Threading in ASP.NET : quick start

28 03 2008

Threading. God loves it, and so should you.

It’s pretty easy to get started threading in .NET. So why wait?

But why would you want to multithread? There are plenty of different occasions, but essentially when you have some processes that should run asynchronously. This could include an automatic conversion process for some uploaded file – there’s nothing better than throwing it to a thread (or even a Windows Service) to process. That way, the user doesn’t have to wait for conversion to complete before they get back to your site.

Getting going is pretty easy, the complications come when you start looking at threads that use the same data.

Essentially, you start the Thread either as an empty method call, or by passing it some object. You should at least know what a delegates is first (essentially it is a function that can be passed around like a variable).

Now, I prefer the Parameterised (i’m Aussie, so I don’t like using Z where it’s an S 😛 ) option below just because I often want to pass at least something.

C#

using System.Threading;

ParameterizedThreadStart starter = delegate(object prop){SomeObject.SomeMethod(prop)); };
new
Thread(starter).Start(someObject);

One thing you need to remember here though is, if you are calling this in ASP.NET, then it’s the aspnet_wp.exe process that starts the thread, and if this is killed or restarted somehow, then it will kill your thread also.

It could be killed or restarted for the following reasons:

  • change in global.asax file,
  • change in machine.config,
  • change in web.config
  • change of content of /bin folder
  • IIS service is interrupted (incl restart)
  • Server is restarted

One thing you will learn to love: the Thread.Sleep() method and the System.Threading.Timer class…

Enjoy!

Useful Reference: This article gives a great intro into threads.

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