(PHP 4 >= 4.1.0, PHP 5, PHP 7, PHP 8)

socket_set_nonblockSets nonblocking mode for file descriptor fd


socket_set_nonblock(Socket $socket): bool

The socket_set_nonblock() function sets the O_NONBLOCK flag on the socket specified by the socket parameter.

When an operation (e.g. receive, send, connect, accept, ...) is performed on a non-blocking socket, the script will not pause its execution until it receives a signal or it can perform the operation. Rather, if the operation would result in a block, the called function will fail.



A Socket instance created with socket_create() or socket_accept().

Return Values

Returns true on success or false on failure.


Version Description
8.0.0 socket is a Socket instance now; previously, it was a resource.


Example #1 socket_set_nonblock() example

= socket_create_listen(1223);


This example creates a listening socket on all interfaces on port 1223 and sets the socket to O_NONBLOCK mode. socket_accept() will immediately fail unless there is a pending connection exactly at this moment.

See Also

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User Contributed Notes 1 note

kpobococ at gmail dot com
14 years ago
Beware, when using this function within a loop (i.e. a demon with a socket). The socket_accept(), for example, emits a warning each time there is no incoming connection available to be read. My php error log file got huge in a matter of seconds, eventually crashing the server.

Of course, i used the @ before the function to take care of that problem.

[EDITOR: One can (and should) use socket_select to detect a new connection on a socket (it's a "readable" event)]
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