Mailman 3 May 2020 - 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

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Working group notes for Feb 27, 2020
by Mark Visser May 21, 2020

May 21, 2020

Attendees: Victor, Mark, Benedikt, Benoit, Amos, Felix Agenda Review action items from last meeting: Benoit to finish wiki page for threading Victor will talk to Benedikt regarding creating a lib/separate repo for codecs (this also applies to QuantConnect) Quantconnect PR - Victor to ensure Amos commits are mirrored in master Amos should take over PR #1016 Victor will try to review #958 instead See if Benedikt needs better time or we can make decisions while he’s off Unity is settled on 2.4.0, and might reduce presence Create NuGet organization and transfer package ownership for NuGet package <https://www.nuget.org/packages/pythonnet/> At least 1 more person to admin NuGet org Mailing list for maintainers only A plan to replace IntPtr with the new reference types Upstreaming Lost Tech (Victor’s) fork Python 2 support? DllImport -> GetDelegateForFunctionPointer Notes Wiki page for threading is up in tutorials section Victor & Amos discussing failing multithreading test case in PR #1022 Looks like Amos's commits in the Quantconnect PR are already in master PR #1016 closed in favour of using PR #958 instead Slow going on PR #958 review needs some description to explain the changes - a few sentences that describe the intended effects of the changes: what actions are necessary to implement soft shutdown? hard to get overall picture of what the code is expected to do Regarding the time slot this is the best we can get that balances China, North America and Germany time zones it's OK for Victor make decisions in the meeting - unless Benedikt is completely against the decision, it will be OK NuGet org Victor has access problem is that registered e-mail is the mailing list e-mail, security hole A plan to replace IntPtr with the new reference types we should avoid using IntPtr in our own pull requests should use proper pointer types ourselves, once we've got good practices established can be documented belongs with Benedikt's work on loader PR Upstreaming Lost Tech (Victor’s) fork Python 2 support not handled, should we drop support from master (and move 2.x to branch)? DllImport -> GetDelegateForFunctionPointer change require dropping 2.x in general dropping 2.x helps with a lot of things not a problem for Unity, also moving to 3.x No arguments against dropping support for 2.x in master were raised is master in a good state for a last release of 2.x? have one last push to get any changes not specific to 3.x into master before branch-off / tag codecs other minor changes stability of current release? random CI failures we added more tests recently - e.g. domain reload tests unstable one of the domain reload tests often fails on Python 2.7 Amos' changes for normal mode shutdown should solve these failures - should we land them first? no, let's only backport them if there is demand master is currently green As soon as we have all PRs we want in, we will tag 2.4.1 (if no breaking changes, 2.5 otherwise) and branch if necessary will use a github milestone to track PRs for 2.4.1 Still failing tests on 3.8, but likely a dependency on 3.7 - next release should have 3.8 support Lost Tech branch has support for Python version independence (except for 3.8) complete version independence requires dynamic tp slot handling will need runtime logic for handling different versions of Python to handle differing slot locations also need to remove PInvoke usage solving for these two issues will allow any Python version to be used at runtime instead of requiring pre-build for specific versions Lost Tech branch doesn't handle embedding C# in Python, but CLR loader PR should take care of this - already working, and should work with Lost Tech branch changes Dynamic CLR loading won't support 2.4 Action Items Victor will create codecs repo on github Amos to create issue or PR to make implicit operator for reference types to convert reference to IntPtr Amos will create wiki page to explain soft shutdown Benedikt will look into creating a private mailing list for maintainers only Everyone - tag PRs you want to land in 2.4.1, we'll try to get merged before next release Benedikt to check that modernization branch will work with 3.8 The meeting notes google doc is here <https://docs.google.com/document/d/1rJVU84B_dgx58-_EopjRtOJVFAI2WfHJYV0n7uE…>. Feel free to correct or add additional information. The next meeting will be held on Thursday, March 12th at 12pm EST, 9am PST, 6pm CET, 1am China. Mark Visser Tooling Dev Manager Unity Technologies - www.unity3d.com <http://www.unity3d.com/>

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Is it possible to check if a .NET class is a subclass of another .NET class
by robert.hoelzl＠posteo.de May 20, 2020

May 20, 2020

In python I can check the inheritance via isinstance() (and issubclass()). These methods do not work on .NET classes. Are there alternative methods which are doing the job for .NET

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How to run in STA without spawning an extra thread
by robert.hoelzl＠posteo.de May 19, 2020

May 19, 2020

I want to create a WPF app, which requires a STA thread. Unfortunately the main-thread of python.exe runs in MTA and thus cannot be utilitized. I had to spwan an extra thread, But this makes my IDE's (PyCharm) debugger not work any more (does not stop on breakpoints). I downloaded the Python.NET sources to create a version that runs in STA, but I failed to find any piece of code, that activates MTA (and which I could change to STA). I expected it to be in "/src/monoclr/pynetinit.c", but here I only found the code to load Python.Runtime.dll. can anyone give me a hint? regards, Robert

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