CODEWITHSUNDEEP
c#winformsmultithreading
Craig Johnston
Craig Johnston

Reputation: 7607

C#: "not responding" window when program is doing some background processing

In my C# project I have a form that is displayed which shows a progress bar.

Some processing is then done which involves communication over the internet.

While this processing is occurring the form says "Not Responding" when run in Win 7, in XP the form just goes white.

Either way, it is not acceptable.

Do I need to use threads to solve this problem?

What are some of the basics of threads that I would need to use in this scenario?

Upvotes: 1

Views: 9084

Answers (7)

Pat Campbell
Pat Campbell

Reputation: 11

A cheaper option is to add the line Application.DoEvents() inside whatever loops your app is running, which will cause it to process messages each time it gets there.

Upvotes: 1

morechilli
morechilli

Reputation: 9817

From your description I'll assume that all your work is currently being done on a single thread, the main thread which is also used for your GUI.

The progress bar can only update when that main thread gets a chance to check its state and apply any expected changes.

Therefore it is important that your processing work does not occupy the main thread for extended periods of time.

There are two main approaches to handling this:

  1. Stepping the processing activity. Break down the processing step into a number of serial tasks - each short in nature. Progressively call each of these serial tasks in the OnIdle event on your main thread.

  2. Using a background thread. See other answers giving more detail on how this would work.

The stepping approach can be useful if you want to avoid the sublties of thread synchronisation. The threading approach is probably better but only essential if it is impossible to guarantee serial short steps.

Upvotes: 0

Sanjeevakumar Hiremath
Sanjeevakumar Hiremath

Reputation: 11263

Yes you have to use threads to keep your UI responsive while something gets done in background. But this question cannot be just answered just like "use Threads to solve it", because there are a lot of forms in which you could use threads. (Backgroundworker, Threadpool, Asynch IO, Creating a Thread, Task Parallel Library, CCR, and a lot more you could imagine for every kind of parallelization scenarios).

As you said you are doing some processing which needs connecting to internet. Where does the most amount of time spent? is it IO over network which takes most time in that case probably Asynchronous IO makes a lot of sense. If time spent is in one huge processing operation then Background worker is perfect, but if this processing can be further broken down into smaller chunks of parallel processing tasks then TPL or ThreadPool is preferred. Till now I am talking only about some processing which happens on Windows forms event, and keep the UI responsive. But based on the scenario there are numerous other options you could use to make threading work for you.

  1. Asynch IO doesnt look like you are doing threading but it more matches with eventing model of winforms. So you could look at that if you are very comfortable with event based programming.
  2. Threadpool looks more like a queue of workers to which you could keep throwing all the work needs to be done, and the framework figures out how many threads to run based on the kind of machine you are using (dual core, quad core etc) and it would get your work items doen in optimal way.

Bottom line its not one answer to use one over other, instead based on the kind of problem you are solving threading model needs to be decided on.

Upvotes: 1

Fun Mun Pieng
Fun Mun Pieng

Reputation: 6891

As long as the program remain in the function to process something, the UI will not update. That is why you may need to start a background thread, so that your UI can continue functioning while your background thread can do the work. An alternatively is to use asynchronous functions.

example of background thread

Upvotes: 0

BitKFu
BitKFu

Reputation: 3697

Your processing must be done within a thread. Out of your thread you have to invoke your progress bar to show the progress.

progressBar1.Invoke((MethodInvoker)delegate
{
progressBar1.Value = (int)((i / limit) * 100);
});

Upvotes: 1

Anuraj
Anuraj

Reputation: 19598

Yes, better way is use BackGroundWorker component. It is wrapper over threads, so you don't need to manage threads. You can get more info from Background worker on MSDN

Upvotes: 0

Fox32
Fox32

Reputation: 13560

If you use System.Net.WebClient, you can use DownloadDataAsync() to communicate in a non blocking way. The System.Net.Sockets.Socket class proviede non blocking communication, too.

Upvotes: 0

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