Server收到消息:{Client:1:MessageID:2;Client发送时间:2020-04-11 13:21:23:082};Server收到消息的时间:2020-04-11 13:21:23:082;ClientReceiceServer时间:2020-04-11 13:21:23:083}
ClientReceiceServer:{Server收到消息:{Client:1:MessageID:3;Client发送时间:2020-04-11 13:21:23:133};Server收到消息的时间:2020-04-11 13:21:23:133;ClientReceiceServer时间:2020-04-11 13:21:23:133}
ClientReceiceServer:{Server收到消息:{Client:1:MessageID:4;Client发送时间:2020-04-11 13:21:23:184};Server收到消息的时间:2020-04-11 13:21:23:184;ClientReceiceServer时间:2020-04-11 13:21:23:190}
ClientReceiceServer:{Server收到消息:{Client:1:MessageID:5;Client发送时间:2020-04-11 13:21:23:235};Server收到消息的时间:2020-04-11 13:21:23:235;ClientReceiceServer时间:2020-04-11 13:21:23:235}
ClientReceiceServer:{Server收到消息:{Client:1:MessageID:6;Client发送时间:2020-04-11 13:21:23:286};Server收到消息的时间:2020-04-11 13:21:23:286;ClientReceiceServer时间:2020-04-11 13:21:23:286}
ClientReceiceServer:{Server收到消息:{Client:1:MessageID:7;Client发送时间:2020-04-11 13:21:23:336};Server收到消息的时间:2020-04-11 13:21:23:336;ClientReceiceServer时间:2020-04-11 13:21:23:336}
ClientReceiceServer:{Server收到消息:{Client:1:MessageID:8;Client发送时间:2020-04-11 13:21:23:387};Server收到消息的时间:2020-04-11 13:21:23:387;ClientReceiceServer时间:2020-04-11 13:21:23:388}
ClientReceiceServer:{Server收到消息:{Client:1:MessageID:9;Client发送时间:2020-04-11 13:21:23:438};Server收到消息的时间:2020-04-11 13:21:23:438;ClientReceiceServer时间:2020-04-11 13:21:23:438}
假如客户端发送消息速度加快，对服务端会有什么影响？测试将客户端发送消息的间隔修改为1ms
System.Threading.Thread.Sleep(1);
结果如下,并没有发现问题。
ClientReceiceServer:{Server收到消息:{Client:1:MessageID:0;Client发送时间:2020-04-11 13:48:57:193};Server收到消息的时间:2020-04-11 13:48:57:196;ClientReceiceServer时间:2020-04-11 13:48:57:197}
ClientReceiceServer:{Server收到消息:{Client:1:MessageID:1;Client发送时间:2020-04-11 13:48:57:198};Server收到消息的时间:2020-04-11 13:48:57:198;ClientReceiceServer时间:2020-04-11 13:48:57:201}
ClientReceiceServer:{Server收到消息:{Client:1:MessageID:2;Client发送时间:2020-04-11 13:48:57:200};Server收到消息的时间:2020-04-11 13:48:57:201;ClientReceiceServer时间:2020-04-11 13:48:57:202}
ClientReceiceServer:{Server收到消息:{Client:1:MessageID:3;Client发送时间:2020-04-11 13:48:57:202};Server收到消息的时间:2020-04-11 13:48:57:202;ClientReceiceServer时间:2020-04-11 13:48:57:203}
ClientReceiceServer:{Server收到消息:{Client:1:MessageID:4;Client发送时间:2020-04-11 13:48:57:204};Server收到消息的时间:2020-04-11 13:48:57:204;ClientReceiceServer时间:2020-04-11 13:48:57:204}
ClientReceiceServer:{Server收到消息:{Client:1:MessageID:5;Client发送时间:2020-04-11 13:48:57:206};Server收到消息的时间:2020-04-11 13:48:57:206;ClientReceiceServer时间:2020-04-11 13:48:57:207}
ClientReceiceServer:{Server收到消息:{Client:1:MessageID:6;Client发送时间:2020-04-11 13:48:57:208};Server收到消息的时间:2020-04-11 13:48:57:208;ClientReceiceServer时间:2020-04-11 13:48:57:208}
ClientReceiceServer:{Server收到消息:{Client:1:MessageID:7;Client发送时间:2020-04-11 13:48:57:209};Server收到消息的时间:2020-04-11 13:48:57:209;ClientReceiceServer时间:2020-04-11 13:48:57:211}
