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As part of a recent project for a client, one of the requirements was to create a script that would run ALL day long, and listen for real-time incoming data through a socket connection.

The script itself was a pain for me to write since I wasn't very experienced in working sockets in PHP to begin with.

I finally got everything working and the script was working like a charm but when I would run the script, the CPU usage on the server would jump up to 100%.

After some hair pulling and research (Google), I came across a great tip. While you're listening for data in your socket connection loop, have it sleep after every iteration through the loop in order to let the CPU "rest".

Here's a stripped down version of my code:

$connection = fsockopen($ip, $port, $errno, $errstr, 30);

stream_set_blocking($connection, false);
stream_set_timeout($connection,65);
$info = stream_get_meta_data($connection);

while($connection && !$info['timed_out'] && !feof($connection)) {
	$data = fgets($connection);
	
	// Do whatever you need to do with the $data
	
	usleep(500);
}

Notice the call to usleep(500) in the code. This solved my CPU usage problem and only halts the script for 500 micro seconds (A micro second is one millionth of a second).

On average the script now only consumes about 1-2% CPU usage throughout the day. Hope this helps someone in the same situation.

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