How USE Python4Delphi in multithreads

[Guest]

Hello, I can't use PYTHON4DELPHI in threads, errors keep popping up:

 

unit Unit1;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, pythonengine, System.syncobjs;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Memo1: TMemo;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
var
cs:TcriticalSection;
threads:integer;
begin
cs:=TcriticalSection.Create;
for threads :=0 to 5 do
TPythonThread.CreateAnonymousThread(
procedure
var
val:string;
Writer:TStreamWriter;
PythonEngine1:TPythonEngine;
begin
cs.Enter;
val:='';
cs.Leave;
PythonEngine1:=TPythonEngine.Create(nil);
PythonEngine1.LoadDll;
PythonEngine1.ExecString('fun=("Hello World")');
val:=( 'Value = ' + PythonEngine1.EvalStringAsStr('fun')  );
FreeAndNil(PythonEngine1);
form1.Memo1.Lines.Add(val);
TPythonThread.Synchronize(nil,
procedure
begin
Writer := TStreamWriter.Create(Extractfilepath(paramstr(0))+'TEST'+'.txt',
true, TEncoding.Ansi);
Writer.WriteLine(val);
Writer.Free;
end);
end).Start;
end;
end.

 

[Soulflesh 1]

Hi uefi,

 

have a look at Running Python scripts in threads - Python4Delphi - Delphi-PRAXiS [en] (delphipraxis.net).

Unfortunately, this still does not work in the form of true parallelism at the moment. Only the pseudo Python thread parallelism. From my point of view, there is currently only the possibility/attempt to multiply the Python dlls and load them per thread.

 

Bets regards

[David Heffernan 2345]

You should read about the Python GIL which is liable to be an issue

[pyscripter 689]

8 hours ago, uefi said:

I still don’t understand how you did it and where to insert it
Py_Begin_Allow_Threads; and Py_End_Allow_Threads;

Use Demo 33 as a guide.  As @David Heffernan said running python in threads is not trivial and unlikely to save you time.