ClientReceiceServer:{Server收到消息:{Client:1:MessageID:8;Client发送时间:2020-04-11 13:48:57:211};Server收到消息的时间:2020-04-11 13:48:57:211;ClientReceiceServer时间:2020-04-11 13:48:57:212}
ClientReceiceServer:{Server收到消息:{Client:1:MessageID:9;Client发送时间:2020-04-11 13:48:57:213};Server收到消息的时间:2020-04-11 13:48:57:213;ClientReceiceServer时间:2020-04-11 13:48:57:213}
再极致一点，将客户端的发送间隔取消，循环发送。看到下面服务端接收消息的结果，可看到消息包很混乱。仔细分析一下，发现其实服务器其实就收到3次消息，前两次接受256个字节，最后一次接收138字节。这是由于设置服务端接收缓存的大小为256个字节。说明发送比较快或并行发送的时候，服务端会很快将接收的缓存块填满，一旦填满，Receive方法就会返回，不然就处于阻塞状态。
Server收到消息:{Client:1:MessageID:1;Client发送时间:2020-04-11 13:51:18:723}{Client:1:MessageID:2;Client发送时间:2020-04-11 13:51:18:724}{Client:1:MessageID:3;Client发送时间:2020-04-11 13:51:18:724}{Client:1:MessageID:4;Client发送时间:2020-04-11 13:51:18:;Server收到消息的时间:2020-04-11 13:51:18:724
Server收到消息:724}{Client:1:MessageID:5;Client发送时间:2020-04-11 13:51:18:724}{Client:1:MessageID:6;Client发送时间:2020-04-11 13:51:18:724}{Client:1:MessageID:7;Client发送时间:2020-04-11 13:51:18:724}{Client:1:MessageID:8;Client发送时间:2020-04-11 13:51;Server收到消息的时间:2020-04-11 13:51:18:729
Server收到消息::18:724}{Client:1:MessageID:9;Client发送时间:2020-04-11 13:51:18:724};Server收到消息的时间:2020-04-11 13:51:18:732
通过一个简单的方法解决这个问题，每次客户端发送固定长度的消息，服务端接收固定长度的消息。现在客户端发送的消息是65个字节，设置服务端接收数据的缓存块为65字节。
{Client:1:MessageID:1;Client发送时间:2020-04-11 13:51:18:723}
byte[] receiveBuffer = new byte[65];
再连续发送10条消息，下面为服务端测试的结果，结果显示正常：
Server收到消息:{Client:1:MessageID:0;Client发送时间:2020-04-11 14:19:44:774};Server收到消息的时间:2020-04-11 14:19:44:778
Server收到消息:{Client:1:MessageID:1;Client发送时间:2020-04-11 14:19:44:776};Server收到消息的时间:2020-04-11 14:19:44:781
Server收到消息:{Client:1:MessageID:2;Client发送时间:2020-04-11 14:19:44:776};Server收到消息的时间:2020-04-11 14:19:44:781
Server收到消息:{Client:1:MessageID:3;Client发送时间:2020-04-11 14:19:44:776};Server收到消息的时间:2020-04-11 14:19:44:782
Server收到消息:{Client:1:MessageID:4;Client发送时间:2020-04-11 14:19:44:776};Server收到消息的时间:2020-04-11 14:19:44:782
Server收到消息:{Client:1:MessageID:5;Client发送时间:2020-04-11 14:19:44:776};Server收到消息的时间:2020-04-11 14:19:44:782
Server收到消息:{Client:1:MessageID:6;Client发送时间:2020-04-11 14:19:44:776};Server收到消息的时间:2020-04-11 14:19:44:783
Server收到消息:{Client:1:MessageID:7;Client发送时间:2020-04-11 14:19:44:776};Server收到消息的时间:2020-04-11 14:19:44:783
Server收到消息:{Client:1:MessageID:8;Client发送时间:2020-04-11 14:19:44:776};Server收到消息的时间:2020-04-11 14:19:44:784
Server收到消息:{Client:1:MessageID:9;Client发送时间:2020-04-11 14:19:44:776};Server收到消息的时间:2020-04-11 14:19:44:784
并发消息测试
如果并行发送消息，同时有两个消息到服务端，消息内容会混乱吗？客户端进行并行消息发送测试。下面为测试结果，发现并没有问题，说明一个消息可能没有被拆分，或则即使被拆分了在网络通讯底层也会恢复原来的消息结构。
Parallel.For(1, 10, (i) =>
{
var Replaystr =
$"{{Client:1:MessageID:{i};Client发送时间:{DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss:fff")}}}";
var strbytes = Encoding.UTF8.GetBytes(Replaystr);
socket.Send(strbytes, 0, strbytes.Length, SocketFlags.None);
});
