datetime.strptime becomes None after first run in WASM environment

[treyhunner]

Bug report

The following code runs correctly the first time but then complains that datetime.strptime is of type NoneType the second time the code is run within the same browser session.

"""Demonstrates WASM issue with datetime.strptime."""
from datetime import datetime

print(datetime.strptime("2023-01-13", "%Y-%m-%d"))
print(datetime.strptime("2023-01-13", "%Y-%m-%d"))

Live example here: https://pym.dev/p/2g6wn/

Note that running datetime.strptime twice doesn't cause an issue. The issue seems to be due to exiting Python and then re-entering it. For example in an interactive session, one would need to call exit() and then start the interactive session again in the same browser window (example here).

>>> from datetime import datetime
>>> datetime.strptime("2023", "%Y")
datetime.datetime(2023, 1, 1, 0, 0)
>>> exit()  # The REPL is automatically re-entered after this
>>> from datetime import datetime
>>> datetime.strptime("2023", "%Y")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'NoneType' object is not callable

Your environment

CPython 3.11.0 compiled to Emscripten for the browser.

[brettcannon]

How are you re-initializing the Python runtime between sessions?

[treyhunner]

To re-initialize I'm posting a run message to the web worker, which calls callMain(event.data.args) again.

[abalkin]

This looks like another manifestation of the issue reported at GH-71587.

[brettcannon]

I think @abalkin is right as to the cause, so I'm closing this as a duplicate.