[RESOLVED] Windows Threaded console app issue?
lazarus / 8-Other

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DGambrinus · 2009-05-08 14:28

Hello all. I've recently had to port a Linux app to the Windows world
for work and I'm running into an annoyance. This app is a console app
that runs threads every now and again and it would seem that once you
create a thread in a FPC console app that the explorer shortcut
(Windows+E) doesn't work until the application is killed. (Other
Windows key shortcuts work though. Win+R, Win+D)

Before the thread is launched it works great. If you hit Win+E after
the thread is launched nothing happens except your taskbar/start menu
doesn't respond to anything. When the app closes your taskbar/start
menu comes back and then you do get the number of explorer windows
corresponding to the number of times you pressed "Win+E".

I've tested on a few machines (all WinXP as that is the target
environment) and it seems to be consistent. Just wondering if I am
doing something dumb or if I should submit a bug report. The same code
in Delphi doesn't have the same issue.

FPC: 2.2.2
Lazarus: 0.9.26
OS: WinXP fully patched.

Here is code for a test app.
This app just counts to ten, launches a thread that stays alive for 8
seconds, and then closes 2 seconds after that. Win+E works up until
the thread is launched at second 10 and doesn't work until the app
closes at 20 seconds.
Code: [Select]//------------------------------------------------------
--------------------------------------------------------------------
program project1;



{$mode objfpc}{$H+}



uses

  {$IFDEF UNIX}{$IFDEF UseCThreads}

  cthreads,

  {$ENDIF}{$ENDIF}

  Classes, sysutils

  { you can add units after this };



type



  { TDummyThread }



  TDummyThread = class(TThread)

  private

  protected

    procedure Execute; override;

  public

    constructor Create;

  end;



{ TDummyThread }



procedure TDummyThread.Execute;

var

  i: Integer;

begin

  i := 0;



  while i < 8 do

  begin

    Sleep(1000);

    inc(i);

  end;



  WriteLn('Thread terminated!');

  self.Terminate();

end;



constructor TDummyThread.Create;

begin

  Self.FreeOnTerminate := True;

  inherited Create(True);

end;



var

  i: Integer;

  t: TDummyThread;

begin

  i := 0;



  while i < 20 do

  begin

    if (i < 10) then

      Writeln('Starting thread in ' + inttostr(10 - i) + '
seconds...')

    else if (i = 10) then

    begin

      WriteLn('Starting thread! Does WIN+E work?);

      t := TDummyThread.Create();

      t.Resume();

    end

    else

      WriteLn('Closing in ' + inttostr(20 - i) + ' seconds.');



    Sleep(1000);

    inc(i);

  end;


end.

//--------------------------------------------------------------------
------------------------------------------------------

Thanks for any insight.
--Sam

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clauslack · 2009-05-10 02:01

With Application.ProcessMessages works, but only in LCL/FreePascal
Application

Maybe FreePascal not process messages from Windows.

Look at this (form.pas), with a Memo and Button

unit form;
{$mode objfpc}{$H+}
interface
uses   Classes, SysUtils, FileUtil, LResources, Forms, Controls,
StdCtrls;

type
  { TForm1 }
  TForm1 = class(TForm)
    Button1: TButton;
    Memo1: TMemo;
    procedure Button1Click(Sender: TObject);
  private
    { private declarations }
  public
    { public declarations }
  end;
 TDummyThread = class(TThread)
  private
  protected
  procedure Execute; override;
  public
   constructor Create;
  end;

var   Form1: TForm1;

implementation
{ TForm1 }

procedure TDummyThread.Execute;
var  i: Integer;
begin
  i := 0;
  while i < 8 do
   begin
     Sleep(1000);
     inc(i);
     Application.processmessages;
   end;
  // WriteLn('Thread terminated!');
   self.Terminate();
end;

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

procedure TForm1.Button1Click(Sender: TObject);
var   i: Integer;   t: TDummyThread;
begin
  i := 0;
  while i < 20 do
  begin
    if (i < 10) then
      memo1.lines.add('Starting thread in ' + inttostr(10 - i) + '
seconds...')
    else if (i = 10) then
    begin
      memo1.lines.add('Starting thread! Does WIN+E work?');
      t := TDummyThread.Create();
      t.Resume();
    end
    else    memo1.lines.add('Closing in ' + inttostr(20 - i) + '
seconds.');
    Sleep(1000);
    Application.processmessages;
    inc(i);
end;
end;
initialization
  {$I form.lrs}

end.

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DGambrinus · 2009-05-11 11:55

Thanks for looking into it, Clauslack!

Yes, LCL apps seem to work fine. I can't think of anything that the
end user actually needs to know about this app so I don't have a GUI.
I may post as a FPC bug and see what they say. I just don't know if it
is a FPC thing or a Windows thing.

----------------------------------------------------------------------
DGambrinus · 2009-05-11 17:48

I submitted this as a potential bug to the FPC folks. (Issue # 0013688
in the bug tracker.) It has been fixed in the compiler version 2.3.1
which is currently unstable. I recompiled with the new compiler and it
has indeed fixed this issue.

http://bugs.freepascal.org/view.php?id=13688