i am studying c++ server programming but thread is not working - c++

Question

#include "create.h"
std::mutex acceptMutex;
namespace kojang{
CreateServer::CreateServer()
{
init();
}
void CreateServer::showError(const char * msg)
{
std::cout << "에러 : " << msg << std::endl;
exit(-1);
}
void CreateServer::init()
{
WSAStartup(MAKEWORD(2, 2), &wsa);
server = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
if (server == INVALID_SOCKET)
showError("서버 생성 실패");
addr.sin_family = AF_INET;
addr.sin_addr.s_addr = inet_addr("192.168.0.2");
addr.sin_port = htons(23000);
if (bind(server, (sockaddr *)&addr, sizeof(addr)) == SOCKET_ERROR)
showError("바인딩 실패");
if (listen(server, SOMAXCONN) == SOCKET_ERROR)
showError("듣기 실패");
}
void CreateServer::Accept()
{
while (true)
{
std::cout << "클라이언트 접속 대기중.... " << std::endl;
c_size = sizeof(c_addr);
acceptMutex.lock();
client = accept(server, (SOCKADDR*)&c_addr, &c_size);
if (client == INVALID_SOCKET)
{
std::cerr << "error" << std::endl;
acceptMutex.unlock();
continue;
}
v.emplace_back(client);
acceptMutex.unlock();
std::thread t1 = std::thread([this]{ this->run_r(&client);});
t1.detach();
}
}
void CreateServer::run_r(void* client)
{
rcv_msg(client);
}
void CreateServer::rcv_msg(void* data)
{
SOCKET* cl = (SOCKET*)data;
int len;
char message[500];
while ((len = recv(*cl, message, sizeof(message) - 1, 0)) != -1)
{
std::cout << len <<" byte" << std::endl;
std::for_each(v.begin(), v.end(), [&len, &message, &cl](SOCKET sock){ send(sock, message, len, 0); });
}
}
}
thread will be created when client connect server
but if 3 client connnect server ,last client's thread is running well but first,second client's thread did not run;

Answer 1

You're passing a pointer to the same socket (&client) to all the threads, so all threads are using the same one.
You should pass client instead.
std::thread t1 = std::thread([this]{ this->run_r((void*)client);});
// ...
void CreateServer::rcv_msg(void* data)
{
SOCKET cl = (SOCKET)data;
int len;
char message[500];
while ((len = recv(cl, message, sizeof(message) - 1, 0)) != -1)
// ...

Answer 2

void CreateServer::Accept()
{
while (true)
{
std::cout << "클라이언트 접속 대기중.... " << std::endl;
c_size = sizeof(c_addr);
acceptMutex.lock();
SOCKET client = accept(server, (SOCKADDR*)&c_addr, &c_size);
if (client == INVALID_SOCKET)
{
std::cerr << "error" << std::endl;
acceptMutex.unlock();
continue;
}
v.emplace_back(client);
acceptMutex.unlock();
std::thread t1 = std::thread([this,client]{ this->run_r((void*)&client);});
t1.detach();
}
}
i just change my code like this
thank you for everyone
i used same socket in different thread