Winsock local client-server benchmarking - c++

Question

I am tying to evaluate the performance of this simple client-server program setting it up in a way where a test client makes a fixed number of requests, say; 10000 and then see how long it takes the server to deal with these and then trying it with multiple clients in parallel since it runs with threads. Now I am wondering how to program this? (sorry just started with Winsock). I was also wondering if this is a proper implementation of threading and if not what could be improved and why. Thanks in advance
Test server code;
Server:
#define _WINSOCK_DEPRECATED_NO_WARNINGS
#pragma comment(lib,"ws2_32.lib") //header file
#include <WinSock2.h>
#include <string>
#include <iostream>
#include <iomanip>
using namespace std;
SOCKET Connections[100];
int ConnectionCounter = 0;
void ClientHandlerThread(int index) //index = the index in the SOCKET Connections array
{
char buffer[256]; //Buffer to receive and send out messages from/to the clients
while (true)
{
recv(Connections[index], buffer, sizeof(buffer), NULL); //get message from client
for (int i = 0; i < ConnectionCounter; i++) //For each client connection
{
if (i == index) //Don't send the chat message to the same user who sent it
continue; //Skip user
send(Connections[i], buffer, sizeof(buffer), NULL);//send the chat message to this client
}
}
}
int main()
{
std::cout << "\n\n\n\n\n Server sucessfully turned on, awaiting for clients...\n\n\n\n\n";
//Winsock Startup
WSAData wsaData;
WORD DllVersion = MAKEWORD(2, 1);
if (WSAStartup(DllVersion, &wsaData) != 0) //initialise winsock library, if WSAStartup returns anything other than 0, then that means an error has occured in the WinSock Startup.
{
MessageBoxA(NULL, "WinSock startup failed", "Error", MB_OK | MB_ICONERROR);
return 0;
}
SOCKADDR_IN addr; //Address that we will bind our listening socket to
int addrlen = sizeof(addr); //length of the address (required for accept call)
addr.sin_addr.s_addr = inet_addr("127.0.0.1"); //Broadcast locally, using inet_address funtion that converts to correct long format.
addr.sin_port = htons(1111); //Port
addr.sin_family = AF_INET; //IPv4 Socket
SOCKET sListen = socket(AF_INET, SOCK_STREAM, NULL); //Create socket to listen for new connections
bind(sListen, (SOCKADDR*)&addr, sizeof(addr)); //Bind the address to the socket
listen(sListen, SOMAXCONN); //Places sListen socket in a state in which it is listening for an incoming connection. Note:SOMAXCONN = Socket Oustanding Max Connections
SOCKET newConnection; //Socket to hold the client's connection
int ConnectionCounter = 0; //# of client connections
for (int i = 0; i < 100; i++)
{
newConnection = accept(sListen, (SOCKADDR*)&addr, &addrlen); //Accept a new connection
if (newConnection == 0) //If accepting the client connection failed
{
std::cout << "Failed to accept the client's connection." << std::endl;
}
else //If client connection properly accepted
{
std::cout << "\n\n\nClient Connected!\n\n" << std::endl;
/* char MOTD[256] = "Welcome! This is the Message of the Day."; //Create buffer with message of the day
send(newConnection, MOTD, sizeof(MOTD), NULL); //Send MOTD buffer */
Connections[i] = newConnection; //Set socket in array to be the newest connection before creating the thread to handle this client's socket.
ConnectionCounter += 1; //Incremenent total # of clients that have connected
cout << "\nConnected Clients: ";
cout << ConnectionCounter;
CreateThread(NULL, NULL, (LPTHREAD_START_ROUTINE)ClientHandlerThread, (LPVOID)(i), NULL, NULL); //Create Thread to handle this client. The index in the socket array for this thread is the value (i).
}
}
system("pause");
return 0;
}
Client:
#define _WINSOCK_DEPRECATED_NO_WARNINGS
#pragma comment(lib,"ws2_32.lib") //Required for WinSock
#include <WinSock2.h> //For win sockets
#include <string> //For std::string
#include <iostream> //For std::cout, std::endl, std::cin.getline
SOCKET Connection;//This client's connection to the server
void ClientThread()
{
char buffer[256]; //Create buffer to hold messages up to 256 characters
while (true)
{
recv(Connection, buffer, sizeof(buffer), NULL); //receive buffer
std::cout << buffer << std::endl; //print out buffer
}
}
int main()
{
//Winsock Startup
WSAData wsaData;
WORD DllVersion = MAKEWORD(2, 1);
if (WSAStartup(DllVersion, &wsaData) != 0)
{
MessageBoxA(NULL, "Winsock startup failed", "Error", MB_OK | MB_ICONERROR);
return 0;
}
SOCKADDR_IN addr; //Address to be binded to our Connection socket
int sizeofaddr = sizeof(addr); //Need sizeofaddr for the connect function
addr.sin_addr.s_addr = inet_addr("127.0.0.1"); //Address = localhost (this pc)
addr.sin_port = htons(1111); //Port = 1111
addr.sin_family = AF_INET; //IPv4 Socket
Connection = socket(AF_INET, SOCK_STREAM, NULL); //Set Connection socket
if (connect(Connection, (SOCKADDR*)&addr, sizeofaddr) != 0) //If we are unable to connect...
{
MessageBoxA(NULL, "Failed to Connect", "Error", MB_OK | MB_ICONERROR);
return 0; //Failed to Connect
}
std::cout << "Connected!" << std::endl;
CreateThread(NULL, NULL, (LPTHREAD_START_ROUTINE)ClientThread, NULL, NULL, NULL); //Create the client thread that will receive any data that the server sends.
char buffer[256]; //256 char buffer to send message
while (true)
{
std::cin.getline(buffer, sizeof(buffer)); //Get line if user presses enter and fill the buffer
send(Connection, buffer, sizeof(buffer), NULL); //Send buffer
Sleep(10);
}
return 0;
}

Answer 1

As #JerryCoffin said, using thread-per-client model burden the server by too many context switches between threads. Modern servers like Nginx web server use an asynchronous non-blocking model to reach scalability. I have developed such an architecture recently. To get more familiar with this model, I provide some useful links for you.
Start with the following to get more familiar with the concept:
Inside NGINX: How We Designed for Performance & Scale
You need to know re-actor and pro-actor design patterns. You can implement them using select() or similar facilities.
Example: Nonblocking I/O and select()
There are also some nice implementations of them in libraries like boost, POCO, and ACE. Personally, I recommend you take a look at the boost asio library. You can find full documentation, tutorial, and examples here.
Boost.Asio