Calling Thread.Run in an ASP.Net application running on IIS

Question

Consider the following code which runs in an ASP.Net web application on IIS...

_thread = new Thread(Method1)
_thread.Start();

As there is a thread pool within the ASP.Net process what is the effect of this code? Specifically...

Will it take another thread from the ASP.Net thread pool? Or from a different threadpool? Or does this code bypass the thread pool and just get a new thread?
Is this the same thread pool that is used to serve page requests? Therefore, this code which was put in to improve performance could actually reduce it by taking another thread that could be used to serve another resource to another user?
Is the thread pool only used for serving non-static resources? Does IIS have it's own thread pool for serving resources that do not run through the managed pipeline?
What would happen if the App. Pool was recycled after calling _thread.Start()? Would IIS allow this thread to complete before closing down the application pool?
It seems to be that this code forces the creation of a new thread. Would there be a benefit to swapping this code to use Async/Wait? The code that runs in Method1() is IO bound.

You should not create new threads yourself in ASP.NET. See Scott Hanselman's excellent blog post. — mason
– mason, Commented Feb 13, 2016 at 2:01

Lex Li · Accepted Answer · 2016-02-12 11:29:18Z

3

When you call new Thread explicitly, that thread is not part of the thread pool. You are fully on your own.
The so called ASP.NET thread pool is purely used to process request messages (to host HttpApplication derived objects).
Static files are served by IIS natively, so the ASP.NET thread pool is for ASP.NET contents only. But here you should notice all happens inside the worker process (w3wp.exe). Just some are processed by native components, while others are by managed components. The pipeline is unified if you are using the integrated pipeline mode.
Application pool recycle only waits for requests to be processed. Your own threads will be killed when all requests are done.
Async/await does not create threads automatically. But by switching to async/await, you do avoid create a thread, and that should help improve performance.

answered Feb 12, 2016 at 11:29

Lex Li

64k12 gold badges126 silver badges163 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Remotec Over a year ago

4. Does this also apply to threads obtained via the Thread Pool?

Lex Li Over a year ago

@RemotecUk fully depends on if a request is being processed by that thread in the pool. If not, then the thread is killed.

Paulo Morgado · Accepted Answer · 2016-02-13 01:46:28Z

0

ASP.NET 4.5+ (the one where you can use async-await) uses the same thread pool to handle requests and to schedule task execution through Task.Run.

When you use Task.Run when handling an ASP.NET request, you'll be changing context to a new thread pool thread and returning the current thread pool thread back to the thread pool. When the task completes, you'll be switching back another thread pool thread.

Using Task.Run when handling an ASP.NET request requires, at least, one more thread pool thread and incurs in, at least two context switches.

The bottom line is that it requires more resources and takes more time to handle the request.

answered Feb 13, 2016 at 1:46

Paulo Morgado

15k3 gold badges36 silver badges64 bronze badges

Collectives™ on Stack Overflow

Calling Thread.Run in an ASP.Net application running on IIS

2 Answers 2

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related