解决应用程序失去焦点时发生的桌面崩溃

Question

I'm working on a simulation code where I have a "Project" which can hold numerous simulations. You can choose to run them one at a time, or you can run them all in sequence. In this specific case, I have 18 simulations which run one by one, and overall the process takes about 20 sec.

In short, a button is pressed on a form, and the following actions occur:

1) Create simulation object
2) Perform simulation start command
3) Write simulation data to file
4) Dispose simulation object
5) Update DataGridView which holds the simulation list (rewrites "Processing" to "Complete")
6) Update progress bar value in user control.
7) Refresh user control.

Rough source code is as follows:

for (int i = 0; i < dataSet.Count; i++)
{
  using (Processor p = new Processor())
  {
    bool didTestPass = p.RunTest(dataSet[i]);

    if (didTestPass)
      dataGridViewProcessList.Rows[i].Cells[5].Value = "Run complete.";
    else
      dataGridViewProcessList.Rows[i].Cells[5].Value = "Run completed with errors.";
  }

  progressBarRuntime.Value = ((i+1) / dataSet.Count) * 100;

  this.Refresh();
  this.OnUpdateMainForm(this, null);
}

What I've found is, if you remain within the application's focus, all 18 simulations run fine. However, if you drop focus (say, switch to another program), it consistently behaves erratically at the 8th simulation. I say erratically because it acts differently:

When debugging through Visual Studio , the form freezes briefly, then suddenly all remaining simulations are processed and the progress bar snaps to full.

When running as a standalone program , it crashes straight to desktop. No warning, no exception throw, nothing.

I've also found that if I stay focused and let it reach, say, simulation 14, then drop focus from the program, it will immediately exhibit the above behavior.

I'm not particularly familiar with the concept of performing large calculation efforts under the hood while a Windows Form is active. At first I felt like maybe the Form needed to be refreshed (since this is all happening on a UserControl) but I saw no difference when I put in an event to force the Form to Refresh() .

Answer 1

I ended up discovering that the source of my problem was that I was performing work on the interface's main thread, and as a result it was causing my program to hang and crash to desktop.

I created a BackgroundWorker and placed my work code into the DoWork event, then moved the ProgressBar indicator update into the ProgressChanged event.

More details regarding BackgroundWorker and its implementation at MSDN .

In short, the lesson learned for me is that if an activity in a Form is going to take longer than a few seconds, it should be done using a BackgroundWorker to prevent hanging up the interface.