PHP: Detect and show "Server overloaded" message

Question

I have noticed a few websites such as hypem.com show a "You didnt get served" error message when the site is busy rather than just letting people wait, time out or refresh; aggravating what is probably a server load issue.

We are too loaded to process your request. Please click "back" in your browser and try what you were doing again.

How is this achieved before the server becomes overloaded? It sounds like a really neat way to manage user expectation if a site happens to get overloaded whilst also giving the site time to recover.

Answer 1

Another options is this:

$load = sys_getloadavg();
if ($load[0] > 80) {
    header('HTTP/1.1 503 Too busy, try again later');
    die('Server too busy. Please try again later.');
}

I got it from php's site http://php.net/sys_getloadavg, altough I'm not sure what the values represent that the sys_getloadavg returns

Answer 2

You could simply create a 500.html file and have your webserver use that whenever a 50x error is thrown.

I.e. in your apache config:

ErrorDocument 500 /errors/500.html

Or use a php shutdown function to check if the request timeout (which defaults to 30s) has been reached and if so - redirect/render something static (so that rendering the error itself cannot cause problems).

Note that most sites where you'll see a "This site is taking too long to respond" message are effectively generating that message with javascript.