c++ - UDP server consumes all processor time in multithreaded program -


i'm developing client/server application. client , server run on 2 different machines running ubuntu 16.04. client sends 2 variables influence flow of server part, therefore, want decrease packet loss rate as possible. application thread-based.

in 1 thread udp server running. project has gui implemented using qt. when tried implement udp server blocking, whole program , gui froze until packet received. , when packet received program didn't response.

therefore, thought non-blocking udp best way it. managed make udp non-blocking using select(). comes problem. if set timeout of recvfrom 10ms , thread allowed run every 10ms, no packet lost but, apparently, udp thread consumes processor time program freezes. if increased interval of calling thread or reduced timeout interval, around 80% of packets lost. know udp connectionless protocol , tcp may better option, have use udp client side sends packets on udp.

the question is: how can reduce packet loss rate without blocking other threads executing efficiently?

following code (the based on stackoverflow answer which, @ moment, can't find refer here).

void receiveudp(void) {     fd_set readfds;     static int fd;     static struct timeval tv;     tv.tv_sec = 0;     tv.tv_usec = 10000;     static char buffer[10];     static int length;      if ( (fd = socket(af_inet, sock_dgram, 0)) < 0 ) {         perror("socket failed");         return;     }      struct sockaddr_in serveraddr;     memset( &serveraddr, 0, sizeof(serveraddr) );     serveraddr.sin_family = af_inet;     serveraddr.sin_port = htons( 50037 );         serveraddr.sin_addr.s_addr = htonl( inaddr_any );          if( bind(fd, (struct sockaddr *)&serveraddr, sizeof(serveraddr)) < 0)     {         perror("bind failed");         return;     }      fcntl(fd, f_setfl, o_nonblock);      fd_zero(&readfds);     fd_set(fd, &readfds);      int rv = select(fd+1, &readfds, null, null, &tv);      if(rv == -1)     {         printf("error in select\n");         _exit(0);     }     else if(rv == 0)     {         printf("timeout\n");     }     else     {         if(fd_isset(fd, &readfds))         {             length = recvfrom(fd, buffer, sizeof(buffer) - 1, 0, null, 0);              if(length < 0)             {                 perror("recvfrom failed");             }             else             {                 printf("%d bytes received: \n", length);             }         }     }      close(fd); }


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