Freeing resources when thread is not alive

Question

I am using BackgroundWorker and inside it I am using foreach loop, inside which i create new thread, wait for it to finish, and than report progress and continue foreach loop. H

Answer 1

This might be cause garbage collection is not immediate. Try to collect after the thread goes out of scope:
Edit:
You also need to implement a better way to wait for the thread to finish other then busy wait(while (thread.IsAlive);) to save CPU time, you can use AutoResetEvent.

private void DoWork(object sender, DoWorkEventArgs e) {
            var fileCounter = Convert.ToDecimal(fileNames.Count());
            decimal i = 0;
            var Event = new AutoResetEvent(false);
            foreach (var file in fileNames) {
                i++;
                var generator = new Generator(assembly);

                {
                    var thread = new Thread(new ThreadStart(
                            delegate() {
                                generator.Generate(file);
                                Event.Set();
                            }));
                    thread.SetApartmentState(ApartmentState.STA);
                    thread.Start();
                    //while (thread.IsAlive); // critical point
                    Event.WaitOne();
                }
                GC.Collect();
                int progress = Convert.ToInt32(Math.Round(i / fileCounter * 100));
                backgroundWorker.ReportProgress(progress);
            }
        }