Server收到消息:{Client:1:MessageID:2;Client发送时间:2020-04-11 17:11:44:568};Server收到消息的时间:2020-04-11 17:11:44:572
Server收到消息:{Client:1:MessageID:1;Client发送时间:2020-04-11 17:11:44:568};Server收到消息的时间:2020-04-11 17:11:44:575
Server收到消息:{Client:1:MessageID:4;Client发送时间:2020-04-11 17:11:44:572};Server收到消息的时间:2020-04-11 17:11:44:576
Server收到消息:{Client:1:MessageID:5;Client发送时间:2020-04-11 17:11:44:572};Server收到消息的时间:2020-04-11 17:11:44:576
Server收到消息:{Client:1:MessageID:6;Client发送时间:2020-04-11 17:11:44:572};Server收到消息的时间:2020-04-11 17:11:44:576
Server收到消息:{Client:1:MessageID:7;Client发送时间:2020-04-11 17:11:44:572};Server收到消息的时间:2020-04-11 17:11:44:576
Server收到消息:{Client:1:MessageID:8;Client发送时间:2020-04-11 17:11:44:572};Server收到消息的时间:2020-04-11 17:11:44:577
Server收到消息:{Client:1:MessageID:9;Client发送时间:2020-04-11 17:11:44:572};Server收到消息的时间:2020-04-11 17:11:44:577
Server收到消息:{Client:1:MessageID:3;Client发送时间:2020-04-11 17:11:44:571};Server收到消息的时间:2020-04-11 17:11:44:577
并发客户端测试
再进一步测试，假设有多个客户端同时连接，并行发送消息。
Parallel.For(0, 9, (Clienti) =>
{
var socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
var ip = IPAddress.Parse(m_ip);
var endpoint = new IPEndPoint(ip, m_port);
socket.ReceiveTimeout = -1;
Task.Run(() =>
{
socket.Connect(endpoint);
...
...
}
});
结果：这个测试是放在虚拟机中，使用的是NAT网络模式，同一个子网内客户端从发出消息接收服务端返回消息最长耗时有6秒，还是比较夸张的。
服务端结果：
客户端结果：
总结
这个Socket服务在少量客户端连接的时候好像没什么问题，它能抗住大量客户端的连接并发测试吗？我想答案肯定是否定的，为什么呢？因为每个客户端连接都需要消耗1个线程，线程是很昂贵的资源，每个线程自生就要消耗1M内存，100客户端连接什么都不做就消耗了100M，更不用说线程之间的上下文切换需要消耗更宝贵的CPU资源，所以这个服务端根本应对不了大量客户端的连接。
那么最理想的Socket服务端是什么样子的呢？在我看来就是只有与CPU核数相同的线程量在运行，如果4核那么就4个线程在运行，然后每个线程处理超级多的客户端，最好没有阻塞，不休息。怎样才能实现这个目标呢？微软给了一个简单的例子，已经极大程度的实现了这个想法，一起来看看吧
SocketAsyncEventArgs
代码实现
我仿照微软提供的这个实例撸了个简单的Socket服务端
public class SocketArgsServer
{
private static int m_numConnections;
private static int m_receiveBufferSize;
private static int m_sendBufferSize;
private static byte[] m_receivebuffer;
private static Stack<int> m_freeReceiveIndexPool;
private static int m_currentReceiveIndex;
private static byte[] m_sendbuffer;
private static Stack<int> m_freeSendIndexPool;
private static int m_currentSendIndex;
private static Stack<SocketAsyncEventArgs> m_ReadPool;
private static Stack<SocketAsyncEventArgs> m_WritePool;
private static Semaphore m_maxNumberAcceptedClients;
private static int m_numConnectedSockets;
private static int m_totalBytesRead;
private static Socket listenSocket;
public static void Run(string m_ip, int m_port, int numConnections, int m_receiveBuffer, int m_sentBuffer)
{
m_numConnections = numConnections;
m_receiveBufferSize = m_receiveBuffer;
m_sendBufferSize = m_sentBuffer;
m_receivebuffer = new byte[m_receiveBufferSize * m_numConnections];
m_freeReceiveIndexPool = new Stack<int>();
m_currentReceiveIndex = 0;
m_sendbuffer = new byte[m_sendBufferSize * m_numConnections];
m_freeSendIndexPool = new Stack<int>();
m_currentSendIndex = 0;
