Drop support for Python 3.8

[notatallshaw]

Python 3.8 support, from the Python Foundation, is ending in a few weeks: https://endoflife.date/python

This is to track ending Python 3.8 support, see 3.7 end: #11934 and #11944

There is motivation as pip will not be able to vendor urllib3 2 until Python 3.9 support is dropped: #12857. Which contains bugfixes/features that will not be backported.

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[ichard26]

Paging @hugovk for the pip downloads stats. My gut reaction is that dropping support for Python 3.8 right after EOL may be a bit too painful.

[hugovk]

From https://hugovk.github.io/pypi-tools/charts.html#pip:

PyPI downloads for the last 30 days, for all versions of pip shows 9.52% with Python 3.8:

❯ pypinfo --all --percent --markdown pip pyversion
Served from cache: False
Data processed: 5.73 GiB
Data billed: 5.73 GiB
Estimated cost: $0.03

python_version	percent	download_count
3.11	24.16%	63,984,763
3.10	18.94%	50,175,163
3.7	17.09%	45,261,471
3.9	13.80%	36,541,609
3.8	9.52%	25,211,245
3.12	6.35%	16,818,377
3.6	3.83%	10,134,044
2.7	3.48%	9,216,031
None	2.64%	7,004,762
3.13	0.20%	524,934
Total		264,872,399

Limiting to only downloads of pip==24, with the reasoning that users of pip==24 are most likely to upgrade to 24.3 and excluding those who never upgrade anyway, shows 1.35% for Python 3.8:

❯ pypinfo --all --percent --markdown pip==24 pyversion
Served from cache: False
Data processed: 7.45 GiB
Data billed: 7.45 GiB
Estimated cost: $0.04

python_version	percent	download_count
3.7	72.42%	29,422,847
3.11	8.86%	3,599,931
None	6.70%	2,721,770
3.9	4.90%	1,991,069
3.10	3.04%	1,237,178
3.12	2.61%	1,059,822
3.8	1.35%	547,122
2.7	0.11%	44,067
3.13	0.01%	4,304
3.6	0.01%	2,723
Total		40,630,833

A 3.7 aside

Python 3.7 has already been dropped, but Amazon Linux is still responsible for all the 3.7 downloads:

❯ pypinfo --limit 20 --percent --markdown pip==24 system distro pyversion
Served from cache: False
Data processed: 13.65 GiB
Data billed: 13.65 GiB
Estimated cost: $0.07

system_name	distro_name	python_version	percent	download_count
Linux	Amazon Linux	3.7	69.89%	24,760,195
Linux	Ubuntu	3.7	7.20%	2,549,869
Linux	Ubuntu	3.9	4.97%	1,759,663
Linux	Ubuntu	3.11	4.53%	1,606,464
Linux	Debian GNU/Linux	3.7	3.96%	1,402,552
Linux	Ubuntu	3.10	2.82%	1,000,292
Linux	Ubuntu	3.12	1.26%	445,796
Windows	None	3.7	0.95%	338,158
Linux	Debian GNU/Linux	3.12	0.95%	335,066
Linux	Ubuntu	3.8	0.87%	306,601
Windows	None	3.12	0.52%	183,841
Linux	Debian GNU/Linux	3.8	0.40%	143,088
Linux	Alpine Linux	3.7	0.31%	108,246
Linux	CentOS Linux	3.7	0.28%	99,851
Linux	Debian GNU/Linux	3.9	0.26%	92,373
Linux	Debian GNU/Linux	3.11	0.22%	76,679
Windows	None	3.10	0.17%	59,970
Linux	Debian GNU/Linux	3.10	0.17%	58,698
Linux	Amazon Linux AMI	3.7	0.14%	50,665
Darwin	macOS	3.7	0.14%	48,986
Total				35,427,053

[notatallshaw]

Limiting to only downloads of pip==24

Does that mean pip versions 24.* or pip version 24.0?

[hugovk]

Hmm, I thought it meant all 24.* but it's more like 24.0. Here's numbers for each minor version:

24.0: 40.7m (last to support 3.7)

python_version	percent	download_count
3.7	72.42%	29,446,324
3.11	8.97%	3,645,590
None	6.67%	2,713,850
3.9	4.84%	1,969,068
3.10	3.03%	1,230,237
3.12	2.60%	1,058,185
3.8	1.34%	545,217
2.7	0.11%	44,393
3.13	0.01%	5,211
3.6	0.01%	2,725
Total		40,660,800

24.1: 0.2m

python_version	percent	download_count
3.12	22.36%	49,503
3.11	16.97%	37,565
3.8	16.16%	35,779
3.10	15.41%	34,106
2.7	14.04%	31,069
3.9	7.25%	16,039
None	7.00%	15,500
3.13	0.66%	1,452
3.14	0.11%	240
3.5	0.05%	105
Total		221,358

24.2: 167.2m

python_version	percent	download_count
3.11	31.56%	52,780,082
3.10	27.36%	45,751,785
3.9	18.69%	31,250,535
3.8	12.22%	20,433,838
3.12	8.57%	14,338,283
None	0.68%	1,131,623
2.7	0.48%	809,263
3.13	0.32%	537,260
3.7	0.10%	174,948
3.6	0.02%	31,955
Total		167,239,572

[ichard26]

I realize that in the case of Python 3.7, we were in favour of dropping support for it promptly, but I really don't see any worthwhile benefits from dropping 3.8 soon. It'd be nice to fix some bugs in the 24 series for 3.8 users, and then we can revisit the question closer to 25.0.

