Trying to step through BackgroundWorker code in debug but program ends unexpectedly

Question

Here is the code I am working with:

try
{
    mainWorker = new BackgroundWorker();
    mainWorker.DoWork += (sender, e) =>
    {
        try
        {
            //stuff I want to have happen in the background
            ...
            //I want to step through the lines in this try block
        }
        catch
        {
            //exception not being caught
        }
    };
    mainWorker.RunWorkerCompleted += (sender, e) =>
    {
        //code to let user know that the background work is done
         ...
    };
    mainWorker.RunWorkerAsync();
    mainWorker.Dispose();
}
catch
{
    //exception not being caught
}

I do not see any exceptions being thrown. I have a breakpoint set inside the try block in DoWork. Sometimes it hits the breakpoint, but after stepping through a certain number of lines the program ends. It doesn't always end on the same line of code. Sometimes it doesn't hit the breakpoint at all.

The code steps through normally if I eliminate the background worker.

I haven't implemented background workers before and I'm trying to figure out what I'm missing that's preventing me from stepping through my code.

edit: forgot to mention that if I comment out Dispose() it still doesn't step through.

is it console application or winforms? – Dmitrii Dovgopolyi Oct 01 '13 at 22:22 — Dmitrii Dovgopolyi, Oct 01 '13 at 22:22
It's a console application – Krondorian Oct 01 '13 at 22:23 — Krondorian, Oct 01 '13 at 22:23

Dmitrii Dovgopolyi · Accepted Answer · 2013-10-01T22:33:29.793

5

Try adding Console.Readline(); before mainWorker.Dispose();. It is possible that your application stops before BackgroundWorker does its job.

BackgroundWorker is runing as background thread, so it is terminated if main thread stops.

You can test it on simple example. This code will show only one number.

static void Main(string[] args)
{
    BackgroundWorker mainWorker = new BackgroundWorker();
    mainWorker.DoWork += (sender, e) =>
        {
            for (int i = 0; i < 5; i++)
            {
                Console.WriteLine(i);
                Thread.Sleep(500);
            }
        };
    mainWorker.RunWorkerAsync();
}

but if you add stop your main thread by Console.Readline(); you will have all the numbers and can step through DoWork code in debug.

edited Oct 01 '13 at 22:33

answered Oct 01 '13 at 22:25

Dmitrii Dovgopolyi

6,231
2
27
44

after you mentioned this and reviewing your comment in my OP, I thought to confirm the Output type of my project and it wasn't set to console after all. After setting the output type to console, it now steps through properly! – Krondorian Oct 01 '13 at 22:33
So if I tried a backgroundworker in an ASP.NET MVC controller the background thread would be terminated unpredictably, correct ?? – Bill Greer Jul 10 '14 at 20:35

score 2 · Answer 2 · answered Oct 14 '14 at 09:00

I found that in order for exceptions to be thrown so that I can debug through code running in a backgroundworker thread I need to turn on "Enable Just My Code" in Tools => Options => Debugging => General => Enable Just My Code.

Then make sure that in Debug => Exceptions the "Common Language Runtime Exceptions" checkbox is checked for both Thrown and User-unhandled exceptions.

score 0 · Answer 3 · answered Jun 13 '14 at 08:53

0

Also check for exceptions which may exits your main thread.

answered Jun 13 '14 at 08:53

Ruwan Jayalath

361
5
10

Trying to step through BackgroundWorker code in debug but program ends unexpectedly

3 Answers3

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