Hello lazarus-list,

I'm working in a program that needs multiple threads and one will synchronize with main thread to display a log. I do not wish to continue the caller thread meanwhile the Synchronize has not been finished, so I had added a set of events to handle this. My program locks up just after start, and the offended method is in the Synchronize feature. So I start to rewrite the same idea around the multithread example code keeping only the things that I need, and to ask to you if this is a Synchronize bug/problem or a non-wanted programming technique, and I must replace the code with a different approach (if possible).

The main problem is here, in the execute method:

-----------------------------------------
procedure TMyThread.Execute;
begin
  fStatusText := 'TMyThread Starting...';
  Synchronize(@Showstatus);
  fStatusText := 'TMyThread Running...';
  while (not Terminated) and (true {any condition required}) do begin
    m_Event.WaitFor(1000); //It should be INFINITE...
    m_Event.ResetEvent;
    if NewStatus  fStatusText then begin
      m_Lock.Enter;
      fStatusText := newStatus;
      Synchronize(@Showstatus);
      m_Lock.Leave;
    end;
    m_EventDone.SetEvent;
  end;
end;
-----------------------------------------

The idea is to modify "NewStatus" from an outside procedure (CriticalSection protected) and activate m_Event to let the Execute know that it must launch the syncronize, then it will wait for "m_EventDone" to be signaled before continue.

Attached is the Multithread example mainunit.pas modified with my changes to raise the bug/problem, simply replace the example file with this one.

System: WinXP SP2
Lazarus: 0.9.24 and 0.9.25 #13510 (packages from the web) FPC: As shipped with lazarus 2.2.0 and 2.2.1
CPU: Pentium Hyperthreading (tested without hyper too).