How do I tell when all threads in a pool are complete

How do I tell when all threads in a pool are complete

• Bill Byrnes

  Yarg.

  I created a new thread that does cleanup - the function looks like this:

  private void Cleanup(object key)

  {
  _ewh.WaitOne();
  for (int i = listView1.Items.Count - 1; i > -1; i--)
  {
  if (_InvokeGetListView(i, 1) == "Dead")
  _InvokeRemoveListItem(i);
  }
  }

  At the end of all of my other threads I do this check in the finally statement:

  finally

  {
  tc--;
  if (tc == 0 && ats)
  _ewh.Set();
  }

  I got the cross-threading error again, so I hacked those invoke functions. This sure would be a lot easier if I could run the cleanup from the main thread. As it is, the invoke function is returning an error - return type must be able to be converted to a string or something like that. I have no idea what to do about this because I don't understand the invoke/delegate thing.

  private delegate string _InvokeGetListViewDelegate(int _row, int _column);

  private string _InvokeGetListView(int _row, int _column)

  {

  // If it's coming from another thread, Invoke _InvokeToListView trough the _InvokeToListViewDelegate and end this thing.

  if (this.InvokeRequired) { this.Invoke(new _InvokeGetListViewDelegate(_InvokeGetListView), _row, _column); return; }

  // If it passed that last test, then it's either coming from the form's own thread or invoked from another thread, and the stuff can be edited safely.

  return listView1.Items[_row].SubItems[_column].Text;

  }

  private delegate void _InvokeRemoveListItemDelegate(int _row);

  private void _InvokeRemoveListItem(int _row)

  {

  // If it's coming from another thread, Invoke _InvokeToListView trough the _InvokeToListViewDelegate and end this thing.

  if (this.InvokeRequired) { this.Invoke(new _InvokeRemoveListItemDelegate(_InvokeRemoveListItem), _row); return; }

  // If it passed that last test, then it's either coming from the form's own thread or invoked from another thread, and the stuff can be edited safely.

  listView1.Items[_row].Remove();

  }

  
  

• Oleg_Ivanov

  Slick.
  

• TANWare

  Create an integer that stores how many threads are running.
  At the beginning of the threads that need to be counted, add 1 to this integer.
  At the end of those threads, remove 1, and if it's 0 after removing AND all threads have started (create a bool for this too, to flag that every needed thread is started), then all threads have done their work (and set the all-started bool to false).
  
  Backwards
  for (int i = listView1.Items.Count -1; i > -1; i--)
  {
  // listView1.Items[i].
  }
  
  
  

• stupots

  nah, don't do while(bool){thread.sleep()} things.
  Put one of these in your code somewhere:
  System.Threading.EventWaitHandle _ewh = new System.Threading.EventWaitHandle(false, System.Threading.EventResetMode.AutoReset);
  
  The thread that needs to wait (don't do this on UI thread) till everything's done does this:
  _ewh.WaitOne();
  
  The last thread (the one where all threads started and the integer is 0) does:
  _ewh.Set();
  to let the waiting thread continue it's work.
  
  That's one of the clean ways to let a thread wait for another thread. :)
  
  
  

• Romek

  if (this.InvokeRequired) { return this.Invoke(new _InvokeGetListViewDelegate(_InvokeGetListView), _row, _column); /* and remove return here (which returned something (null) to ignore the stuff below) */}

  i'm not sure if that really works, try playing around with the invoke thing a bit, cause you need to get the parameter trough the invoke that is done up there ;)

  but i don't think invoke is needed when just reading some text.

  
  
  

• M. Leary

  Would it make the most sense to have that cleanup process run in the last thread then I thought it would be cleaner to have it run from the main thread so I wouldn't have to figure out that invoke/delegate nonsense for the delete :) can I create a do -while integer > 0 sleep function in the main thread, then perform the cleanup after it exits this loop Is there a more elegant way

  
  
• How do I tell when all threads in a pool are complete