Threading Semaphore and BoundedSemaphore release method implementation improvement

[besi7dollma]

BPO	45311
Nosy	@rhettinger, @pitrou, @serhiy-storchaka, @Fidget-Spinner, @akulakov

^{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 = None
created_at = <Date 2021-09-28.13:32:03.133>
labels = ['type-feature', 'library', '3.11']
title = 'Threading Semaphore and BoundedSemaphore release method implementation improvement'
updated_at = <Date 2021-10-21.08:42:59.621>
user = 'https://bugs.python.org/besi7dollma'

bugs.python.org fields:

activity = <Date 2021-10-21.08:42:59.621>
actor = 'serhiy.storchaka'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2021-09-28.13:32:03.133>
creator = 'besi7dollma'
dependencies = []
files = []
hgrepos = []
issue_num = 45311
keywords = []
message_count = 4.0
messages = ['402779', '404461', '404570', '404571']
nosy_count = 6.0
nosy_names = ['rhettinger', 'pitrou', 'serhiy.storchaka', 'kj', 'andrei.avk', 'besi7dollma']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue45311'
versions = ['Python 3.11']

[besi7dollma]

Hi,
I was looking at the implementation of Semaphore and BoundedSemaphore in threading.py and I saw that notify is called on a loop n times while it supports an n parameter.

cpython/Lib/threading.py

Line 479 in 8497514

for i in range(n):

Unless I am missing something, removing the loop and replacing it with self._cond.notify(n) will slightly improve performance by avoiding the function call overhead.

I can prepare a Pool Request if the change is acceptable.
Thanks,

[akulakov]

Besart: with the current code, if there's a valueError when releasing a thread, it will be retried again n times, with your change, n waiting threads will be released, even if some of them fail with ValueError.

I don't know enough about threading module to say if this change should be made.

[besi7dollma]

This is another illogical behaviour, if I am trying to release 5 threads, and I fail the releasing the first one, why should I try the first one 5 times?

[serhiy-storchaka]

This code was added in bpo-10978. Raymond, what are your thoughts?