Yes, I'm testing clients with server on the same machine. My goal is: if the system works fine on my pc, I will have no problems on server machine. Is there a minimal example of recv no blocking?

I post my code:

DWORD WINAPI cliTh1( LPVOID lpData ){
struct CLIENT_INFO *pClientInfo;
char szClientMsg[250];
char packet[50];
HANDLE clientTxThread;

pClientInfo = (struct CLIENT\_INFO \*)lpData ;
char \*ip = inet\_ntoa(pClientInfo->clientAddr.sin\_addr);
printf("SOCKET:%d  - IP:%s  - THREAD\_ID:%ld\\n", pClientInfo->hClientSocket, ip   
                                               ,GetCurrentThreadId());
Q->pClient = pClientInfo;
pClientInfo->primaConn = 0;
pClientInfo->indirizzo = 0;
pClientInfo->p = getDisconnect;
while ( 1 ){
    if(j>=MAXELEMENTS){j=0;};
    if(WSAGetLastError()){
        if(pClientInfo->primaConn == 1){
            disconnectBuffer\[pClientInfo->indirizzo\] = 1;
            pClientInfo->primaConn=0;
        }
        if(disconnectBuffer\[pClientInfo->indirizzo\] == 1){
            creaPackDisc(packet, pClientInfo->indirizzo);
            strcpy(bufferRx\[j\].packet, packet);
            Enqueue(Q,  packet);
            j++;
        }else{
            closesocket(pClientInfo->hClientSocket);
            ExitThread(pClientInfo->txThId);
            ExitThread(GetCurrentThreadId());
        }
        Sleep(1000);
    }else{
        if((pClientInfo->primaConn == 0) && (pClientInfo->indirizzo != 0)){
            pClientInfo->connessione = setConnect(GetCurrentThreadId(), pClientInfo->indirizzo, ip);
            if(pClientInfo->connessione == 1){
                pClientInfo->primaConn = 1;
            }
            //THREAD TX for each client
            clientTxThread = CreateThread(NULL,0,(LPTHREAD\_START\_ROUTINE)txThread, 
                                          pClientInfo,0,&pClientInfo->txThId);
            if ( clientTxThread == NULL ){
                printf("Unable to create client thread");
            } else {
                CloseHandle( clientTxThread ) ;
            }
        }
        if(recv( pClientInfo -> hClientSocket, szClientMsg, sizeof( szClientMsg ), 0  ) > 0){
            strcpy(bufferRx\[j\].packet, szClientMsg);
            memset(&szClientMsg\[0\], 0, sizeof(szClientMsg));
            pClientInfo->indirizzo = calcolaHighLow(bufferRx\[j\].packet\[1\], bufferRx\[j\].packet\[2\],  
                                                   bufferRx\[j\].packet\[3\], bufferRx\[j\].packet\[4\]);
            Enqueue(Q,  bufferRx\[j\].packet);

Thanks for reply. The problem is, if my server must send data to client, it waits 5 seconds because recv function blocks thread. I try to launch another thread (for each client) for send operation, but cpu works 100%.

Hi, I'm developing a server multithread (multiclient) and I have a problem with recv function (c language - SO: windows). My clients send info to server every 5 seconds and recv function blocks thread until info arrives. I try with ioctlsocket, but the number of byte read always is 0; I try with flag MSG_PEEK, but the data is copied into the buffer, but is not removed from the input queue and so I have many messages. Is there a way to perform recv function no blocking? THANKS

Thanks for your advices!!!! I will correct code source.

I find my error!!!! thanks a lot. You advised me to control array size....

Thanks for reply. I declared:

HANDLE hClientThread[65000]
struct CLIENT_INFO clientInfo[10000]

I launch 20 client process.

Hi, I'm developing a client-server C language in Windows. The client connects to server and every 5 seconds send a message. The communication is OK and server receives messages. I try to develop multi-client (.bat file starts client.exe) - server but I have problem: A segmentation fault appears after n messages. This is my code: main

//INIT WINSOCK
if (WSAStartup(MAKEWORD(2,2),&wsa) != 0){
printf("Failed. Error Code : %d",WSAGetLastError());
return 1;
}
//CREATE SOCKET
if((s = socket(AF_INET , SOCK_STREAM , 0 )) == INVALID_SOCKET){
printf("Could not create socket : %d" , WSAGetLastError());
}
//sockaddr_in structure
server.sin_family = AF_INET;
server.sin_addr.s_addr = INADDR_ANY;
server.sin_port = htons( 8888 );
//BIND
if( bind(s ,(struct sockaddr *)&server , sizeof(server)) == SOCKET_ERROR){
printf("Bind failed with error code : %d" , WSAGetLastError());
}
//LISTEN
listen(s , 10000);
//WAIT CONNECTION
puts("Waiting for incoming connections...");
while( TRUE ) {
new_socket = accept(s , (struct sockaddr *)&client, &c);
if (new_socket == INVALID_SOCKET){
printf("accept failed with error code : %d" , WSAGetLastError());
}else{
clientInfo[cont].clientAddr = client ;
clientInfo[cont].hClientSocket = new_socket;
hClientThread[cont] = CreateThread(NULL,0,( LPTHREAD_START_ROUTINE ) cliTh1,( LPVOID ) &clientInfo[cont],0,&dwThreadId ) ;

        if ( hClientThread\[cont\] == NULL ){
            printf("Unable to create client thread");
        } else {
            printf("thread OK\\n");
            CloseHandle( hClientThread\[cont\] ) ;
            cont++;
        }
    }
}

Thread function (cliTh1)

DWORD WINAPI cliTh1( LPVOID lpData ){
struct CLIENT_INFO *pClientInfo;
char szClientMsg[250];
static int j = 0;
int i = 0;
char *message;

pClientInfo = (struct CLIENT\_INFO \*)lpData ;
printf("SOCKET:%d - THREAD\_ID:%ld\\n", pClientInfo->hClientSocket, GetCurrentThreadId());
while ( 1 ){
    if(WSAGetLastError()){
        printf("CURRENT:%ld\\n", GetCurrentThreadId());
        closesocket(pClientInfo->hClientSocket);
        ExitThread(GetCurrentThreadId());
    }
    if(recv( pClientInfo -> hClientSocket, szClientMsg, sizeof( szClientMsg ), 0 ) > 0){
        if(j>5000){j=0;};