m_ReadPool = new Stack<SocketAsyncEventArgs>(m_numConnections);
m_WritePool = new Stack<SocketAsyncEventArgs>(m_numConnections);
m_maxNumberAcceptedClients = new Semaphore(m_numConnections, m_numConnections);
m_numConnectedSockets = 0;
m_totalBytesRead = 0;
for (int i = 0; i < m_numConnections; i++)
{
var readEventArg = new SocketAsyncEventArgs();
readEventArg.Completed += new EventHandler<SocketAsyncEventArgs>(ReadWriteIOComleted);
readEventArg.UserToken = new AsyncUserToken();
if (m_freeReceiveIndexPool.Count > 0)
{
readEventArg.SetBuffer(m_receivebuffer, m_freeReceiveIndexPool.Pop(), m_receiveBufferSize);
}
else
{
if ((m_receiveBufferSize * m_numConnections - m_receiveBufferSize) < m_currentReceiveIndex)
{
new ArgumentException("接收缓存设置异常");
}
readEventArg.SetBuffer(m_receivebuffer, m_currentReceiveIndex, m_receiveBufferSize);
m_currentReceiveIndex += m_receiveBufferSize;
}
m_ReadPool.Push(readEventArg);
var writeEventArg = new SocketAsyncEventArgs();
writeEventArg.Completed += new EventHandler<SocketAsyncEventArgs>(ReadWriteIOComleted);
writeEventArg.UserToken = new AsyncUserToken();
if (m_freeSendIndexPool.Count > 0)
{
writeEventArg.SetBuffer(m_sendbuffer, m_freeSendIndexPool.Pop(), m_sendBufferSize);
}
else
{
if ((m_sendBufferSize * m_numConnections - m_sendBufferSize) < m_currentSendIndex)
{
new ArgumentException("发送缓存设置异常");
}
writeEventArg.SetBuffer(m_sendbuffer, m_currentSendIndex, m_sendBufferSize);
m_currentSendIndex += m_sendBufferSize;
}
m_WritePool.Push(writeEventArg);
}
listenSocket = new Socket(new IPEndPoint(IPAddress.Parse(m_ip), m_port).AddressFamily, SocketType.Stream, ProtocolType.Tcp);
listenSocket.Bind(new IPEndPoint(IPAddress.Parse(m_ip), m_port));
listenSocket.Listen(100);
StartAccept(null);
Console.WriteLine("Press any key to terminate the server process....");
Console.ReadKey();
}
public static void ReadWriteIOComleted(object sender, SocketAsyncEventArgs e)
{
switch (e.LastOperation)
{
case SocketAsyncOperation.Receive:
ProcessReceive(e);
break;
case SocketAsyncOperation.Send:
ProcessSend(e);
break;
default:
throw new ArgumentException("The last operation completed on the socket was not a receive or send");
}
}
public static void ProcessSend(SocketAsyncEventArgs e)
{
if (e.SocketError == SocketError.Success)
{
AsyncUserToken token = (AsyncUserToken)e.UserToken;
bool willRaiseEvent = token.Socket.ReceiveAsync(token.readEventArgs);
if (!willRaiseEvent)
{
ProcessReceive(token.readEventArgs);
}
}
else
{
CloseClientSocket(e);
}
}
public static void CloseClientSocket(SocketAsyncEventArgs e)
{
AsyncUserToken token = e.UserToken as AsyncUserToken;
try
{
token.Socket.Shutdown(SocketShutdown.Send);
}
catch (Exception exception)
{
Console.WriteLine(exception);
}
token.Socket.Close();
Interlocked.Decrement(ref m_numConnectedSockets);
m_ReadPool.Push(token.readEventArgs);
m_WritePool.Push(token.writeEventArgs);
