TCP-сервер устанавливает время ожидания для каждого клиента

Я работаю с этим кодом:

int main(int argc , char *argv[]) {
int device, step=0;
bool writeFuse = false;

int max_clients=CLIENTS;
int opt=TRUE;
int master_socket, activity, new_socket, valread, max_sd;

struct timeval timeout;
timeout.tv_sec = 3;
timeout.tv_usec = 0;

//set of socket descriptors
fd_set readfds;

//initialise all client_socket[] to 0 so not checked
for(int i=0; i<max_clients; i++) {
client_socket[i] = 0;
}

//create a master socket
if((master_socket = socket(AF_INET, SOCK_STREAM, 0)) == 0) {
perror("ERROR - Socket creation failed");
exit(EXIT_FAILURE);
}
else cout << "OK - Socket created." << endl;

//set master socket to allow multiple connections , this is just a good habit, it will work without this
if(setsockopt(master_socket, SOL_SOCKET, SO_REUSEADDR, (char *)&opt, sizeof(opt)) < 0 ) {
perror("ERROR - Socket initialization failed");
exit(EXIT_FAILURE);
}
else cout << "OK - Socket initializated." << endl;

//type of socket created
address.sin_family = AF_INET;
address.sin_addr.s_addr = INADDR_ANY;
address.sin_port = htons( PORT );

//bind the socket to localhost port
if(bind(master_socket, (struct sockaddr *)&address, sizeof(address))<0) {
perror("ERROR - Bind failed");
exit(EXIT_FAILURE);
}
else cout << "OK - Bind successful." << endl;

cout << "Listening on port " << PORT << ":" << endl << endl;

//try to specify maximum of 3 pending connections for the master socket
if(listen(master_socket, 3) < 0) {
perror("listen");
exit(EXIT_FAILURE);
}

//accept the incoming connection
addrlen = sizeof(address);

while (TRUE) {
//clear the socket set
FD_ZERO(&readfds);

//add master socket to set
FD_SET(master_socket, &readfds);
max_sd = master_socket;

//add child sockets to set
for(int i=0; i<max_clients ; i++) {
//socket descriptor
int sd = client_socket[i];

//if valid socket descriptor then add to read list
if(sd > 0)
FD_SET( sd , &readfds);

//highest file descriptor number, need it for the select function
if(sd > max_sd)
max_sd = sd;
}

//wait for an activity on one of the sockets , timeout is NULL , so wait indefinitely
activity = select(max_sd + 1, &readfds, NULL, NULL, NULL);

if((activity < 0) && (errno!=EINTR))
cout << "ERROR - Selection error." << endl;

//if something happened on the master socket , then its an incoming connection
if(FD_ISSET(master_socket, &readfds)) {
if((new_socket = accept(master_socket, (struct sockaddr *)&address, (socklen_t*)&addrlen))<0) {
perror("accept");
exit(EXIT_FAILURE);
}

//inform user of socket number - used in send and receive commands
cout << "New connection accepted. Socket fd: " << new_socket << ", ip: " << inet_ntoa(address.sin_addr) << ", port: " << ntohs(address.sin_port) << "." << endl;

//add new socket to array of sockets
for(int i = 0; i<max_clients; i++) {
//if position is empty
if(client_socket[i] == 0) {
client_socket[i] = new_socket;
cout << "Adding to list of sockets as " << i << "." << endl;
client_status[i] = false;

int sum=0;
for(int j=0; j<CLIENTS; j++)
sum += client_socket[j];
if(sum == new_socket)
message_done(i);

break;
}
}
}

//else its some IO operation on some other socket :)
for(int i=0; i<max_clients; i++) {
int sd = client_socket[i];

if(FD_ISSET(sd, &readfds)) {
//check if it was for closing, and also read the incoming message
if((valread = read(sd, buffer, 1024)) == 0) {
//somebody disconnected, process it
disconnection(sd, i);
}

//everything is ok, can process data
else {
//set the string terminating NULL byte on the end of the data read
if(buffer[valread] != '\0')
buffer[valread] = '\0';
int data = atoi(buffer);
cout << "Client " << i << " send message: " << data << endl;

//some data processing stuff
}
}
}
}

return 0;
}

Это простой TCP-сервер с несколькими подключениями. Я пытаюсь установить время ожидания для каждого из подключенных клиентов. Я искал через Интернет и сделал несколько попыток. Но без успеха.