'NoneType' object has no attribute 'pydev_notify_kill' on Flask with multiprocess implementation

[lorieaiah]

Environment data

• PTVSD version: 4.2.10
• OS and version: Ubuntu 18.04
• Python version (& distribution if applicable, e.g. Anaconda): Flask 0.12.2 with Python 3.6.8
• Using VS Code or Visual Studio: VS Code (1.36.0)

Actual behavior

in notify_thread_not_alive:
was_notified = thread.additional_info.pydev_notify_kill
'NoneType' object has no attribute 'pydev_notify_kill'

Expected behavior

Should continue

Steps to reproduce:

1. Using multiprocessing.managers class BaseManager

Tried these:

import ptvsd ptvsd.debug_this_thread()
2.
ptvsd.enable_attach(address=('127.0.0.1', 7777), redirect_output=True) ptvsd.wait_for_attach()
Sorry if this is a dumb report

[int19h]

Can you check if your debug configuration in launch.json is using all the necessary command line switches for Flask?

https://code.visualstudio.com/docs/python/debugging#_flask-debugging

[karthiknadig]

@lorieaiah Can you provide details on the OS and python version etc? Also, any sort of repro steps would be helpful as well.

[fabioz]

Inspecting the code I think this could be caused by a race condition. The pull request above should fix it (although as a note, I haven't been able to reproduce locally).

[lorieaiah]

Sorry for incomplete information. l updated the description above.

[int19h]

@lorieaiah, if you're using multiprocessing specifically, then you currently need to do set_start_method("spawn") - otherwise ptvsd cannot debug it on non-Windows platforms. See the comments in #1162 for a more detailed explanation and code snippets.