Remove asyncore, asynchat and smtpd modules

[Mariatta]

BPO	28533
Nosy	@warsaw, @orsenthil, @vstinner, @asvetlov, @1st1, @grzgrzgrz3, @Mariatta, @nanjekyejoannah, @aeros, @jacksonriley, @OhSoDank, @iritkatriel
PRs	bpo-28533: Remove asyncore, asynchat, smtpd modules #29521 Revert "bpo-28533: Remove asyncore, asynchat, smtpd modules (GH-29521)" #29951

^{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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assignee = None
closed_at = None
created_at = <Date 2016-10-25.18:32:04.420>
labels = ['3.11', 'tests', 'expert-asyncio']
title = 'Remove asyncore, asynchat and smtpd modules'
updated_at = <Date 2022-02-24.13:39:30.092>
user = 'https://github.com/Mariatta'

bugs.python.org fields:

activity = <Date 2022-02-24.13:39:30.092>
actor = 'vstinner'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Tests', 'asyncio']
creation = <Date 2016-10-25.18:32:04.420>
creator = 'Mariatta'
dependencies = []
files = []
hgrepos = []
issue_num = 28533
keywords = ['patch']
message_count = 37.0
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pr_nums = ['29521', '29951']
priority = 'normal'
resolution = None
stage = 'resolved'
status = 'open'
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url = 'https://bugs.python.org/issue28533'
versions = ['Python 3.11']

• PR: gh-72719: Remove deprecated asyncore and asynchat modules #96580

[Mariatta]

Deprecation warning was added to asyncore in https://bugs.python.org/issue25002

asyncore is still used in several tests and should be replaced.

[vstinner]

asyncore is still used in several tests and should be replaced.

Here is the list of Python files using asyncore:

haypo@selma$ grep -l asyncore $(find -name "*.py")
./Lib/asyncore.py
./Lib/asynchat.py
./Lib/test/test_smtpd.py
./Lib/test/test_asyncore.py
./Lib/test/test_smtplib.py
./Lib/test/test_os.py
./Lib/test/test_ssl.py
./Lib/test/test_logging.py
./Lib/test/libregrtest/save_env.py
./Lib/test/test_asynchat.py
./Lib/test/test_pyclbr.py
./Lib/test/test_support.py
./Lib/test/test_poplib.py
./Lib/test/test_ftplib.py
./Lib/smtpd.py

smtpd has been rewritten with asyncio:
http://aiosmtpd.readthedocs.io/

The documentation of the smtpd module already points to aiosmtpd.

libregrtest/save_env.py only checks that asyncore.socket_map is not modified, we can keep it until asyncore is really removed.

test_support.py only tests that it's possible to have a "clean" import of asyncore, it can be easily be replaced later.

The list can reduced to:

./Lib/test/test_smtplib.py
./Lib/test/test_os.py
./Lib/test/test_ssl.py
./Lib/test/test_logging.py
./Lib/test/test_pyclbr.py
./Lib/test/test_poplib.py
./Lib/test/test_ftplib.py

[vstinner]

asyncore was modified to emit a DeprecationWarning:
http://bugs.python.org/issue25002#msg279417

But then a lot of code starts with to fail -Werror.

Copy of Martin Panter's msg279469:

I normally run the tests with -Werror, and the failures I get are:

• test_ssl, test_smtplib, test_poplib, test_logging, test_ftplib, test_support: tests use asyncore
• test_os: test uses asynchat (When you import asynchat, the first error complains about importing asyncore, there are actually two warnings)
• test_all: This seems to ignore DeprecationWarning; perhaps an exception for PendingDeprecationWarning should also be added?
• test_asyncore and test_asynchat: Obviously these have to still test the modules, so they should anticipate the warnings, perhaps using Serhiy’s code
• test_smtpd: smtpd module itself uses asyncore; see bpo-25008

[grzgrzgrz3]

I would like to work on this issue.

I think it's a good idea to split this task into few parts/PR.

Let me start from ./Lib/test/test_poplib.py.

What about rewriting pop3 server stub using asyncio, i think requests could be handled synchronously, there will be no benefits from asynchronous.

Please let me know what you think.

[vstinner]

I think it's a good idea to split this task into few parts/PR. Let me start from ./Lib/test/test_poplib.py.

Once you have a patch, open a new issue and mention it here.

[grzgrzgrz3]

./Lib/test/test_poplib.py
sub-issue bpo-28533

[grzgrzgrz3]

./Lib/test/test_poplib.py
sub-issue bpo-30514

Fixed issue number from previous comment

[OhSoDank]

Hi, is this still open?

I'm happy to work on replacing asyncore usage in one of the other test files.

[nanjekyejoannah]

@dankreso, the issue is still open and no one has claimed it yet. So feel free to open a pull request.

[aeros]

I'm happy to work on replacing asyncore usage in one of the other test files.

Sounds good, just let us know which one(s) you're working on. (:

[jacksonriley]

Lib/test/test_pyclbr.py - subissue bpo-38866
A trivial one!

[aeros]

Since this issue is now a significant blocker for PEP-594 (remove stdlib dead batteries, which includes asyncore and asynchat), I'm going to prioritize working on this and assign it to myself.