asked on
Ordinary program faster than Multithreading program!!!!!!!

I made a program to detect prime numbers starting from number 2 to 100000. First, I wrote it to support Multithreading since my processor has 6cores. The program finishes after 4386seconds. Then, I’ve change it to be Non-threading program which suppose to be slower. It finished after 201seconds!!!!!!!!!!
What the problem with my multi-threading program.

Note: I’m using Xeon X5680 processor which has 6 cores and support 12 threads.
File: Unit1.pas --------------------

unit Unit1; 

{$mode objfpc}{$H+}

interface

uses
  Classes, SysUtils, FileUtil, LResources, Forms, Controls, Graphics, Dialogs,
  StdCtrls;

type

    TShowStatusEvent = procedure(Status: String) of Object;

    { TMyThread }

    TMyThread = class(TThread)
    private
      fStatusText : string;
      InNumber : integer;

      FOnShowStatus: TShowStatusEvent;
      procedure ShowStatus;
    protected
      procedure Execute; override;
      function ISPrime(const vlNumber: Integer): Boolean;
    public
      IsPrimeFlage  : Boolean;
      PP : string;
      IsFinish : string;
      Constructor Create(CreateSuspended : boolean; InN:integer);
      property OnShowStatus: TShowStatusEvent read FOnShowStatus write FOnShowStatus;
    end;

  { TForm1 }

  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    Edit1: TEdit;
    Edit2: TEdit;
    Edit3: TEdit;
    Edit4: TEdit;
    Edit5: TEdit;
    Memo1: TMemo;
    ToggleBox1: TToggleBox;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure ToggleBox1Change(Sender: TObject);
    function DateTimeDiff(Start, Stop : TDateTime) : int64;
    function ISPrime2(const vlNumber: Integer): Boolean;
    procedure showtime;
  private
    { private declarations }
  public
    { public declarations }
  end; 

var
  Form1: TForm1; 

implementation
constructor TMyThread.Create(CreateSuspended : boolean; InN:integer);
  begin
    FreeOnTerminate := True;
    IsFinish := 'NO';
    IsPrimeFlage := False;
    PP := ' NO';
    InNumber:= InN;
    inherited Create(CreateSuspended);
  end;

  procedure TMyThread.ShowStatus;
  // this method is executed by the mainthread and can therefore access all GUI elements.
  begin
    if Assigned(FOnShowStatus) then
    begin
      FOnShowStatus(fStatusText);
    end;
  end;

  procedure TMyThread.Execute;
  var
    newStatus : string;
  begin
    fStatusText := 'NO';
    Synchronize(@Showstatus);
    fStatusText := 'NO';
    IsFinish := 'NO';
    while (not Terminated) do
      begin



      IsPrimeFlage := ISPrime(InNumber);
      if IsPrimeFlage then
         Pp := ' Yes';
      fStatusText := 'Yes';
      IsFinish := 'Yes';

      end;
  end;

    function TMyThread.ISPrime(const vlNumber: Integer): Boolean;
var
X: Integer;
vlPrime: Boolean;
begin
X := 2;
vlPrime := True;
While (X < vlNumber) and vlPrime do begin
vlPrime := ((vlNumber mod X) <> 0);
Inc(X);
end;
ISPrime := vlPrime;

  end;

{ TForm1 }

procedure TForm1.ToggleBox1Change(Sender: TObject);
var
   AAA : TMyThread;
begin
     AAA := TMyThread.Create(FALSE,2);

end;

function TForm1.DateTimeDiff(Start, Stop: TDateTime): int64;
var TimeStamp : TTimeStamp;
begin
  TimeStamp := DateTimeToTimeStamp(Stop - Start);
  Dec(TimeStamp.Date, TTimeStamp(DateTimeToTimeStamp(0)).Date);
  Result := (TimeStamp.Date*24*60*60)+(TimeStamp.Time div 1000);

end;

function TForm1.ISPrime2(const vlNumber: Integer): Boolean;
var
X: Integer;
vlPrime: Boolean;
begin
X := 2;
vlPrime := True;
While (X < vlNumber) and vlPrime do begin
vlPrime := ((vlNumber mod X) <> 0);
Inc(X);
end;
ISPrime2 := vlPrime;

end;

procedure TForm1.showtime;
var
i: real;
j: integer;
begin
i := frac(real(StrToTime('00:00:01')));
// i is the fractional number which Delphi uses to represent 1 second
// thus, dividing the full frac number Delphi uses to store any time by the i number,
//we will have the seconds, no?


