Help with Threads

[lloydie2]

I am having my first foray into using threads, but I am coming unstuck when trying to use sql in one of the threads. I suspect That I am not creating an instance of the database connection.

Also I think I am also have a problem destroying the threads when I close the App. Can you Help?

Main Thread
===========================================
procedure TMyDataParse1.execute;
var
p: String;
EndStr, StrCheck: integer;
begin
Regex1 := TPerlRegEx.Create(nil);
Regex1.RegEx := RegExpStr1;
Regex1.Subject := FDataString;
if Regex1.Match then begin
StrCheck := 1;
if RegExpEnd1 = '1' then begin
EndStr := 1;
StrCheck := 0;
end
else
Endstr := 0;
StrCheck :=1;
end;
if RegExpEnd1 <> '1' then begin
Regex1.RegEx := RegExpEnd1;
Regex1.Subject := FDataString;;
if Regex1.Match then begin
EndStr := 1;
StrCheck := 0;
end
else begin
EndStr := 0;
StrCheck := 1;
end;
end;


if EndStr = 1 then begin
sysStr1 := sysStr1+FDataString;
CallString := CallConv(sysStr1,PhonesysID1);
CallString := CallString+',1,1';
Synchronize(SendCSVData);
EndStr := 0;
SysStr1 := '';
StrCheck := 0;
end
else begin
if StrCheck = 1 then
SysStr1 := SysStr1+FDataString+#13#10;
end;
end;

procedure TMyDataParse1.SendCSVData;
begin
TMyDataCalcuLate1.Create(CallString); // send data to new thread
Form1.SQLOutData(CallString);
end;
===================================================

TMyDataCalcuLate1.pas thread
===================================================
uses
Windows, Messages, SysUtils, Classes, Forms, Dialogs, DateUtils,StdCtrls,DB,passqlite, passql, ComCtrls;

Type
TMyDataCalcuLate1=class(TThread)
private
ThreadCollexDB : TliteDB;
FCalString: String;
SiteID,SysTimeBandStart, SysTimeBandEnd, SysOffset, SysTOffset :String;
CallInsert : Pchar;
public
constructor Create(CalString:String);
procedure execute; override;
function split(Text : string; Token : char ; WordNo : integer):string;
Procedure SendSql;
end;

implementation
uses
Unit1;
constructor TMyDataCalcuLate1.Create(CalString: String);
begin
FreeOnTerminate :=True;
FCalString := CalString;
inherited Create(False);
end;


Procedure TMyDataCalcuLate1.Execute;
var
debug : integer;
begin
Try
debug := 0;
With ThreadCollexDB do
Begin
ThreadCollexDB := TliteDB.Create(nil, ExtractFilePath(Application.ExeName)+'

http://www\collex.sdb');

end;
SIteID := '1';

{**************************************************
Get System setting from Database
***************************************************}
ThreadCollexDB.Query('SELECT * from sys_col where col_active = 1 and col_id ='''+SiteID+'''');
if ThreadCollexDB.RowCount > 0 then begin
SysTimeBandStart := ThreadCollexDB.Results[0][7];
SysTimeBandEnd := ThreadCollexDB.Results[0][8];
end;
end;
end
===================================================

 

[Glenn9999]

I tend to like the use of BeginThread much more than TThread. I don't know how much it applies to your situation, though, but I find it to be a lot easier to go with that call than to try to handle the IMO flawed thread implementation through TThread.

A description of it:

http://www.delphibasics.co.uk/RTL.asp?Name=BeginThread

 

[lloydie2]

Doh. Wrong Database name! I am still have a few problems when I close the app. I suspect I am opening a thread but not closing all the threads which are open. Do I need to force 'terminate'?

Do I need to create a destructor for each thread?

 

[Glenn9999]

If it might help, here's a small little demo program I did back when I was playing around with TThread before I found BeginThread. (code not related to threading cut out).

I don't think you have to forcibly terminate a thread within TThread if you use Create(False).

{ portions of a program written by Glenn9999 at tektips.com.  Purpose to demonstrate various tthread functions - puts an increasing count into a text label. }

type
  cthread = class(TThread)
  protected
  procedure doupdate;
  procedure execute;override;
  end;
var
  thread1: cthread;
  tno: integer;
  tbarmessage: string;
  minimized: boolean;

implementation

{$R *.DFM}

procedure cthread.doupdate;
  begin
    Application.Title := tbarmessage + IntToStr(tno);
    form1.label1.caption := IntToStr(tno);
  end;

procedure cthread.execute;
  var
    currentcount: integer;
  begin
    tbarmessage := 'Counting...';
    currentcount := 0;
    FreeOnTerminate := true;
    repeat
      inc(currentcount, 2);
      tno := currentcount;
      synchronize(doupdate);
    until Terminated;
  end;

procedure TForm1.Button5Click(Sender: TObject);
{ starts the thread process }
begin
  tno := 1;
  thread1 := cthread.create(false);
  thread1.priority := tpidle;
end;

end.

 

[lloydie2]

Thanks Glenn9999. I think I have the create(false) covered. I have managed to track down the offending thread. If I open my app and send some data to it, all seems to be fine. The problem I have is if I open the App and then close it without sending data.
For some reason the very first thread which is created cannot or is not destroyed on close. I am not sure what this thread is (probably the main thread for the app). Any Ideas?

 

[whosrdaddy]

I think you need to read more about threads. this one is a good primer :

http://codecentral.borland.com/Item.aspx?id=14809

download it from there, the original site is down...

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