Cameron Albert

Ramblings of software development, games and technology.

ASP.NET AJAX Server Controls and PBBGs

I ran into a major performance issue with the ASP.NET AJAX Server Controls while testing my persistent browser based game Perenthia. I had initially used update panels fro the various regions on the main game interface such as the player stats, map and chat window. Programming this was simple as I could do everything in the server side code and just send back the results. With the partial page rendering feature of the ASP.NET AJAX Extensions only the update panel html was sent back to the browser.

Once I moved the application into a production environment and had people on there playing and testing the web starting running out of memory, the application was consuming the server memory at an alarming rate. What was happening was that IIS would jump 1 to 2 MB of RAM for each request made by the client, that means every time someone moved on the game map 1 to 2 MB of RAM were being held and not released. I tried a bunch of different stuff from optimizing stored procedures to caching the map data but none of it helped.

I used Firebug to watch the AJAX request and response and to see if I could reduce that down some. The response was simply HTML fragments so I wasn’t too worried about that but the request sent the entire ViewState up to the server with each post. The ViewState for the game page could be quite large since I was appending messages to the chat window which was a server control.

I was able to eliminate the ViewState issue with the chat window but the app was still consuming RAM and not releasing it.

I decided to try just a simple JavaScript only AJAX post using the Microsoft AJAX Client Libraries. After doing some basic tests on the chat window I decided to rebuild the game interface using only client side AJAX calls, no update panels. This has resolved the server memory issue, why, I am still not sure, must be something with the way the resources are handled in .NET. I have not encountered the slow downs or crashes from before and the app is actually running a little smoother on the front end as well.

What I settled on was a custom ASHX handler class that handles the commands from the client and returns JSON strings that the UI can then translate and use to update the interface components. I had to rebuild some of the interface components as JavaScript objects but overall it was the right choice. Not too mention that I can now use that same handler with other interfaces such as Flash or Silverlight.

In conclusion, while the AJAX Server Controls might work great for most web sites they are definitely not optimal for a persistent browser based game (PPBG).

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Written by Cameron

October 1, 2007 at 5:31 pm

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