gh-97696: asyncio eager tasks factory #102853

itamaro · 2023-03-20T22:13:58Z

pyperformance results:

async tree benchmarks up to ~50% faster when using the eager tasks factory (depending on how many leaf nodes actually suspend)
geometric mean for all benchmark 1% faster

pyperformance run performed with local patch that installs the eager tasks factory by default (modifying the benchmark itself to use it requires psf/pyperf#157)

full comparison in this gist

Doc/library/asyncio-task.rst

itamaro · 2023-03-21T03:36:57Z

I'm still chasing a refleak, but otherwise this should be ready for review

Doc/library/asyncio-task.rst

gvanrossum · 2023-03-22T17:59:52Z

It looks like @graingert's observation is a serious problem. How can we fix this?

Always create a task object to resolve the design flaw with structured concurrency. Push the eager step execution into the task implementation, so the task itself knows to eagerly execute the first step if created via the eager task factory. Co-authored-by: Jacob Bower <[email protected]>

Co-authored-by: Jacob Bower <[email protected]>

itamaro · 2023-04-21T22:48:06Z

latest version of this PR resolves the issues raised on the issue. tests pass, and rerunning the benchmarks results in pretty much the same results (differences from the original impl within noise margins).

benchmarks ran using pyperformance with this patch.

willingc · 2023-05-01T12:36:44Z

@gvanrossum @carljm Could you please take a quick look at this and make sure it resolved your comments? If so, we can merge. Thanks!

gvanrossum

LGTM (assuming the refcount leak buildbots are happy). Go ahead without waiting for me with further changes!

PS. Next time please resist the urge to rebase -- it's harder to pick up a review after a rebase has happened. We squash commits when we merge them into main anyways.

carljm

LGTM barring a couple doc nits and one question.

Doc/library/asyncio-task.rst

Lib/asyncio/tasks.py

Misc/NEWS.d/next/Library/2023-03-15-12-18-07.gh-issue-97696.DtnpIC.rst

Lib/asyncio/tasks.py

bedevere-bot · 2023-05-01T18:20:44Z

🤖 New build scheduled with the buildbot fleet by @carljm for commit b17f605 🤖

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

* main: (463 commits) pythongh-104057: Fix direct invocation of test_super (python#104064) pythongh-87092: Expose assembler to unit tests (python#103988) pythongh-97696: asyncio eager tasks factory (python#102853) pythongh-84436: Immortalize in _PyStructSequence_InitBuiltinWithFlags() (pythongh-104054) pythongh-104057: Fix direct invocation of test_module (pythonGH-104059) pythongh-100458: Clarify Enum.__format__() change of mixed-in types in the whatsnew/3.11.rst (pythonGH-100387) pythongh-104018: disallow "z" format specifier in %-format of byte strings (pythonGH-104033) pythongh-104016: Fixed off by 1 error in f string tokenizer (python#104047) pythonGH-103629: Update Unpack's repr in compliance with PEP 692 (python#104048) pythongh-102799: replace sys.exc_info by sys.exception in inspect and traceback modules (python#104032) Fix typo in "expected" word in few source files (python#104034) pythongh-103824: fix use-after-free error in Parser/tokenizer.c (python#103993) pythongh-104035: Do not ignore user-defined `__{get,set}state__` in slotted frozen dataclasses (python#104041) pythongh-104028: Reduce object creation while calling callback function from gc (pythongh-104030) pythongh-104036: Fix direct invocation of test_typing (python#104037) pythongh-102213: Optimize the performance of `__getattr__` (pythonGH-103761) pythongh-103895: Improve how invalid `Exception.__notes__` are displayed (python#103897) Adjust expression from `==` to `!=` in alignment with the meaning of the paragraph. (pythonGH-104021) pythongh-88496: Fix IDLE test hang on macOS (python#104025) Improve int test coverage (python#104024) ...

* main: (760 commits) pythonGH-104102: Optimize `pathlib.Path.glob()` handling of `../` pattern segments (pythonGH-104103) pythonGH-104104: Optimize `pathlib.Path.glob()` by avoiding repeated calls to `os.path.normcase()` (pythonGH-104105) pythongh-103822: [Calendar] change return value to enum for day and month APIs (pythonGH-103827) pythongh-65022: Fix description of tuple return value in copyreg (python#103892) pythonGH-103525: Improve exception message from `pathlib.PurePath()` (pythonGH-103526) pythongh-84436: Add integration C API tests for immortal objects (pythongh-103962) pythongh-103743: Add PyUnstable_Object_GC_NewWithExtraData (pythonGH-103744) pythongh-102997: Update Windows installer to SQLite 3.41.2. (python#102999) pythonGH-103484: Fix redirected permanently URLs (python#104001) Improve assert_type phrasing (python#104081) pythongh-102997: Update macOS installer to SQLite 3.41.2. (pythonGH-102998) pythonGH-103472: close response in HTTPConnection._tunnel (python#103473) pythongh-88496: IDLE - fix another test on macOS (python#104075) pythongh-94673: Hide Objects in PyTypeObject Behind Accessors (pythongh-104074) pythongh-94673: Properly Initialize and Finalize Static Builtin Types for Each Interpreter (pythongh-104072) pythongh-104016: Skip test for deeply neste f-strings on wasi (python#104071) pythongh-104057: Fix direct invocation of test_super (python#104064) pythongh-87092: Expose assembler to unit tests (python#103988) pythongh-97696: asyncio eager tasks factory (python#102853) pythongh-84436: Immortalize in _PyStructSequence_InitBuiltinWithFlags() (pythongh-104054) ...

kumaraditya303 · 2023-05-05T04:31:12Z

Modules/_asynciomodule.c

+        }
+    } else {
+        // This seems to really help performance on pyperformance benchmarks
+        Py_CLEAR(task->task_coro);


Is this documented anywhere? I can't find it

See my comments on #97696.

