Blocking vs. Non-blocking Mode
Berkeley sockets can operate in one of two modes: blocking or non-blocking.
A blocking socket will 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. It also may cause problems if a socket continues to listen: a program may hang as the socket waits for data that may never arrive. 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.
On the other hand, a non-blocking socket will return whatever is in the receive buffer and immediately continue. If not written correctly, programs using non-blocking sockets are particularly susceptible to race conditions due to variances in network link speed.
A socket is typically set to blocking or nonblocking mode using the fcntl or ioctl functions.
Read more about this topic: Berkeley Sockets
Famous quotes containing the words blocking and/or mode:
“Cassoulet, that best of bean feasts, is everyday fare for a peasant but ambrosia for a gastronome, though its ideal consumer is a 300-pound blocking back who has been splitting firewood nonstop for the last twelve hours on a subzero day in Manitoba.”
—Julia Child (b. 1912)
“I cannot believe that our factory system is the best mode by which men may get clothing. The condition of the operatives is becoming every day more like that of the English; and it cannot be wondered at, since, as far as I have heard or observed, the principal object is, not that mankind may be well and honestly clad, but, unquestionably, that the corporations may be enriched.”
—Henry David Thoreau (1817–1862)