"threading._DummyThread" redefines "is_alive" but forgets "isAlive"

[d-maurer]

BPO	35283
Nosy	@brettcannon, @d-maurer, @vstinner, @asvetlov, @pmp-p, @serhiy-storchaka, @corona10
PRs	bpo-35283: Add a deprecated warning for the threading.Thread.isAlive #11454 bpo-35283: Add a deprecated warning for the threading.Thread.isAlive #11454 bpo-35283: Add a deprecated warning for the threading.Thread.isAlive #11454 [3.7] bpo-35283: Add a deprecated warning for the threading.Thread.isAlive #11459 [3.7] bpo-35283: Add a deprecated warning for the threading.Thread.isAlive #11459 [3.7] bpo-35283: Add a deprecated warning for the threading.Thread.isAlive #11459 bpo-35283: Update the docstring of threading.Thread.join method #11596 bpo-35283: Update the docstring of threading.Thread.join method #11596 bpo-35283: Update the docstring of threading.Thread.join method #11596 [3.7] bpo-35283: Add deprecation warning for Thread.isAlive (GH-11454) #11604 [3.7] bpo-35283: Add deprecation warning for Thread.isAlive (GH-11454) #11604 [3.7] bpo-35283: Add deprecation warning for Thread.isAlive (GH-11454) #11604

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2019-01-18.14:17:47.552>
created_at = <Date 2018-11-20.22:16:29.238>
labels = ['3.7', '3.8', 'type-bug', 'library']
title = '"threading._DummyThread" redefines "is_alive" but forgets "isAlive"'
updated_at = <Date 2019-01-18.14:17:47.547>
user = 'https://github.com/d-maurer'

bugs.python.org fields:

activity = <Date 2019-01-18.14:17:47.547>
actor = 'asvetlov'
assignee = 'none'
closed = True
closed_date = <Date 2019-01-18.14:17:47.552>
closer = 'asvetlov'
components = ['Library (Lib)']
creation = <Date 2018-11-20.22:16:29.238>
creator = 'dmaurer'
dependencies = []
files = []
hgrepos = []
issue_num = 35283
keywords = ['patch']
message_count = 27.0
messages = ['330158', '330216', '330219', '330237', '330242', '330244', '330245', '330247', '330248', '330277', '330278', '330279', '330280', '330293', '330472', '330917', '330922', '333156', '333170', '333854', '333856', '333911', '333930', '333951', '333954', '333955', '333966']
nosy_count = 7.0
nosy_names = ['brett.cannon', 'dmaurer', 'vstinner', 'asvetlov', 'pmpp', 'serhiy.storchaka', 'corona10']
pr_nums = ['11454', '11454', '11454', '11459', '11459', '11459', '11596', '11596', '11596', '11604', '11604', '11604']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue35283'
versions = ['Python 3.7', 'Python 3.8']

[d-maurer]

In module "threading", class "Thread" defines "is_alive" and defines "isAlive = is_alive". The derived class "_DummyThread" redefines "is_alive" but forgets to update the "isAlive" alias. As a consequence, calling "_DummyThread.isAlive" leads to an "AssertionErrror".

The "isAlive" method is mentioned in the docstring of "Thread.join".

[brettcannon]

Care to open a PR to fix this?

[d-maurer]

Care to open a PR to fix this?

I am not familiar with the "github" workflow. The fix is so trivial (add the "isAlive = is_alive" alias to "threading._DummyThread" and replace "isAlive" by "is_alive" in the docstring of "threading.Thread.join" that it does not seem worth to learn the "github" workflow just for this fix.

[corona10]

Hi, Can I work with this issue if no one works on it?

[serhiy-storchaka]

isAlive() is the part of the old API. It is not even documented in Python 3, and can be removed in future. It is better to remove it from docstrings.

[serhiy-storchaka]

And since threads support no longer optional, are there reasons to keep _DummyThread?

[pitrou]

If it's not already deprecated, I'd say deprecate it first.

[corona10]

@serhiy.storchaka @pitrou
Then should we add the deprecated message
for isAlive of class "Thread" first?

[asvetlov]

The only _DummyThread usage is threading.current_thread():

If the caller's thread of control was not created through the threading
module, a dummy thread object with limited functionality is returned.

[brettcannon]

I guess the question is whether any other Python implementation is threadless? E.g. is MicroPython? If it even has threads then I agree about deprecating the module.

But if MicroPython does support threads we should keep the module. That would mean updating all references of isAlive() to is_alive() and adding the name alias since that name aliasing still exists in 'master' right now (probably for Python 2 porting support):

cpython/Lib/threading.py

Line 1094 in 3bb183d

isAlive = is_alive

@dmaurer totally understand about time restraints, but do realize even "trivial" fixes like this would still take at least an hour to do a proper job so there's no guarantee someone will get around to fixing this. But if you do change your mind and want to give it a try, then https://devguide.python.org/ is there to help.

[pmp-p]

I guess the question is whether any other Python implementation is threadless?

emscripten python ( cpython on asm.js or webassembly ) is threadless