Is my code a performance killer?


I am showing the value of the timer.php through AJAX in index.php . However I am concern about the performance of this, if it is a server killer if there are 30 people online, and things like this. Do you suggest me some edits?

Thank you.


<script language='JavaScript'> setInterval( 'SANAjax();', 1000 ); $(function() { SANAjax = function(){ $('#dataDisplay').load('timer.php'); } }); </script> <div id="dataDisplay"></div>


function time_difference($endtime){ $days= (date("j",$endtime)-1); $hours =date("G",$endtime); $mins =date("i",$endtime); $secs =date("s",$endtime); $diff="'day': ".$days.",'hour': ".$hours.",'min': ".$mins.",'sec': ".$secs; return $diff; } $future_time = mktime(0, 0, 0, 9, 19, 2011); $now_time = strtotime("+2 hours"); $end_time = $future_time - $now_time; $difference = time_difference($end_time); if ($future_time <= $now_time ) { echo "Date reached"; } else { echo $difference; }; ?>


Depends on your server specs and number of clients, this could quickly become a server-killer.

The multiple calls to a file every second will quickly put a lot of load for nothing though, so best practice calls for using a javascript timer countdown. I particularly like this one: <a href="http://stuntsnippets.com/javascript-countdown/" rel="nofollow">http://stuntsnippets.com/javascript-countdown/</a>

And for the jQuery implementation:

<script type="text/javascript"> var myDate = new Date(); //Retrieve actual date myDate.setTime(this.getTime() + (3600 * 2)); //Add two hours $(document).ready(function() { $("#time").countdown({ date: myDate.toGMTString(), onComplete: function( event ){ $(this).html("completed"); }, leadingZero: true }); }); </script> <p id="time" class="time">

This should be enough, no more need for PHP calls and the client does everything.


By setting a setInterval for every second, you are basically saying that for 30 clients, you will be getting roughly 30 txn per second to your php server. Its hard to say its a performance killer outside of just saying you will have to handle 30tps for this simple call. I would first quesiton why you are doing this with a server side script. You could just as easily give the html file a datetime when the page loads and do the countdown with just javascript in the browser.


I use jQuery Countdown <a href="http://keith-wood.name/countdown.html" rel="nofollow">http://keith-wood.name/countdown.html</a> to put a timer on my pages to let the user know when they are going to be logged out of the system due to inactivity.

You can bind a function to the counter expiring event.

<a href="http://code.google.com/p/jquery-countdown/" rel="nofollow">http://code.google.com/p/jquery-countdown/</a> ...Simple example

<a href="http://keith-wood.name/countdown.html" rel="nofollow">http://keith-wood.name/countdown.html</a> ...shows off all the bells and whistles...

It can be as simple as the first one or as detailed as the second!



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