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PEP 703 Deferred reference counts #121459

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Fidget-Spinner opened this issue Jul 7, 2024 · 3 comments
Closed

PEP 703 Deferred reference counts #121459

Fidget-Spinner opened this issue Jul 7, 2024 · 3 comments
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topic-free-threading type-feature A feature request or enhancement

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@Fidget-Spinner
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Fidget-Spinner commented Jul 7, 2024 •
edited by bedevere-app bot
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Feature or enhancement

Proposal:

PEP 703 proposes deferred reference counting to reduce contention between threads on shared objects' reference count fields.

This issue is not in conflict with Faster CPython's scheme of fully removing reference counts in the eval loop. In fact, some of the work runs parallel to it and will actually help it.

There are 3 wins I can observe right now:

  • deferring LOAD_GLOBAL
  • deferring LOAD_ATTR
  • deferring frames' strong references on the code object and function (this is the hardest of the three)

I shall proceed in this order.

Has this already been discussed elsewhere?

No response given

Links to previous discussion of this feature:

No response

Linked PRs
@Fidget-Spinner Fidget-Spinner added type-feature A feature request or enhancement topic-free-threading labels Jul 7, 2024
@bedevere-app bedevere-app bot mentioned this issue Aug 18, 2024
Merged
@markshannon markshannon mentioned this issue Sep 12, 2024
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Fidget-Spinner added a commit that referenced this issue Sep 13, 2024
@Fidget-Spinner @picnixz @colesbury
gh-121459: Deferred LOAD_GLOBAL (GH-123128)
8810e28 
Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>
Co-authored-by: Sam Gross <655866+colesbury@users.noreply.github.com>
zware added a commit to zware/cpython that referenced this issue Sep 13, 2024
@zware
Revert "pythongh-121459: Deferred LOAD_GLOBAL (pythonGH-123128)"
3563dbd 
This reverts commit 8810e28.
colesbury added a commit to colesbury/cpython that referenced this issue Sep 14, 2024
@colesbury
Revert "pythongh-121459: Deferred LOAD_GLOBAL (pythonGH-123128)"
831d5fa 
This reverts commit 8810e28.
colesbury added a commit to colesbury/cpython that referenced this issue Sep 14, 2024
@colesbury
pythongh-121459: Add missing return to _PyDict_LoadGlobalStackRef
c8c59a1 
We need to return immediately if there's an error during dictionary
lookup.

Also avoid the conditional-if operator. The Windows 10 buildbot seems to
miscompile that for unknown reasons.
@bedevere-app bedevere-app bot mentioned this issue Sep 14, 2024
Merged
colesbury added a commit that referenced this issue Sep 14, 2024
@colesbury
gh-121459: Add missing return to _PyDict_LoadGlobalStackRef (#124085)
401fff7 
We need to return immediately if there's an error during dictionary
lookup.

Also avoid the conditional-if operator. MSVC versions through v19.27 miscompile
compound literals with side effects within a conditional operator. This caused
crashes in the Windows10 buildbot.
@bedevere-app bedevere-app bot mentioned this issue Sep 15, 2024
Closed
savannahostrowski pushed a commit to savannahostrowski/cpython that referenced this issue Sep 22, 2024
@colesbury @savannahostrowski
pythongh-121459: Add missing return to _PyDict_LoadGlobalStackRef (py…
eeca0b5 
…thon#124085)

We need to return immediately if there's an error during dictionary
lookup.

Also avoid the conditional-if operator. MSVC versions through v19.27 miscompile
compound literals with side effects within a conditional operator. This caused
crashes in the Windows10 buildbot.
@bedevere-app bedevere-app bot mentioned this issue Oct 2, 2024
Merged
markshannon added a commit that referenced this issue Oct 7, 2024
@markshannon
GH-121459: Streamline PyObject* to PyStackRef conversions by disallow…
d1453f6 
…ing NULL pointers. (GH-124894)
@bedevere-app bedevere-app bot mentioned this issue Oct 18, 2024
Merged
mpage added a commit that referenced this issue Oct 21, 2024
@mpage
gh-121459: Fix a couple of uses of PyStackRef_FromPyObjectSteal (#1…
de5a6c7 
…25711)

* Fix usage of PyStackRef_FromPyObjectSteal in CALL_TUPLE_1

This was missed in gh-124894

* Fix usage of PyStackRef_FromPyObjectSteal in _CALL_STR_1

This was missed in gh-124894

* Regenerate code
@Fidget-Spinner
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This is implemented now.

@picnixz
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picnixz commented Dec 14, 2024

What about #124101? should this one be considered as optional?

@Fidget-Spinner
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@picnixz I'm waiting for the porting over the specializing intepreter to free threaded build to play out. If that works for LOAD_ATTR we wont need the PR anymore.

ebonnal pushed a commit to ebonnal/cpython that referenced this issue Jan 12, 2025
@mpage @ebonnal
pythongh-121459: Fix a couple of uses of `PyStackRef_FromPyObjectStea…
6aafe7a 
…l` (python#125711)

* Fix usage of PyStackRef_FromPyObjectSteal in CALL_TUPLE_1

This was missed in pythongh-124894

* Fix usage of PyStackRef_FromPyObjectSteal in _CALL_STR_1

This was missed in pythongh-124894

* Regenerate code
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