Also #104304 as possible documentation.

Lib/asyncio/tasks.py

Modules/_asynciomodule.c

…ing check based on feedback from python#102853 (review)

willingc · 2023-05-09T05:59:55Z

Great to see this land @itamaro. Thanks for being so collaborative on working through the PR. 🎉

Dreamsorcerer · 2024-08-08T12:15:50Z

The proposal at the start of this thread suggested a new method or parameter for eager start. Is there a link to any discussion on why this changed? Are there plans to do something like that in future (or just to make it the default, and remove the old behaviour)?

I'm thinking about this from a library side. Changing the global task factory is inappropriate for a library to do, but we still have certain tasks that would strongly benefit from eager execution (I also wonder if a user enabling this globally could end up breaking a library that wasn't expecting eager tasks...).

So, some way to execute individual tasks eagerly would be useful (unless it simply becomes the default behaviour). We currently instantiate Task(eager_start=True) directly, though the docs seem to strongly discourage this. Adding an eager_start to asyncio.create_task(), or maybe some way to temporarily change task factories (with eager_task_factory:) would be ideal.

bedevere-bot mentioned this pull request Mar 20, 2023

Add eager task creation API to asyncio #97696

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itamaro force-pushed the eager-tasks-factory branch from 2a961d3 to 245a52b Compare March 20, 2023 22:21

carljm reviewed Mar 20, 2023

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itamaro force-pushed the eager-tasks-factory branch from 245a52b to bcf40dc Compare March 20, 2023 23:04

AlexWaygood added the topic-asyncio label Mar 21, 2023

itamaro marked this pull request as ready for review March 21, 2023 03:37

itamaro requested review from 1st1, asvetlov, gvanrossum and kumaraditya303 as code owners March 21, 2023 03:37

gvanrossum reviewed Mar 21, 2023

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itamaro and others added 8 commits April 20, 2023 13:42

Eager task factory implementation

a127f98

Eager task factory tests

45316d8

Add NEWS and docs for eager task factory

ac9b7b0

elaborate explanation in docs and add a whatsnew entry

402c317

fix docs

563ffd4

Fix task-counting tests for new impl

e7743f6

Fix test_task_exc_handler_correct_context

10a03a0

Co-authored-by: Jacob Bower <[email protected]>

itamaro force-pushed the eager-tasks-factory branch from 29d04c2 to 10a03a0 Compare April 21, 2023 03:10

Merge branch 'main' into eager-tasks-factory

5e8ae51

itamaro mentioned this pull request Apr 21, 2023

Extend async tree benchmarks to cover eager task execution python/pyperformance#279

Merged

itamaro added 4 commits April 24, 2023 17:41

Merge branch 'main' into eager-tasks-factory

b4fea1c

add jbower credit

441fd92

cleanup recursive_taskgroups test case

4c46a72

Merge branch 'main' into eager-tasks-factory

8686a3d

gvanrossum approved these changes May 1, 2023

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carljm reviewed May 1, 2023

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itamaro added 5 commits May 1, 2023 09:59

missing word in NEWS entry

0c09767

refactor all_tasks() handling of eager_tasks

a255ec8

fix docs (PR review)

05870d5

move cv.set inside the main task (otherwise it refleaks)

a2587a1

Merge branch 'main' into eager-tasks-factory

0101742

carljm reviewed May 1, 2023

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itamaro added 2 commits May 1, 2023 11:14

fix grammar in all_tasks comments

b83ed94

Merge branch 'main' into eager-tasks-factory

b17f605

carljm added the 🔨 test-with-refleak-buildbots Test PR w/ refleak buildbots; report in status section label May 1, 2023

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carljm merged commit a474e04 into python:main May 1, 2023

bedevere-bot removed the awaiting merge label May 1, 2023

JelleZijlstra mentioned this pull request May 1, 2023

Cannot run tests #104070

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kumaraditya303 reviewed May 5, 2023

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jbower-fb mentioned this pull request May 5, 2023

gh-97696 Remove unnecessary check for eager_start kwarg #104188

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jbower-fb mentioned this pull request May 5, 2023

gh-97696: Remove redundant #include #104216

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itamaro added a commit to itamaro/cpython that referenced this pull request May 7, 2023

pythongh-97696: Use PyObject_CallMethodNoArgs and inline is_loop_runn…

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…ing check based on feedback from python#102853 (review)

itamaro mentioned this pull request May 7, 2023

gh-97696: Use PyObject_CallMethodNoArgs and inline is_loop_running check #104255

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itamaro deleted the eager-tasks-factory branch May 7, 2023 22:16

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gh-97696: asyncio eager tasks factory #102853

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