Mailman 3 September 2014 - Python.NET

Multithreading/multiprocessing
by Alan Macdonald May 5, 2025

May 5, 2025

Hello, has anyone successfully used multithreading or multiprocessing with Python.Net? I tried to multi-thread from the .Net side and the Python.Net libraries seem to have issues in the RunScript method. I had to take an implementation off the web of that method because the shipped method doesn’t seem to work. I then had a working multi-processing example from CPython that I tried from Python.Net but it gives an error 'module' object has no attribute 'argv' When trying to create a process pool by executing the line pool = Pool(processes=4) Is it possible to do multithreading or multiprocessing with Python.Net? Thanks, Alan

2 1

How to embed properly using Python for .NET
by Denis Akhiyarov Oct. 6, 2014

Oct. 6, 2014

When I try to use PythonEngine.ImportModule(mymodulename) some of the optional modules in dependencies are attempted to be loaded (not required for module use without embedding). This results in return null from this method because some of these optional dependencies are not required and hence not available. What is the proper method to use in this PythonNET API for loading user-written module which depends on multiple other modules? I tried importhook.cs from both versions: https://github.com/pythonnet/pythonnet https://github.com/renshawbay/pythonnet http://stackoverflow.com/questions/25101718/how-to-embed-properly-using-pyt…

2 3

Python.Net for Python3: bug when using an embedded interpreter
by Serge WEINSTOCK Oct. 2, 2014

Oct. 2, 2014

Hi Tony, You recently made a change which prevents me using the library in an embedded Python interpreter. In pythonengine.cs, you "inject" decorators with the following code: //================================================================= public static void Initialize() { ..... IntPtr globals = Runtime.PyEval_GetGlobals(); PyDict locals = new PyDict(); try { IntPtr builtins = Runtime.PyEval_GetBuiltins(); Runtime.PyDict_SetItemString(locals.Handle, "__builtins__", builtins); var assembly = Assembly.GetExecutingAssembly(); using (Stream stream = assembly.GetManifestResourceStream("Python.Runtime.resources.clr.py")) using (StreamReader reader = new StreamReader(stream)) { // add the contents of clr.py to the module string clr_py = reader.ReadToEnd(); PyObject result = RunString(clr_py, globals, locals.Handle); if (null == result) throw new PythonException(); result.Dispose(); } //================================================================= When running from a Python script, it's fine because the Python interpreter has already been initialized and global variables have been defined. The issue is that when running from an embedded interpreter. As I must first initialize the Python engine using PythonEngine.Initialize(). So when we reach this piece of code, there is no script running, no "Python context", so "PyEval_GetGlobals" returns null and "RunString" fails. We could create an artificial global dictionary but it won't be available to the rest of the code. I think it should be best to move this code into a Python module. If run from a script (PyEval_GetGlobals() != null), you could inject the decorators with a simple "from decorators_pythonnet import *". If run from an embedded interpreter, we could add a line for running the same code once the engine has been initialized. What do you think? Serge Weinstock ___________________________________________________________ This e-mail may contain confidential and/or privileged information. If you are not the intended recipient (or have received this e-mail in error) please notify the sender immediately and delete this e-mail. Any unauthorised copying, disclosure or distribution of the material in this e-mail is prohibited. Please refer to http://www.bnpparibas.co.uk/en/email-disclaimer/ for additional disclosures.

2 3

Re: [Python.NET] Python.Net for Python3: bug when converting a PyLong
by Callum Noble Sept. 30, 2014

Sept. 30, 2014

Hi Serge, Did you file a pull request for this one? I'm interested in the fix too...

2 1

Python.Net for Python3: bug when converting a PyLong to a System.Int32
by Serge WEINSTOCK Sept. 26, 2014

Sept. 26, 2014

Hi Tony, I've found a bug when trying to use Python integer as .Net int32. For example: //======================================================================= using System; using Python.Runtime; namespace TestPythonNet { public class ATest { public long a64; public int a32; public void f32(int a) { Console.WriteLine("got int {0}", a);} public void f64(long a) { Console.WriteLine("got long {0}", a); } } class Program { static void Main(string[] args) { PythonEngine.PythonHome = @"D:\src\scratch\TestPythonNet\TestPythonNet\PythonRuntime"; PythonEngine.ProgramName = "PythonRuntime"; PythonEngine.Initialize(); PythonEngine.ImportModule("clr"); using (Py.GIL()) { try { PythonEngine.RunSimpleString( @" import clr clr.AddReference('TestPythonNet') from TestPythonNet import ATest f = ATest(); f.a64 = 10 # OK f.a32 = 10 # Fails! f.f64(-1) # OK f.f32(-1) # Fails! print('all fine!') "); } catch (PythonException e) { Console.WriteLine(e); } } } } } //======================================================================= All the call from python using integer as .Net int will fail. This is due to the fact that python3 has only one type of integer: int64. Furthermore, in the Python C API, all the conversion functions from or to int32 have disappeared. I think that the following patch fixes the issue: Src/runtime/converter.cs //======================================================================= static bool ToPrimitive(IntPtr value, Type obType, out Object result, bool setError) { IntPtr overflow = Exceptions.OverflowError; TypeCode tc = Type.GetTypeCode(obType); result = null; IntPtr op; int ival; switch(tc) { case TypeCode.String: string st = Runtime.GetManagedString(value); if (st == null) { goto type_error; } result = st; return true; case TypeCode.Int32: // Trickery to support 64-bit platforms. if (IntPtr.Size == 4) { //------ FIX START // convert it to an python int64 op = Runtime.PyNumber_Long(value); // if the conversion fails if (op == IntPtr.Zero) { if (Exceptions.ExceptionMatches(overflow)) { goto overflow; } goto type_error; } // convert it to an int64 long lval = (long)Runtime.PyLong_AsLongLong(op); // and try to convert it to an int32 if ((lval < int.MinValue) || (int.MaxValue < lval)) { Runtime.Decref(op); if (Exceptions.ExceptionMatches(overflow)) { goto overflow; } goto type_error; } Runtime.Decref(op); result = unchecked((int)lval); return true; //------ FIX END } else { op = Runtime.PyNumber_Long(value) //======================================================================= I will send a pull request to the github repo . Could you have a look at it? Thanks, Serge ___________________________________________________________ This e-mail may contain confidential and/or privileged information. If you are not the intended recipient (or have received this e-mail in error) please notify the sender immediately and delete this e-mail. Any unauthorised copying, disclosure or distribution of the material in this e-mail is prohibited. Please refer to http://www.bnpparibas.co.uk/en/email-disclaimer/ for additional disclosures.

