[fpc-devel] Re: I get duplicate GUIDs under Linux

[Graeme Geldenhuys]

Hi,

I just tested that same code under Windows 2000 and I don't have any
errors or duplicates. As I would have expected.  So there seems to be
a bug in the CreateGUID implementation of Linux.

BTW:
  I'm using Ubuntu 7.10.  My 'uname -a' output:
  Linux graemeg 2.6.22-14-generic #1 SMP Tue Feb 12 07:42:25 UTC 2008
i686 GNU/Linux


Regards,
  - Graeme -


On 29/05/2008, Graeme Geldenhuys <graemeg.lists at gmail.com> wrote:
> Hi,
>
>  I'm trying to do performance testing in Firebird RDBMS using GUID's
>  and primary keys. I constantly got PK violations. I then wrote the
>  code show below to create 50,000 GUID's and add them to a StringList
>  (no duplicates allowed). Every time I run this I get a duplicate GUID
>  at iteration 1021.  My original test is supposed to create 5mil
>  records, but I can't get past 1000! :-(
>
>  Actual program output:
>
>  graemeg at graemeg:index_performance$ ./index_performance.elf
>  Duplicate value detected: {FD3DF19D-A878-F8BA-F9D1-108658451E05}
>   List.Count = 1021
>
>  GUID's are supposed to be very unique! Wikipedia says something like:
>  Create a billion every second for 10 years or something before you
>  deplete the range.
>  So what is wrong with my code or maybe the Free Pascal implementation?
>
>  --------------------[ code ]------------------------------
>  procedure TMainForm.btnTestClicked(Sender: TObject);
>  var
>   sl: TStringList;
>   s: string;
>   i: integer;
>   d: integer;
>   guid: TGUID;
>  begin
>   sl := TStringList.Create;
>   try
>     try
>       sl.Sorted := True;
>       sl.Duplicates := dupError;
>       for i := 1 to 50000 do
>       begin
>         CreateGUID(guid);
>         s := GUIDToString(guid);
>         sl.Add(s);
>       end;
>       writeln('Created 50,000 GUIDs');
>     except
>       on e: EStringListError do
>       begin
>         writeln('Duplicate value detected: ' + s);
>         writeln('  List.Count = ', sl.Count);
>       end;
>       on e: Exception do
>         writeln('Unknown error: ', e.Message);
>     end;
>   finally
>     sl.Free;
>   end;
>  end;
>  --------------------[ end ]--------------------------------
>
>
>  Changing the line that adds the GUID to the StringList by prefixing
>  the counter, all is fine. So I can't see a problem in my code.
>
>    sl.Add(IntToStr(i) + s);
>
>
>  Regards,
>   - Graeme -
>
>
>  _______________________________________________
>  fpGUI - a cross-platform Free Pascal GUI toolkit
>  http://opensoft.homeip.net/fpgui/
>


-- 
Regards,
  - Graeme -


_______________________________________________
fpGUI - a cross-platform Free Pascal GUI toolkit
http://opensoft.homeip.net/fpgui/