test_weakref super slow on RPi Zero

[DNSGeek]

BPO	36369
Nosy	@vstinner, @mcepl, @DNSGeek, @iritkatriel

^{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 2022-01-15.20:00:58.872>
created_at = <Date 2019-03-19.17:17:17.050>
labels = ['3.7', 'tests']
title = 'test_weakref super slow on RPi Zero'
updated_at = <Date 2022-01-15.20:00:58.871>
user = 'https://github.com/DNSGeek'

bugs.python.org fields:

activity = <Date 2022-01-15.20:00:58.871>
actor = 'iritkatriel'
assignee = 'none'
closed = True
closed_date = <Date 2022-01-15.20:00:58.872>
closer = 'iritkatriel'
components = ['Tests']
creation = <Date 2019-03-19.17:17:17.050>
creator = 'DNSGeek'
dependencies = []
files = []
hgrepos = []
issue_num = 36369
keywords = []
message_count = 3.0
messages = ['338390', '351672', '410661']
nosy_count = 4.0
nosy_names = ['vstinner', 'mcepl', 'DNSGeek', 'iritkatriel']
pr_nums = []
priority = 'normal'
resolution = 'out of date'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue36369'
versions = ['Python 3.7']

[DNSGeek]

When building Python 3.7.2 on a Raspberry Pi Zero W, it takes over 6 hours to run test_weakref, and almost 15 hours total to run through all the tests.

14:28:14 load avg: 1.00 [396/416] test_weakset -- test_weakref passed in 6 hour 24 min

Does it really need to take this long for one test?

[vstinner]

How long take other tests on Raspberry Pi Zero W?

You can try:

./python -m test -j0 --slowest

-j0 spawns one job per CPU. I don't know how many CPUs have this hardware.

--slowest gives the timing of the 10 slowest tests.

But even without --slowest, Python displays the test duration if a test takes longer than 30 seconds.

[iritkatriel]

3.7 is no longer maintained. Please create a new issue if you are seeing slow tests with a current version of python (ideally 3.10 or one of the 3.11 alphas), and you are interested in investigating along the lines of Victor's suggestion.