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ViewsUDP network stuck while system waiting/receiving data
I have to build up a bilateral UDP network system, that means both server and client send and receive data, as illustrated by the below diagram:
I took a ready to use example from http://www.binarytides.com/udp-socket-programming-in-winsock/
However, on the client, when a data(string) is sent, the client gets stuck waiting for incoming data on this line:
recvfrom(s, buf, BUFLEN, 0, (struct sockaddr *) &si_other, &slen)
The client cannot send more data until it receives incoming data.
Is there any method that I can keep sending data to the server, while also waiting for incoming data?
1 answers
Answer question0
This is because by default sockets are blocking, which means recv and read family calls will hang until there is data available. You need to either use nonblocking I/O with multiplexing like select() or poll(), or use a separate, dedicated thread for receiving data.
Nonblocking I/O is significantly different in design from blocking I/O code, so there's not a simple change you can make. I recommend you read something like Beej's Guide to Network Programming which covers all of these issues.