WSAWaitForMultipleEvents timeout 佔用 CPU ?

Question

各位大大好，
我的WSAWaitForMultipleEvents當WSA_WAIT_TIMEOUT時會佔用CPU?
要如何解 ?
謝謝各位!

Answer 1

什么叫当WSA_WAIT_TIMEOUT时会占用cpu
WSA_WAIT_TIMEOUT不是返回值么
既然函数返回就是释放所属线程了
占用cpu不是正常的么

Answer 2

我的Socket程序是client端non-blocking程序，以Windows Service执行。以多个thread建立与Server联机，各自有自已的socket id ，各自建立WSAEventSelect，对server端发出电文，等待server端10秒内回应。
正常情况下都没有问题，但当server端没有响应后，于WSAWaitForMultipleEvents回应WSA_WAIT_TIMEOUT时，只show出我的最后一次debug讯息，也没有return，CPU即开始上升至90%，该thread就hand住了,,,int SOCKETServer::Receive(char *recv_msg, int time_out)
{
   DWORD           dwIndex;
   int             bytesRcvd=0, maxDescriptor=0;
   char            msg[40];
   
   memset(msg, 0, 40);
   
   EventTotal = 0;   try {
      hEvent = WSACreateEvent();
   } catch (...) {
      debuglog(ERR, "Socket WSACreateEvent failed");
      ShowWSALastError();
      return FAIL;
   }   if ( hEvent == WSA_INVALID_EVENT ) {
      debuglog(ERR, "Socket WSACreateEvent error");
      ShowWSALastError();
      return FAIL;
   } 
   // WSAEventSelect
   try {
      rv = WSAEventSelect(clntSock, hEvent, FD_READ);
   } catch (...) {
      WSAResetEvent(hEvent);
      WSACloseEvent(hEvent);
      debuglog(ERR, "Socket WSAEventSelect failed");
      ShowWSALastError();
      return FAIL;
   }   if ( rv == SOCKET_ERROR ) {
      WSAResetEvent(hEvent);
      WSACloseEvent(hEvent);
      debuglog(ERR, "Socket WSAEventSelect error");
      ShowWSALastError();
      return FAIL;
   }   SocketArray[EventTotal] = clntSock;
   EventArray[EventTotal]  = hEvent;
   EventTotal++;
   WSANETWORKEVENTS NetworkEvent;
   
   
   try {
      dwIndex = WSAWaitForMultipleEvents(EventTotal, EventArray, FALSE, (time_out*1000), FALSE);
   } catch (...) {
      debuglog(ERR, "Socket WSAWaitForMultipleEvents failed");
      ShowWSALastError();
      WSAResetEvent(hEvent);
      WSACloseEvent(hEvent);
      return FAIL;
   }   if ( dwIndex == WSA_WAIT_FAILED ) {
      debuglog(ERR, "Socket WSAWaitForMultipleEvents error");
      ShowWSALastError();
      WSACloseEvent(hEvent);
      return FAIL;   } else if ( dwIndex == WSA_WAIT_TIMEOUT ) {
      debuglog(ERR, "WSAWaitForMultipleEvents timeout !");
      WSAResetEvent(hEvent);
      WSACloseEvent(hEvent);
      Disconnect();
      ShowWSALastError();   <<<--- 执行到这
      return TIME_OUT;      <<<--- 看起来没有return，因为return后的debug讯息没有show出来   } else if ( dwIndex == WAIT_IO_COMPLETION ) {
      debuglog(ERR, "WSAWaitForMultipleEvents WAIT_IO_COMPLETION !");   } else {
      // do nothing
   }
   try {
      rv = WSAEnumNetworkEvents(SocketArray[dwIndex - WSA_WAIT_EVENT_0], EventArray[dwIndex - WSA_WAIT_EVENT_0], &NetworkEvent);
   } catch (...) {
      debuglog(ERR, "Socket WSAEnumNetworkEvents failed");
      ShowWSALastError();
      WSAResetEvent(hEvent);
      WSACloseEvent(hEvent);
      return FAIL;
   }   if ( rv == SOCKET_ERROR ) {
      debuglog(ERR, "WSAEnumNetworkEvents error !");
      ShowWSALastError();
      WSAResetEvent(hEvent);
      WSACloseEvent(hEvent);
      return FAIL;
   }
   if ( NetworkEvent.lNetworkEvents & FD_READ ) {          try {
             bytesRcvd = recv(SocketArray[dwIndex - WSA_WAIT_EVENT_0], recv_msg, RCVBUFSIZE, 0);
             if ( bytesRcvd == 0 ) {
                debuglog(ERR, "Socket connection has been gracefully closed");
                ShowWSALastError();
                WSAResetEvent(hEvent);
                WSACloseEvent(hEvent);
                return FAIL;             } else if ( bytesRcvd == SOCKET_ERROR ) {
                debuglog(ERR, "socket receive error");
                ShowWSALastError();
                WSAResetEvent(hEvent);
                WSACloseEvent(hEvent);
                return FAIL;             } else if ( bytesRcvd < 0 ) {
                debuglog(ERR, "socket receive error ( bytesRcvd<0 )");
                ShowWSALastError();
                WSAResetEvent(hEvent);
                WSACloseEvent(hEvent);
                return FAIL;             } else {
                // data normally receive
             }
          } catch (...) {
             debuglog(ERR, "Socket receive failed");
             ShowWSALastError();
             WSAResetEvent(hEvent);
             WSACloseEvent(hEvent);
             return FAIL;
          }   }   //sprintf(msg, "socket receive %d bytes", totalBytesRcvd);
   //debuglog(ERROR, msg);   //sprintf(msg, "%s recv", CURRENT_TIME_HHMMSSsss);   //debugdump(bytesRcvd, (unsigned char *)recv_msg, msg);
   WSAResetEvent(hEvent);
   WSACloseEvent(hEvent);   return bytesRcvd;
}谢谢您 !! ^^

Answer 3

WSA_WAIT_TIMEOUT时，WSAWaitForMultipleEvents调用已经返回了，此时占CＰＵ，说明是你的代码占ＣＰＵ，因为现在正在运行你的代码。