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No juice for threads started with thread.start_new in Python
Joined: 21 Dec 2006
Posts: 8
No juice for threads started with thread.start_new in Python
When I start a python thread from within a VarPyth call into Python ..
//Delphi
dcore.StartJob(dcore.somethread)
.. the thread.start_new started thread there doesn`t do something
unless I feed Python (GIL?) from the main delphi thread with
dcore.time.sleep(0.1) or frequent Python execution or so - which means
no real parallel execution of Delphi and Python thread.
Seems the GIL/Thread lock is not released by default.
How to cure this?
Is there just some PyEval_InitThreads( ) / PyEval_SaveThread() /
PyEval_RestoreThread() processing missing in TPythonEngine & VarPyth
processing?
( P4D v3.25, Py2.3 )
Robert
Joined: 22 May 2006
Posts: 6
No juice for threads started with thread.start_new in Python
PythonEngine acquires the GIL when initialized.
to allow other threads to run you need to release it, when you are
finished with calling python from delphi.
i found the easiest way is to use the PyEval_SaveThread /
PyEval_RestoreThread API methods and saving a threadstate for your
main thread.
codewise, that`s:
var
myThreadState: PPyThreadState;
// call python from your delphi main thread
//...
myThreadState:=GetPythonEngine.PyEval_SaveThread;
// other threads are allowed to run
//....
GetPythonEngine.PyEval_RestoreThread(myThreadState);
// calls to python from your main delphi thread allowed again
//....
hope this helps
Samuel
--- In pythonfordelphi@yahoogroups.com, "kxroberto" <kxroberto@...> wrote:
>
> When I start a python thread from within a VarPyth call into Python ..
>
> //Delphi
> dcore.StartJob(dcore.somethread)
>
>
> .. the thread.start_new started thread there doesn`t do something
> unless I feed Python (GIL?) from the main delphi thread with
> dcore.time.sleep(0.1) or frequent Python execution or so - which means
> no real parallel execution of Delphi and Python thread.
> Seems the GIL/Thread lock is not released by default.
>
> How to cure this?
>
> Is there just some PyEval_InitThreads( ) / PyEval_SaveThread() /
> PyEval_RestoreThread() processing missing in TPythonEngine & VarPyth
> processing?
>
> ( P4D v3.25, Py2.3 )
>
>
> Robert
>
Joined: 21 Dec 2006
Posts: 8
No juice for threads started with thread.start_new in Python
Thanks. Found that when one uses the VarPyth Interface intensively
throughout the app (and doing the PyEval_SaveThread.. everytime is
tedious) its more easy to do it through an Application.OnIdle like:
procedure MyIdleHandler(Sender: TObject; var Done: Boolean);
begin
dcore.retrieve_interthreadcalls();
dcore.time.sleep(0.005);
Done:=False; //forces continuous processing
end;
.. which feeds Python threading through time.sleep as well - whenever
the GUI doesn`t do something else.
(And possibly feed Python also through a timer or explicitely during
modal message loops and do PyEval_SaveThread.. only when there are
expensive computations.
Robert
--- In pythonfordelphi@yahoogroups.com, "samuel_iseli"
<samuel.iseli@...> wrote:
>
> PythonEngine acquires the GIL when initialized.
> to allow other threads to run you need to release it, when you are
> finished with calling python from delphi.
>
> i found the easiest way is to use the PyEval_SaveThread /
> PyEval_RestoreThread API methods and saving a threadstate for your
> main thread.
>
> codewise, that`s:
>
> var
> myThreadState: PPyThreadState;
>
> // call python from your delphi main thread
> //...
> myThreadState:=GetPythonEngine.PyEval_SaveThread;
> // other threads are allowed to run
> //....
> GetPythonEngine.PyEval_RestoreThread(myThreadState);
> // calls to python from your main delphi thread allowed again
> //....
>
> hope this helps
> Samuel
>
> --- In pythonfordelphi@yahoogroups.com, "kxroberto" <kxroberto@> wrote:
> >
> > When I start a python thread from within a VarPyth call into Python ..
> >
> > //Delphi
> > dcore.StartJob(dcore.somethread)
> >
> >
> > .. the thread.start_new started thread there doesn`t do something
> > unless I feed Python (GIL?) from the main delphi thread with
> > dcore.time.sleep(0.1) or frequent Python execution or so - which means
> > no real parallel execution of Delphi and Python thread.
> > Seems the GIL/Thread lock is not released by default.
> >
> > How to cure this?
> >
> > Is there just some PyEval_InitThreads( ) / PyEval_SaveThread() /
> > PyEval_RestoreThread() processing missing in TPythonEngine & VarPyth
> > processing?
> >
> > ( P4D v3.25, Py2.3 )
> >
> >
> > Robert
> >
>
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