1 0

DB api module using pythondotnet and System.Data.SqlClient
by John Gill Sept. 22, 2014

Sept. 22, 2014

I just spend a frustrating afternoon trying to connect to SQL Server(s) with pymssql. The issue was I wanted to use windows authentication rather than supply username and password in the code. After getting no joy and lots of googling I realized I can just do: import clr clr.AddReference('System.Data') from System.Data.SqlClient import SqlConnection Sure enough this works a treat. I need to remember how powerful pythondotnet is and make sure I use it more. Meanwhile, I am wondering if anyone has tried to wrap this stuff up to produce a standard DB-API interface to SQL Server using pythondotnet and SqlConnection? If not, anyone else out there interested in this? John This communication and any attachments contain information which is confidential and may also be legally privileged. It is for the exclusive use of the intended recipient(s). If you are not the intended recipient(s) please note that any form of disclosure, distribution, copying, printing or use of this communication or the information in it or in any attachments is strictly prohibited and may be unlawful. If you have received this communication in error, please return it with the title "received in error" to postmaster(a)tokiomillennium.com and then permanently delete the email and any attachments from your system. E-mail communications cannot be guaranteed to be secure or error free, as information could be intercepted, corrupted, amended, lost, destroyed, arrive late or incomplete, or contain viruses. It is the recipient's responsibility to ensure that e-mail transmissions and any attachments are virus free. We do not accept liability for any damages or other consequences caused by information that is intercepted, corrupted, amended, lost, destroyed, arrives late or incomplete or contains viruses. ******************************************

1 0

Running an embedded interpreter
by Serge WEINSTOCK Sept. 1, 2014

Sept. 1, 2014

Hi, I'm trying to use Python3.2 using the Python.Net version found at: https://github.com/renshawbay/pythonnet I'm using the following simple test program: //======================================================================= using System; using System.IO; using Python.Runtime; namespace TestPythonNet { class Program { static void Main(string[] args) { string binDir = Path.GetDirectoryName(System.Reflection.Assembly.GetAssembly(typeof(Program)).Location); string pyHome = @"D:\src\scratch\TestPythonNet\TestPythonNet\PythonRuntime"; PythonEngine.PythonHome = @"D:\src\scratch\TestPythonNet\TestPythonNet\PythonRuntime"; PythonEngine.ProgramName = "PythonRuntime"; Environment.SetEnvironmentVariable("PYTHONPATH", Path.GetFullPath(Path.Combine(pyHome, "DLLs")) + ";" + Path.GetFullPath(Path.Combine(pyHome, "Lib")) + ";" + Path.GetFullPath(Path.Combine(pyHome, "Lib", "site-packages")) + ";" + binDir ); Environment.SetEnvironmentVariable("PYTHONVERBOSE", "1"); PythonEngine.Initialize(); PythonEngine.ImportModule("clr"); using (Py.GIL()) { PythonEngine.RunSimpleString( "import clr; " + "a = clr.AddReference('System'); " + "print(a.Location);" + "from System import Environment;" + "print(Environment.MachineName);"); } } } } //======================================================================= "D:\src\scratch\TestPythonNet\TestPythonNet\PythonRuntime" is a folder where I've copied the DLLs and Lib folder from a python 3.2 x86 distribution. When I run it from Visual Studio it works fine (I guess it may be related to the fact that I'm using python tools for Visual Studio). But when I run it from the console, it fails with the output: //======================================================================= Traceback (most recent call last): File "D:\src\scratch\TestPythonNet\TestPythonNet\PythonRuntime\Lib\site.py", line 481, in execsitecustomize import sitecustomize UnicodeEncodeError: 'mbcs' codec can't encode characters in position 0--1: invalid character Traceback (most recent call last): File "D:\src\scratch\TestPythonNet\TestPythonNet\PythonRuntime\Lib\site.py", line 497, in execusercustomize import usercustomize UnicodeEncodeError: 'mbcs' codec can't encode characters in position 0--1: invalid character C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System\v4.0_4.0.0.0__b77a5c561934e089\System.dll Traceback (most recent call last): File "<string>", line 1, in <module> UnicodeEncodeError: 'mbcs' codec can't encode characters in position 0--1: invalid character //======================================================================= The "print(a.Location);" works but not the "from System import Environment". There are also all these errors about mbcs. Any idea on what I'm doing wrong? Thanks, Serge Weinstock ___________________________________________________________ This e-mail may contain confidential and/or privileged information. If you are not the intended recipient (or have received this e-mail in error) please notify the sender immediately and delete this e-mail. Any unauthorised copying, disclosure or distribution of the material in this e-mail is prohibited. Please refer to http://www.bnpparibas.co.uk/en/email-disclaimer/ for additional disclosures.

2 11