Issue 22696: Add a function to know about interpreter shutdown

I propose to add a new function sys.shutting_down() (name debatable) returning True if the interpreter is currently shutting down.

This would be a function so that you can bind it and avoid having it wiped at shutdown :-)

For the issue #22599, I wrote a patch but then I removed my patch and reverted my changed...

Here is a new patch which implements why I already wrote: add a new sys._is_finalizing() function, with a unit test.

> I propose to add a new function sys.shutting_down() (name debatable)

The name sounds like a function to shut down the computer or exit Python.

I don't like _is_finalizing() name neither :-)

My patch uses a private function which is CPython specific. Does it make sense to add a public function instead? Is it possible to implement it in any Python implementation (PyPy, IronPython, Jython, etC.)? I guess that the most dummy implementation is to always return False (Python is always running.

Are there other special interpreter states about which it would by helpful to 
know? Interpreter initializing, garbage collecting, signal handling?

> My patch uses a private function which is CPython specific.
> Does it make sense to add a public function instead?

I would like it to be public. It can be useful in __del__ methods and the like.

> Are there other special interpreter states about which it would by 
> helpful to know? Interpreter initializing, garbage collecting, signal 
> handling?

- interpreter initializing: user code generally isn't executed in that phase
- garbage collecting: there are already garbage collection callbacks
- signal handling: well... I don't see why that would be useful

I'm +0 for is_finalizing.

There is a typo in the docstring.

An indirect way how to know about interpreter shutdown -- test existing of the path attribute in sys (issue20603).

After solving this issue we should reconsider the traceback_ignore_linecache_error.patch patch in issue22599.

> After solving this issue we should reconsider the traceback_ignore_linecache_error.patch patch in issue22599.

I reposted the patch in this issue since I just closed the issue #22599.

Here is a patch with docs.

is_finalizing2.patch looks good to me.

Before committing the patch it will be good to find places in the code which will benefit from this function.

And please don't forget to fix a typo in the docstring.

> Before committing the patch it will be good to find places in the code which will benefit from this function.

The traceback and/or the linecache is a first good candidate to use this new function. We may patch more functions later if needed, I don't think that we need to address all issues right now.

New changeset 7f3695701724 by Antoine Pitrou in branch 'default':
Issue #22696: Add function :func:`sys.is_finalizing` to know about interpreter shutdown.
https://hg.python.org/cpython/rev/7f3695701724

Using the function in the stdlib can be done separately. I fixed the typo in the docstring. Thanks!

> Using the function in the stdlib can be done separately.

Is there an open issue for that?

stage: needs patch -> resolved

messages: + msg232200

messages: + msg232186