Edit2.Text := inttostr(j);

end;

procedure TForm1.Button1Click(Sender: TObject);
var
   A1,A2,A3,A4,A5,A6,A7,A8,A9,A10,A11,A12 : TMyThread;
   i : integer;

   start, stop, elapsed : TDateTime;
begin
i := 1;
start := Now;
while i<=strtoint(Edit1.Text) do
begin
     A1 := TMyThread.Create(FALSE,i+1);
     A2 := TMyThread.Create(FALSE,i+2);
     A3 := TMyThread.Create(FALSE,i+3);
     A4 := TMyThread.Create(FALSE,i+4);



     A5 := TMyThread.Create(FALSE,i+5);
     A6 := TMyThread.Create(FALSE,i+6);
     A7 := TMyThread.Create(FALSE,i+7);
     A8 := TMyThread.Create(FALSE,i+8);


     A9 := TMyThread.Create(FALSE,i+9);
     A10 := TMyThread.Create(FALSE,i+10);
     A11 := TMyThread.Create(FALSE,i+11);
     A12 := TMyThread.Create(FALSE,i+12);

     WHILE not (a1.IsFinish = 'Yes') do
           Application.ProcessMessages;
     Memo1.Lines.Add(inttostr(i+1)+' ===>'+A1.pp);

     WHILE not (a2.IsFinish = 'Yes') do
           Application.ProcessMessages;
     Memo1.Lines.Add(inttostr(i+2)+' ===>'+A2.pp);


     WHILE not (a3.IsFinish = 'Yes') do
           Application.ProcessMessages;
     Memo1.Lines.Add(inttostr(i+3)+' ===>'+A3.pp);


     WHILE not (a4.IsFinish = 'Yes') do
           Application.ProcessMessages;
     Memo1.Lines.Add(inttostr(i+4)+' ===>'+A4.pp);




     WHILE not (a5.IsFinish = 'Yes') do
           Application.ProcessMessages;
     Memo1.Lines.Add(inttostr(i+5)+' ===>'+A5.pp);



     WHILE not (a6.IsFinish = 'Yes') do
           Application.ProcessMessages;
     Memo1.Lines.Add(inttostr(i+6)+' ===>'+A6.pp);


     WHILE not (a7.IsFinish = 'Yes') do
           Application.ProcessMessages;
     Memo1.Lines.Add(inttostr(i+7)+' ===>'+A7.pp);


     WHILE not (a8.IsFinish = 'Yes') do
           Application.ProcessMessages;
     Memo1.Lines.Add(inttostr(i+8)+' ===>'+A8.pp);

     WHILE not (a9.IsFinish = 'Yes') do
           Application.ProcessMessages;
     Memo1.Lines.Add(inttostr(i+9)+' ===>'+A9.pp);




     WHILE not (a10.IsFinish = 'Yes') do
           Application.ProcessMessages;
     Memo1.Lines.Add(inttostr(i+10)+' ===>'+A10.pp);

     WHILE not (a11.IsFinish = 'Yes') do
           Application.ProcessMessages;
     Memo1.Lines.Add(inttostr(i+11)+' ===>'+A11.pp);

      WHILE not (a12.IsFinish = 'Yes') do
           Application.ProcessMessages;
     Memo1.Lines.Add(inttostr(i+12)+' ===>'+A12.pp);

    stop := Now;
    elapsed := stop - start;

    Edit5.Text := IntToStr(DateTimeDiff(start,stop))+' sec';

    i := i+ 12;

         A1.Terminate;
         A2.Terminate;
         A3.Terminate;
         A4.Terminate;
         A5.Terminate;
         A6.Terminate;
         A7.Terminate;
         A8.Terminate;
         A9.Terminate;
         A10.Terminate;
         A11.Terminate;
         A12.Terminate;



end;

end;

procedure TForm1.Button2Click(Sender: TObject);
var
   i : integer;
   x:string;

   start, stop, elapsed : TDateTime;
begin
i := 2;
start := Now;
while i<=strtoint(Edit1.Text) do
begin
     if ISPrime2(i)then
        x :=' Yes'
     else
         x := ' No';

           Application.ProcessMessages;
     Memo1.Lines.Add(inttostr(i)+' ===>'+x);




    stop := Now;
    elapsed := stop - start;

    Edit5.Text := IntToStr(DateTimeDiff(start,stop))+' sec';

    i := i+ 1;





end;

end;

initialization
  {$I unit1.lrs}

end.


-------------------------------------------------------------------------
File: project1.lpr ------------------------------------------------------

program project1;

{$mode objfpc}{$H+}

uses
  {$IFDEF UNIX}{$IFDEF UseCThreads}
  cthreads,
  {$ENDIF}{$ENDIF}
  Interfaces, // this includes the LCL widgetset
  Forms, Unit1, LResources
  { you can add units after this };

{$IFDEF WINDOWS}{$R project1.rc}{$ENDIF}

begin
  {$I project1.lrs}
  Application.Initialize;
  Application.CreateForm(TForm1, Form1);
  Application.Run;
end.