Run method asynchronously in asp.net

问题:

I have a webpage with a button that generates some files to a server path. (It takes somewhere from 5 to 20 minutes). I want to create an async task that will continue executing even after the user closes the browser. Is it possible to do this with asp.net 4 and C#?

回答1:

You do not control the thread pool in an asp.net application. You cannot even guarantee that a request will be completed on the same thread that it started with. Creating threads uses the same application pool that the web server uses, and you can use up all the request threads leaving your web server unavailable to process requests.

You should implement a windows service that hosts a WCF service that you can call from within your web application. In the service you can then fire off a thread to process the long running process. At the end of that process you can then update a status flag (e.g from Processing to Complete) that the user can view to determine if the files are done processing.

I would recommend using Topshelf to implement your windows service, it will save you much headache.

回答2:

Actually, it is recommended that you not do this. Instead, the recommended way is to create a service (e.g. a windows service) that performs your processing asynchronously. In your web application, you create methods that starts the process, and another method that polls the service to determine if processing has completed.

There are a number of reasons for this, but one of the biggest is that the default and recommended configuration for webservers allows the server to kill long-running requests.

回答3:

Or that I didn't understand what you want to do, or that you don't need to do a thing.

After the request was sent, the request process continues no matter if the user browser was closed or not. You don't need to do a thing

Fabulous nature of stateless WEB applications...

回答4:

Creating new thread / using thread pool is the easiest approach to create run away tasks.

Note that there is no guarantees that process will stay alive for duration of a long task - so be prepared to handle partial completion and manual restarts. I.e. AppPoll recycle due to config change.

回答5:

Easiest way is to put your task on the ThreadPool. The thread pool threads will stay alive even after the web page has completed rendering. The code would look like the following:

/* Beginning Method */
object someData = new object();
ThreadPool.QueueUserWorkItem(new WaitCallback(ProcessAsync), someData);
/* Ending Method */

static void ProcessAsync(Object stateInfo) 
{
    string dataToString = stateInfo.ToString();
}

回答6:

you have to create a thread that does the long running task

have a look at the below:

http://kiranpatils.wordpress.com/2010/01/01/performing-a-long-running-task-with-asp-net/

Anyway what ever you start on the server it will continue running even if the user close the browser(until you recycle the app-pool or restart the web server).