Question

I have to work with legacy code. This code has a TTimer created in a main thread.
In OnTimer event the timer is checking periodically a state of some data in the worker thread.

pseudocode:

procedure MainForm.OnTimer(Sender: TObject);
begin
  if WorkerThread.Data.State = full then
  begin
    WorkerThread.Free; //This freezes GUI.    
  end else
   //Do something else.
end;

The problem is that I want to do some background operation when the WorkerThread is terminating. To avoid synchronization I’ve overriden DoTerminate method. However in this particular case, this is not helping and my GUI becomes frozen until the DoTerminate finishes.

Can I somehow avoid the freeze?

Thanks.

Answer 1

There’s not enough code here to say anything with any certainty. However, calling Free on a thread results in a call to Terminate followed by a WaitFor. It’s quite plausible that the wait is not returning which would be consistent with the frozen UI.