Backgroundworker's RunWorkerCompleted event is firing even before completing the work

Question

I am using the BackgroundWorker thread to perform a long task(basically reading a big xml file). For the first time the worker works fine as desired, but if I upload a second xml file, using the same background worker it works fine sometimes but most of the time the Backgroundworker's RunWorkerCompleted is fired even before the DoWork event. Some of the code is displayed below

    private void openFile_Click(object sender, RoutedEventArgs e)
    {
          // Code removed for brevity
  worker = new BackgroundWorker();
            worker.RunWorkerAsync();
            worker.DoWork += new DoWorkEventHandler(worker_DoWork);
            worker.WorkerReportsProgress = true;
            worker.ProgressChanged += new ProgressChangedEventHandler(worker_ProgressChanged);
            worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(worker_RunWorkerCompleted);
       }

        void worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
    {
        DataImport();
        //worker.Dispose();
        //worker.Disposed += new EventHandler(worker_Disposed);
        //worker.DoWork -= worker_DoWork;
        //worker.RunWorkerCompleted -= worker_RunWorkerCompleted;
        //worker = null;
        //GC.Collect(GC.GetGeneration(worker), GCCollectionMode.Forced);
    }

worker is a globally defined variable. What is wrong here I am not getting. Kindly help

Answer 1

You should add the DoWork-event handler (and all other event handler, too) before calling RunWorkerAsync().

Otherwise, it could happen that RunWorkerAsync does practically nothing.