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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