Please search the issue tracker on github for shutdown related issues. This was discussed extensively.

There is WIP pull request worked on by 3 people to support this reloading scenario in Unity.


On Wed, Oct 3, 2018, 9:50 PM Ron Harding via PythonDotNet <pythondotnet@python.org> wrote:
Did you try background or threadpool threads? Redirected process calls and looking for stdin stdout stderr streams allows more control.


On Wed, Oct 3, 2018 at 15:47, Luke, Steve

I am getting a crash trying to embed Python into my VB program using Python for .NET.  The goal of my application is to allow users to run their own python scripts inside a larger application.  The crash I am getting happens the second time I run a script that imports certain large libraries (like numpy or scikit-image) but does not affect all libraries (for example PIL).

 

My environment:

Windows 10 Pro x64, Python 3.6.5 (in Anaconda), Python for .Net 2.4.0 (installed from git’s master branch).

 

Here is the VB code:

    Public Function Startup(ByRef param As String) As Integer

        PythonEngine.Initialize()

        'mm.PrintMsg(PythonEngine.BuildInfo)

        'mm.PrintMsg(PythonEngine.Compiler)

        'mm.PrintMsg(PythonEngine.Platform)

        'mm.PrintMsg(PythonEngine.ProgramName)

        'mm.PrintMsg(PythonEngine.PythonHome)

        'mm.PrintMsg(PythonEngine.PythonPath)

        Using (Py.GIL())

 

            Dim scriptPath As String = param

 

            Dim scriptDir As String = Path.GetDirectoryName(scriptPath)

            Dim scriptName As String = GetPythonModuleName(scriptPath)

            Dim scriptParam As String = ""

 

            Dim scriptScope As PyScope = Py.CreateScope()

 

            Dim scriptText As String = My.Computer.FileSystem.ReadAllText(scriptPath)

            scriptScope.Exec(scriptText)

 

            If scriptScope.Contains(STARTUP_METHOD_NAME) Then

                scriptScope.Exec(String.Format("{0}(r'{1}')", STARTUP_METHOD_NAME, scriptParam))

            End If

 

            scriptScope.Dispose()

        End Using

        PythonEngine.Shutdown()

 

        Return 0

    End Function

 

And this is the Python script I am running:

import skimage.io

 

def Startup(param):

    pass

 

def Docommand(param):

    pass

   

def Shutdown():

    pass

 

When I run it the VB code the first time, things work great.  When I run the VB code a second time (without first restarting the entire application) I get an access violation exception on the scriptScope.Exec() call:

Exception: System.AccessViolationException :

Message: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

Source: Python.Runtime

StackTrace:

   at Python.Runtime.Runtime.PyObject_Call(IntPtr pointer, IntPtr args, IntPtr kw)

   at Python.Runtime.ImportHook.__import__(IntPtr self, IntPtr args, IntPtr kw)

   at Python.Runtime.Runtime.PyObject_Call(IntPtr pointer, IntPtr args, IntPtr kw)

   at Python.Runtime.ImportHook.__import__(IntPtr self, IntPtr args, IntPtr kw)

   at Python.Runtime.Runtime.PyObject_Call(IntPtr pointer, IntPtr args, IntPtr kw)

   at Python.Runtime.ImportHook.__import__(IntPtr self, IntPtr args, IntPtr kw)

   at Python.Runtime.Runtime.PyObject_Call(IntPtr pointer, IntPtr args, IntPtr kw)

   at Python.Runtime.ImportHook.__import__(IntPtr self, IntPtr args, IntPtr kw)

   at Python.Runtime.Runtime.PyObject_Call(IntPtr pointer, IntPtr args, IntPtr kw)

   at Python.Runtime.ImportHook.__import__(IntPtr self, IntPtr args, IntPtr kw)

   at Python.Runtime.Runtime.PyObject_Call(IntPtr pointer, IntPtr args, IntPtr kw)

   at Python.Runtime.ImportHook.__import__(IntPtr self, IntPtr args, IntPtr kw)

   at Python.Runtime.Runtime.PyObject_Call(IntPtr pointer, IntPtr args, IntPtr kw)

   at Python.Runtime.ImportHook.__import__(IntPtr self, IntPtr args, IntPtr kw)

   at Python.Runtime.Runtime.PyObject_Call(IntPtr pointer, IntPtr args, IntPtr kw)

   at Python.Runtime.ImportHook.__import__(IntPtr self, IntPtr args, IntPtr kw)

   at Python.Runtime.Runtime.PyObject_Call(IntPtr pointer, IntPtr args, IntPtr kw)

   at Python.Runtime.ImportHook.__import__(IntPtr self, IntPtr args, IntPtr kw)

   at Python.Runtime.Runtime.PyRun_String(String code, IntPtr st, IntPtr globals, IntPtr locals)

   at Python.Runtime.PyScope.Exec(String code, IntPtr _globals, IntPtr _locals)

   at MyApp.MyClass.Startup(String& param) in C:\Git\MyPath\MyApp.vb:line 132

 Unfortunately the stack trace doesn't show line numbers for anything in the Python.Runtime.

 

Interestingly, if you look at the VB code, I have some lines of commented out code:

        'mm.PrintMsg(PythonEngine.BuildInfo)

        'mm.PrintMsg(PythonEngine.Compiler)

        'mm.PrintMsg(PythonEngine.Platform)

        'mm.PrintMsg(PythonEngine.ProgramName)

        'mm.PrintMsg(PythonEngine.PythonHome)

        'mm.PrintMsg(PythonEngine.PythonPath)


Since the app doesn’t have a console, this sends the text to the enclosing app for display.  If I uncommon that code, then the first time I run it I get:

default, Mar 29 2018, 13:32:41

[MSC v.1900 64 bit (AMD64)]

win32

python

 

F:\Anaconda3\python36.zip;F:\Anaconda3\Lib;F:\Anaconda3\DLLs;C:\MX6

 

And the second time I run it I get:

default, Mar 29 2018, 13:32:41

[MSC v.1900 64 bit (AMD64)]

win32

pyth???

???

F:\Anaconda3\python36.zip;F:\Anaconda3\Lib;F:\Anaconda3\DLLs;C:\MX6

 

And the application doesn’t crash!  Instead it just says the skimage module can’t be found.  Notice the bolded lines (bold added after the fact).  The program name and python home values are being corrupted.

Is there something I am doing wrong as far as taking down the PythonEngine such that it could be put back up in an as-new state later on?



Steve


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