PHP memory leak in client socket (UDP) - php

Question

:)
I am trying to receive data from a c# realtime application in my php server and then move a picture in the browser according to the data.
There is no problem in data send and receive, but the memory usage for chrome is getteng more and more when running the code.
If I close the socket inside the while loop, performance gets very low but mem usage gets normal.So this is about the open socket...
here is the php code :
<?php
//http://www.binarytides.com/udp-socket-programming-in-php/
//Create a UDP socket
if(!($sock = socket_create(AF_INET, SOCK_DGRAM, 0)))
{
die("Couldn't create socket: [$errorcode] $errormsg \n");
}
echo "Socket created \n";
// Bind the source address
if( !socket_bind($sock, "0.0.0.0" , 41181) )
{
die("Could not bind socket : [$errorcode] $errormsg \n");
}
echo "Socket bind OK \n";
//Do some communication, this loop can handle multiple clients
while(1)
{
//echo "Waiting for data ... \n";
$r = socket_recvfrom($sock, $buf, 20, 0, $remote_ip, $remote_port);
?>
<script type="text/javascript">
var data = "<?php echo $buf ?>";
</script>
<?php
}
socket_close($sock);
?>
and here is the c# function (data sender):
public static void SendUDP(string hostNameOrAddress, int destinationPort, string data, int count)
{
//class member : Socket socket = new Socket(AddressFamily.InterNetwork,SocketType.Dgram, ProtocolType.Udp);
//socket is defined as class member and used here
for (int i = 0; i < count; i++)
{
socket.SendTo(buffer, endPoint);
}
}
Thanks ! :)

Answer 1

The technique you're using is called "long polling". It's a funny way to emulate bidirectional communication, especially with old browsers, but has its downsides.
The problem is that, with time, you are sending a huge amount of payload to the browser.
As you're continuously writing to the browser, the page size increases, and, with it, the DOM tree. All of this has to be stored in memory. I'd assume that when you send only a few of the script chunks, the performance is still ok. But thousands and ten thousands of them will of course eat up your memory.
Also, if you're using diagnostic tools, such as the Chrome Developer Tools or Firebug in Firefox, they store a lot of debugging information, which also consume a lot of memory. (Try disabling them.)
If you've written this code just for fun and experimenting, you shouldn't worry about the memory consumption; it's inherent to long polling.
But if you're trying to write a web application with a real bi-directional communication, you should use something like Web Sockets (and maybe a different language than PHP on the server side).

Answer 2

This is not a real answer to my question, but my experience may help someone.
I couldn't do this "long polling" with a PHP server, and it was the fault of PHP, not the browser.
I have developed a good application working this way using a Node.js server.
My C# app is used to process images from a camera. The real-time data resulting the image processing is sent over to the Node.js server and from the server to the browser .
Now I use the web technologies to develop a graphical user interface that was very hard to achieve in .Net, and it has many other benefits...