Application.ProcessMessages hangs???
- by X-Ray
my single threaded delphi 2009 app (not quite yet complete) has started to have a problem with Application.ProcessMessages hanging. my app has a TTimer object that fires every 100 ms to poll an external device. i use Application.ProcessMessages to update the screen when something changes so the app is still responsive.
one of these was in a grid OnMouseDown event. in there, it had an Application.ProcessMessages that essentially hung. removing that was no problem except that i soon discovered another Application.ProcessMessages that was also blocking.
i think what may be happening to me is that the TTimer is--in the app mode i'm currently debugging--probably taking too long to complete. i have prevented the TTimer.OnTimer event hander from re-entering the same code (see below):
procedure TfrmMeas.tmrCheckTimer(Sender: TObject);
begin
if m_CheckTimerBusy then
exit;
m_CheckTimerBusy:=true;
try
PollForAndShowMeasurements;
finally
m_CheckTimerBusy:=false;
end;
end;
what places would it be a bad practice to call Application.ProcessMessages? OnPaint routines springs to mind as something that wouldn't make sense.
any general recommendations?
i am surprised to see this kind of problem arise at this point in the development!
