Editing Berkeley sockets (section)

==Blocking and non-blocking mode==
Berkeley sockets can operate in one of two modes: [[blocking (computing)|blocking]] or non-blocking.

A blocking socket does not return control until it has sent (or received) some or all data specified for the operation. It is normal for a blocking socket not to send all data. The application must check the return value to determine how many bytes have been sent or received and it must resend any data not already processed.<ref>{{cite web|url=http://beej.us/guide/bgnet/ |title=Beej's Guide to Network Programming |publisher=Beej.us |date=2007-05-05 |access-date=2012-07-26}}</ref> When using blocking sockets, special consideration should be given to accept() as it may still block after indicating readability if a client disconnects during the connection phase.

A non-blocking socket returns whatever is in the receive buffer and immediately continues. If not written correctly, programs using non-blocking sockets are particularly susceptible to [[race condition]]s due to variances in network link speed.{{citation needed|date=May 2021}}

A socket is typically set to blocking or non-blocking mode using the functions [[fcntl]] and [[ioctl]].