token.Socket = null;
token.readEventArgs = null;
token.writeEventArgs = null;
m_maxNumberAcceptedClients.Release();
}
public static void ProcessReceive(SocketAsyncEventArgs e)
{
AsyncUserToken token = (AsyncUserToken)e.UserToken;
if (e.BytesTransferred > 0 && e.SocketError == SocketError.Success)
{
Interlocked.Add(ref m_totalBytesRead, e.BytesTransferred);
byte[] data = new byte[e.BytesTransferred];
Array.Copy(e.Buffer, e.Offset, data, 0, e.BytesTransferred);
var recestr = Encoding.UTF8.GetString(data);
var Replaystr =
$"Server收到消息:{recestr};Server收到消息的时间:{DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss:fff")}";
Console.WriteLine(Replaystr);
var strbytes = Encoding.UTF8.GetBytes(Replaystr);
Array.Copy(strbytes, 0, token.writeEventArgs.Buffer, token.writeEventArgs.Offset,
strbytes.Length);
bool willRaiseEvent = token.Socket.SendAsync(token.writeEventArgs);
if (!willRaiseEvent)
{
ProcessSend(token.writeEventArgs);
}
}
else
{
CloseClientSocket(e);
}
}
public static void ProcessAccept(SocketAsyncEventArgs e)
{
Interlocked.Increment(ref m_numConnectedSockets);
SocketAsyncEventArgs readEventArgs = m_ReadPool.Pop();
SocketAsyncEventArgs writeEventArgs = m_WritePool.Pop();
((AsyncUserToken)readEventArgs.UserToken).Socket = e.AcceptSocket;
((AsyncUserToken)readEventArgs.UserToken).readEventArgs = readEventArgs;
((AsyncUserToken)readEventArgs.UserToken).writeEventArgs = writeEventArgs;
((AsyncUserToken)writeEventArgs.UserToken).Socket = e.AcceptSocket;
((AsyncUserToken)writeEventArgs.UserToken).readEventArgs = readEventArgs;
((AsyncUserToken)writeEventArgs.UserToken).writeEventArgs = writeEventArgs;
bool willRaiseEvent = e.AcceptSocket.ReceiveAsync(readEventArgs);
if (!willRaiseEvent)
{
ProcessReceive(readEventArgs);
}
StartAccept(e);
}
public static void StartAccept(SocketAsyncEventArgs listenEventArg)
{
if (listenEventArg == null)
{
listenEventArg = new SocketAsyncEventArgs();
listenEventArg.Completed += new EventHandler<SocketAsyncEventArgs>((sender, e) => ProcessAccept(e));
}
else
{
listenEventArg.AcceptSocket = null;
}
m_maxNumberAcceptedClients.WaitOne();
bool willRaiseEvent = listenSocket.AcceptAsync(listenEventArg);
if (!willRaiseEvent)
{
ProcessAccept(listenEventArg);
}
}
}
class AsyncUserToken
{
public Socket Socket { get; set; }
public SocketAsyncEventArgs readEventArgs { set; get; }
public SocketAsyncEventArgs writeEventArgs { set; get; }
}
并发测试
先直接上测试结果，该测试环境还是在虚拟机中，忽略一下服务端收到消息时间，因为虚拟机时间和主机时间不是同步的。可以看到服务端发送消息到接收到消息最长耗时2s。
总结
这个Socket服务端直接丢弃了线程的概念，通过SocketAsyncEventArgs来实现了之前线程实现的所有功能。一个SocketAsyncEventArgs来监测连接，客户端连接的时候从SocketAsyncEventArgsPool中分配两个SocketAsyncEventArgs分别负责读写消息。读写消息的缓存块也进行了统一管理，共同组成一个大的缓存块进行重复使用。当客户端失去连接的时候将分配的读写SocketAsyncEventArgs返还给SocketAsyncEventArgsPool进行重复使用。
最后
在本文中探索了两种socket服务端的实现，并对这两种socket服务端进行了简单的剖析，我看了SuperSocket的底层实现思想采用的是第二种方式。目前这种方式的弊端我还没想到，欢迎大家一起探讨。