C / C++ / MFC

Quote:

The problem is, if my server must send data to client, it waits 5 seconds because recv function blocks thread.

Quote:

I try to launch another thread (for each client) for send operation, but cpu works 100%.

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);
                j++;
                strncpy(message, "ACK\n\r",5);
                send(pClientInfo -> hClientSocket , message , 5 , 0);
            }
        }
    }
    return(TRUE);
}

Daniel Pfeffer wrote:

IMO, a multithreaded blocking recv() implementation is conceptually much simpler than a non-blocking recv() implementation.

Daniel Pfeffer wrote:

If you only have one physical machine, I suggest installing Windows in a virtual machine, and running one of the tasks there. That would ensure that the platforms are separate, and would help you to track down the 100% CPU issue.

Albert Holguin wrote:

This might actually yield the same result. The issue is the super low latency in the network when everything is co-located. Essentially if you're tx and rx run as fast as possible, it could take up all the CPU time available

CPallini wrote:

As far as I know, the server's send is not blocked by the client recv.