gh-134939: Add a Multiple Interpreters Howto Doc

[ericsnowcurrently]

• Issue: Add the interpreters Module, Implementing PEP 734 #134939

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📚 Documentation preview 📚: https://cpython-previews--136143.org.readthedocs.build/en/136143/howto/multiple-interpreters.html#multiple-interpreters-howto

[neonene]

Some users might need a (foot)note that subinterpreters can sometimes improve the startup by importing nothing.

example

def non_stateless():
    non_stateless

if __name__ == '__main__':
    import threading
    from concurrent import interpreters
    interps = [interpreters.create() for i in range(10)]
    threads = [
        threading.Thread(target=interp.call, args=(non_stateless,))
        for interp in interps
    ]
    for thread in threads:
        thread.start()
    for thread in threads:
        thread.join()

That seems not so beneficial for the InterpreterPoolExecutor case, though.

[ericsnowcurrently]

I've added a note, though further down in the discussion about calling functions.

[neonene]

Off-topic, but would it be possible to add the daemon parameter to the helper method?

[ericsnowcurrently]

I want to keep the helper super simple. If someone wants a daemon thread then they can do it manually without much effort.

[ericsnowcurrently]

Any objections to merging this?

[hugovk]

This line is unused:

Suggested change

current = expected = start = None

[hugovk]

Suggested change

	def write_example(examplesdir, name, text):
	filename = os.path.join(examplesdir, f'example-{name}.py')
	def write_example(examples_dir, name, text):
	filename = os.path.join(examples_dir, f'example-{name}.py')

[hugovk]

Suggested change

	stdout=subprocess.PIPE,
	stderr=subprocess.PIPE,
	capture_output=True,

[hugovk]

Suggested change

	print(f'all succeeded')
	print('all succeeded')

[hugovk]

Let's remove these exclusions and do the fixes?

Suggested change

exclude: ^Doc/howto/multiple-interpreters-run-examples.py

[hugovk]

Suggested change

	Sharing Data
	------------
	Sharing data
	------------

[hugovk]

Suggested change

	Using Queues
	------------
	Using queues
	------------

[hugovk]

Suggested change

	Initializing Globals for a Script
	---------------------------------
	Initializing globals for a script
	---------------------------------

[hugovk]

Suggested change

	Pipes, Sockets, etc.
	--------------------
	Pipes, sockets, and so on
	-------------------------

Avoid Latin abbreviations: https://devguide.python.org/documentation/style-guide/#use-simple-language

[hugovk]

Suggested change

	Tutorial: Miscellaneous
	=======================
	Tutorial: miscellaneous
	=======================