gh-102024: Reduced _idle_semaphore.release calls by jackcvr · Pull Request #102025 · python/cpython · GitHub

_idle_semaphore.release() is called if only work_queue is empty

Benchmarks:
submit_only:

./python -m timeit -n 100000 -r 10 -s 'W = 1; from concurrent.futures import ThreadPoolExecutor; tpe = ThreadPoolExecutor(W)' 'tpe.submit(lambda: None)'

before:
W=1: 100000 loops, best of 10: 17.6 usec per loop
W=2: 100000 loops, best of 10: 10.5 usec per loop
W=4: 100000 loops, best of 10: 10.5 usec per loop
after:
W=1: 100000 loops, best of 10: 7.42 usec per loop
W=2: 100000 loops, best of 10: 7.5 usec per loop
W=4: 100000 loops, best of 10: 7.5 usec per loop

submit_then_wait:

./python -m timeit -n 10 -r 10 -s 'W = 1; from concurrent.futures import ThreadPoolExecutor, wait; tpe = ThreadPoolExecutor(W)' 'fs=[tpe.submit(lambda: None) for _ in range(10_000)]; wait(fs)'

before:
W=1: 10 loops, best of 10: 110 msec per loop
W=2: 10 loops, best of 10: 100 msec per loop
W=4: 10 loops, best of 10: 114 msec per loop
after:
W=1: 10 loops, best of 10: 85.2 msec per loop
W=2: 10 loops, best of 10: 83.9 msec per loop
W=4: 10 loops, best of 10: 86.5 msec per loop

Issue: Reduce _idle_semaphore calls in ThreadPoolExecutor #102024

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Thanks! One more important thing is missing: benchmarks.
Can you please provide some small code sample that will show us that your solution is actually faster now?

@sobolevn BTW is there any newcomer tutorial (edit: how-to) dedicated to pyperf one-liners? https://pyperf.readthedocs.io/en/latest/index.html seems to not serve this purpose.

Added some benchmarks. In my tests there is noticeable boost for submits to one thread.

@arhadthedev I don't know :(
I never needed one, since I've used pyperf before and quite a lot.

_idle_semaphore.release() is called if only work_queue is empty

Thanks, this looks good to me. I have this exact same change in some custom thread pool code I use :-)

I'm a little confused by your benchmarking. I'm not sure why you'd expect the only submit case to speed up (and I can't repro a speed up on that case locally), without shutting down the executor. Of course, if you add the shutdown, I can measure a win (though ofc the size of win varies based on task count, task size, thread count).

…res/thread.py Co-authored-by: Shantanu <12621235+hauntsaninja@users.noreply.github.com>

…utor

🤖 New build scheduled with the buildbot fleet by @hauntsaninja for commit afbdad6 🤖

If you want to schedule another build, you need to add the 🔨 test-with-buildbots label again.

Thanks @jackcvr for the PR, and @gpshead for merging it 🌮🎉.. I'm working now to backport this PR to: 3.12.
🐍🍒⛏🤖

Reduced _idle_semaphore.release calls in concurrent.futures.thread._worker _idle_semaphore.release() is now only called if only work_queue is empty. --------- (cherry picked from commit 0242e9a) Co-authored-by: Andrii Kuzmin <jack.cvr@gmail.com> Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com> Co-authored-by: Shantanu <12621235+hauntsaninja@users.noreply.github.com>

GH-104959 is a backport of this pull request to the 3.12 branch.

…104959) gh-102024: Reduced _idle_semaphore.release calls (GH-102025) Reduced _idle_semaphore.release calls in concurrent.futures.thread._worker _idle_semaphore.release() is now only called if only work_queue is empty. --------- (cherry picked from commit 0242e9a) Co-authored-by: Andrii Kuzmin <jack.cvr@gmail.com> Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com> Co-authored-by: Shantanu <12621235+hauntsaninja@users.noreply.github.com>

bedevere-bot added the awaiting review label Feb 18, 2023

bedevere-bot mentioned this pull request Feb 18, 2023

Reduce _idle_semaphore calls in ThreadPoolExecutor #102024

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arhadthedev added the stdlib Standard Library Python modules in the Lib/ directory label Feb 18, 2023

sobolevn reviewed Feb 18, 2023

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Comment thread Lib/concurrent/futures/thread.py Outdated

jackcvr and others added 2 commits February 19, 2023 23:20

gh-102024 : Reduced _idle_semaphore.release calls

56949ea

_idle_semaphore.release() is called if only work_queue is empty

📜🤖 Added by blurb_it.

09e1c79

hauntsaninja approved these changes Feb 20, 2023

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Comment thread Lib/concurrent/futures/thread.py Outdated

bedevere-bot added awaiting merge and removed awaiting review labels Feb 20, 2023

jackcvr and others added 3 commits February 20, 2023 12:22

Changed issue reference issue16284 -> GH-60488 in Lib/concurrent/futu…

0f50fe5

…res/thread.py Co-authored-by: Shantanu <12621235+hauntsaninja@users.noreply.github.com>

Merge branch 'main' into optimized-idle-semaphore-in-thread-pool-exec…

b071747

…utor

Merge branch 'main' into optimized-idle-semaphore-in-thread-pool-exec…

afbdad6

…utor

hauntsaninja requested a review from gpshead May 1, 2023 00:05

hauntsaninja added the 🔨 test-with-buildbots Test PR w/ buildbots; report in status section label May 24, 2023

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gpshead approved these changes May 26, 2023

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gpshead added the needs backport to 3.12 only security fixes label May 26, 2023

gpshead merged commit 0242e9a into python:main May 26, 2023

bedevere-bot removed the awaiting merge label May 26, 2023

bedevere-bot removed the needs backport to 3.12 only security fixes label May 26, 2023

erlend-aasland mentioned this pull request Jun 6, 2023

3.12 backport gh 105236 #105358

Closed

gh-102024: Reduced _idle_semaphore.release calls by jackcvr · Pull Request #102025 · python/cpython · GitHub

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gh-102024: Reduced _idle_semaphore.release calls - #102025

gh-102024: Reduced _idle_semaphore.release calls#102025gpshead merged 5 commits intopython:mainpython/cpython:mainfrom jackcvr:optimized-idle-semaphore-in-thread-pool-executorCopy head branch name to clipboard

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gh-102024: Reduced _idle_semaphore.release calls#102025
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