Or to put it another way: depending on the timeout value, select() can achieve blocking or non-blocking I/O on several sockets simultaneously. In both cases, th

Or to put it another way: depending on the timeout value, select() can achieve blocking or non-blocking I/O on several sockets simultaneously. In both cases, the sockets themselves can be either blocking or non-blocking. There is no practical difference between blocking on select() for multiple sockets or blocking on recv() for a single socket - in both cases the thread can't do anything else.