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TThread collapses application

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fatg:
I've made a very very simple TThread descendant, here is the source:


--- Code: ---
  TTestThread = class(TThread)
  protected
    procedure Execute; override;
  public
    constructor Create;
  end;

implementation

constructor TTestThread.Create;
begin
  inherited Create(True);
  FreeOnTerminate := True;
end;

procedure TTestThread.Execute;
begin
  Sleep(1000);
end;


--- End code ---


I am testing it with this code:



--- Code: ---

var
  ThreadCount: Integer;

procedure TForm1.ThreadOnTerminate(Sender: TObject);
begin
  Dec(ThreadCount);
  Label1.Caption := IntToStr(ThreadCount);
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  ThreadCount := 0;
  Label1.Caption := IntToStr(ThreadCount);
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  with TTestThread.Create do
  begin
    Inc(ThreadCount);
    Label1.Caption := IntToStr(ThreadCount);

    OnTerminate := @ThreadOnTerminate;
    Resume;
  end;
end;

--- End code ---


This simple example collapses my application every time. Sometimes the second thread destroys it, other times it's seventh. They don't have to run consequently, the application terminates even if I create one thread at a time with waits between them. Clicking very fast produces a lot of threads, although it collapses long before I come to 32 (I can produce 32 threads with fast-clicking in the same application in Delphi6 without problems).

This test was ran in Delphi6 several times. No errors occurred, although I am aware of the danger of accessing ThreadCount variable and Label1 component without locking.

Is this an FCL error, do you think it's a bug or is the error on my side? Does the same thing happen to you?

Best regards,
G

IgD:
Fatq, Delphi 7 comes with a threads demo.  It does some visual sorting routines.  Have you tried porting it to Lazarus for testing?  That would be a great diagnostic tool.

fatg:
Thanks for the suggestion, I've ported D6 Threads demo, here it is:

http://pzs.asit.si/data/threads.rar
exe included

It proves that TThread is very unstable in fpc.

fatg:
Oh, and my nick is fatg, not fatq. Not that it really matters, I've just notices the underline font style completely hides the difference between g and q. And you also have the same problem :)

Anonymous:
Excellent work!  I wonder who from the Lazarus team can check this out.

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