For context, I grepped all of pip's source code for references to Python 3.8 for any code that we could clean up and I only got one hit in the resolvelib glue:

pip/src/pip/_internal/resolution/resolvelib/found_candidates.py

Lines 28 to 39 in 348c428

	else:
	# For compatibility: Python before 3.9 does not support using [] on the
	# Sequence class.
	#
	# >>> from collections.abc import Sequence
	# >>> Sequence[str]
	# Traceback (most recent call last):
	# File "<stdin>", line 1, in <module>
	# TypeError: 'ABCMeta' object is not subscriptable
	#
	# TODO: Remove this block after dropping Python 3.8 support.
	SequenceCandidate = Sequence

Of course, starting in Python 3.9, many built-in types are now subscriptable for typing purposes. Other than that, I'm not aware of anything major we'd be gaining. Python 3.9 is indeed the real kicker as that unblocks the upgrade to urllib3's 2.x series. (And then Python 3.10 as that's the last version to use the old metadata backend.)

[notatallshaw]

24.1: 0.2m

Can you please check for 24.1.2, both 24.0 and 24.2 didn't have patch releases, but 24.1 had two followup patch releases, and I'm guessing by the fact you're seeing 24.1 as 100x less downloads it's because the numbers are only for 24.1 and not 24.1.1 or 24.1.2: https://pypi.org/project/pip/#history

[notatallshaw]

I realize that in the case of Python 3.7, we were in favour of dropping support for it promptly, but I really don't see any worthwhile benefits from dropping 3.8 soon. It'd be nice to fix some bugs in the 24 series for 3.8 users, and then we can revisit the question closer to 25.0.

From my point of view I think the only compelling reason to drop older versions of Python is to support any vendored packages that don't 100% support older versions of Python. And in this case I think the most important example is urllib3 2.0, which pip can not vendor until it drops Python 3.9. And the longer pip waits for Python 3.8 to be dropped the more of a shock it will be to users if Python 3.9 is dropped quickly.

I don't think there is significant technical debt in pip from supporting older 3.x versions, and if it wasn't for pip needing to vendor libraries I would consider it appropriate to support old versions of Python until the CI broke.

[ichard26]

I think a reasonable cutoff is pip 24 is the last series to support Python 3.8. Not particularly meaningful, at least hey we can point "it's a major release, y'all happy semvar folks?!"

I'm only half-joking :)

[hugovk]

24.1: 0.2m

Can you please check for 24.1.2, both 24.0 and 24.2 didn't have patch releases, but 24.1 had two followup patch releases, and I'm guessing by the fact you're seeing 24.1 as 100x less downloads it's because the numbers are only for 24.1 and not 24.1.1 or 24.1.2: pypi.org/project/pip#history

Yep, that sounds about right, 24.1.2 is bigger but still fairly low:

24.1.1: 0.2m

python_version	percent	download_count
3.10	21.79%	48,633
3.12	19.79%	44,168
3.8	17.69%	39,478
3.11	14.72%	32,862
2.7	13.94%	31,119
3.9	5.85%	13,057
None	5.77%	12,871
3.13	0.41%	910
3.5	0.05%	108
3.7	0.00%	3
Total		223,209

24.1.2: 0.5m

python_version	percent	download_count
3.12	18.93%	86,180
3.10	18.45%	83,981
None	16.27%	74,055
3.9	14.67%	66,780
3.8	13.56%	61,759
3.11	10.85%	49,383
2.7	7.00%	31,885
3.13	0.24%	1,106
3.5	0.02%	111
3.14	0.01%	56
Total		455,296

[notatallshaw]

Yep, that sounds about right, 24.1.2 is bigger but still fairly low:

That's fascinating how starkly different orders of magnitude the 24.1 releases are, it really makes me wonder what dominates download numbers and how useful they actually are from a project maintenance perspective.

I think a reasonable cutoff is pip 24 is the last series to support Python 3.8. Not particularly meaningful, at least hey we can point "it's a major release, y'all happy semvar folks?!"

I'm only half-joking :)

I guess we take a look again closer to the 25.0 release? And if there isn't a truststore release and vendor before 24.3, as I mention in #12941 (comment), I think it would be quite helpful to some users to do one more Python 3.8 release with that new version of truststore.