what causes RunWorkerCompleted to be called?

Question

dI have a winforms system tray application, that is monitoring job status via a database. I click on the system tray, and a menu of currently active jobs opens, and if I click on a job, I create a form which is supposed to show messages and a progress bar.

The form's constructor is

    public JobStatusForm()
    {
        InitializeComponent();

        activeJobsBGWorker = new BackgroundWorker();
        activeJobsBGWorker.DoWork += new DoWorkEventHandler(activeJobsBGWorker_DoWork);
        activeJobsBGWorker.ProgressChanged += new ProgressChangedEventHandler(activeJobsBGWorker_ProgressChanged);
        activeJobsBGWorker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(activeJobsBGWorker_RunWorkerCompleted);
    }

Then, the click event handler for the context method calls JobStatusForm.Show(). In the form, I have:

    private void JobStatusForm_Shown(object sender, EventArgs e)
    {
        activeJobsBGWorker.RunWorkerAsync();
    }

To start the worker.

I find that the worker starts, and then something raises the RunWorkerCompleted event. The sender is a background worker, and the event args are null.

How can I find out what is raising this event , and how can I make it stop/restart?

Thanks,

EDIT:

currently, the Do_Work code looks like this:

private void activeJobsBGWorker_DoWork(object sender, DoWorkEventArgs e)
    {

        //while (!e.Cancel)
        while (true)
        {
            _clr.JobStatus status = _clr.SystemDataHelper.GetCurrentJobActivity(_clr.SystemDataHelper.GetLocation(), this.job_ID);

            //if (activeJobsBGWorker.CancellationPending)
            //    continue;

            activeJobsBGWorker.ReportProgress(status.pc, status);

            Thread.Sleep(250);
        }
    }

I have set a breakpoint on the ReportProgress line, and it is never hit.

The call into _clr is to a C++ project built as a dll, and calls a static method which calls the database.

Answer 1

Exceptions in the Do_Work method also cause RunWorkerCompleted to be fired.