The `zip_next` function uses a common optimization technique for methods
that generate tuples. The iterator maintains an internal reference to
the returned tuple. When the method is called again, it checks if the
internal tuple's reference count is 1. If so, the tuple can be reused.
However, this approach is not safe under the free-threading build:
after checking the reference count, another thread may perform the same
check and also reuse the tuple. This can result in a double decref on
the items of the replaced tuple and a double incref (memory leak) on
the items of the tuple being set.
This adds a function, `_PyObject_IsUniquelyReferenced` that
encapsulates the stricter logic necessary for the free-threaded build:
the internal tuple must be owned by the current thread, have a local
refcount of one, and a shared refcount of zero.
`Py_DECREF` and `PyStackRef_CLOSE` are now implemented as macros in the
free-threaded build in ceval.c. There are two motivations;
* MSVC has problems inlining functions in ceval.c in the PGO build.
* We will want to mark escaping calls in order to spill the stack
pointer in ceval.c and we will want to do this around `_Py_Dealloc`
(or `_Py_MergeZeroLocalRefcount` or `_Py_DecRefShared`), not around
the entire `Py_DECREF` or `PyStackRef_CLOSE` call.
The free-threaded GC now visits interpreter stacks to keep objects
that use deferred reference counting alive.
Interpreter frames are zero initialized in the free-threaded GC so
that the GC doesn't see garbage data. This is a temporary measure
until stack spilling around escaping calls is implemented.
Co-authored-by: Ken Jin <kenjin@python.org>
As of 529a160 (gh-118204), building with HAVE_DYNAMIC_LOADING stopped working. This is a minimal fix just to get builds working again. There are actually a number of long-standing deficiencies with HAVE_DYNAMIC_LOADING builds that need to be resolved separately.
This replaces `_PyList_FromArraySteal` with `_PyList_FromStackRefSteal`.
It's functionally equivalent, but takes a `_PyStackRef` array instead of
an array of `PyObject` pointers.
Co-authored-by: Ken Jin <kenjin@python.org>
`BUILD_SET` should use a borrow instead of a steal. The cleanup in `_DO_CALL`
`CONVERSION_FAILED` was incorrect.
Co-authored-by: Ken Jin <kenjin@python.org>
We were not properly accounting for interpreter memory leaks at
shutdown and had two sources of leaks:
* Objects that use deferred reference counting and were reachable via
static types outlive the final GC. We now disable deferred reference
counting on all objects if we are calling the GC due to interpreter
shutdown.
* `_PyMem_FreeDelayed` did not properly check for interpreter shutdown
so we had some memory blocks that were enqueued to be freed, but
never actually freed.
* `_PyType_FinalizeIdPool` wasn't called at interpreter shutdown.
Fix _PyArg_UnpackKeywordsWithVararg for the case when argument for
positional-or-keyword parameter is passed by keyword.
There was only one such case in the stdlib -- the TypeVar constructor.
This automatically spills the results from `_PyStackRef_FromPyObjectNew`
to the in-memory stack so that the deferred references are visible to
the GC before we make any possibly escaping call.
Co-authored-by: Ken Jin <kenjin@python.org>
Fix PyEval_GetLocals() to avoid SystemError ("bad argument to
internal function"). Don't redefine the 'ret' variable in the if
block.
Add an unit test on PyEval_GetLocals().
The free-threaded build partially stores heap type reference counts in
distributed manner in per-thread arrays. This avoids reference count
contention when creating or destroying instances.
Co-authored-by: Ken Jin <kenjin@python.org>
Add ENTER_RECURSIVE and LEAVE_RECURSIVE macros in ast.c, ast_opt.c and
symtable.c. Remove VISIT_QUIT macro in symtable.c.
The current recursion depth counter only needs to be updated during
normal execution -- all functions should just return an error code
if an error occurs.
* gh-122188: Move magic number to its own file
* Add versionadded directive
* Do work in C
* Integrate launcher.c
* Make _pyc_magic_number private
* Remove metadata
* Move sys.implementation -> _imp
* Modernize comment
* Move _RAW_MAGIC_NUMBER to the C side as well
* _pyc_magic_number -> pyc_magic_number
* Remove unused import
* Update docs
* Apply suggestions from code review
Co-authored-by: Eric Snow <ericsnowcurrently@gmail.com>
* Fix typo in tests
---------
Co-authored-by: Eric Snow <ericsnowcurrently@gmail.com>
The adaptive counter doesn't do anything currently in the free-threaded
build and TSan reports a data race due to concurrent modifications to
the counter.
* Use compensated summation for complex sums with floating-point items.
This amends #121176.
* sum() specializations for floats and complexes now use
PyLong_AsDouble() instead of PyLong_AsLongAndOverflow() and
compensated summation as well.
In the free-threaded build, we need to lock pending->mutex when clearing
the handling_thread in order not to race with a concurrent
make_pending_calls in the same interpreter.
This combines and updates our freelist handling to use a consistent
implementation. Objects in the freelist are linked together using the
first word of memory block.
If configured with freelists disabled, these operations are essentially
no-ops.
* Reject uop definitions that declare values as 'unused' that are already cached by prior uops
* Track which variables are defined and only load from memory when needed
* Support explicit `flush` in macro definitions.
* Make sure stack is flushed in where needed.
Kirill Podoprigora
Irit Katriel
Victor Stinner
Serhiy Storchaka
Bogdan Romanyuk
Pieter Eendebak
Mark Shannon
Anthony Shaw
Sam Gross
Donghee Na
Brandt Bucher
Pablo Galindo Salgado
Eric Snow
Tian Gao
sobolevn
neonene
Jelle Zijlstra
jianghuyiyuan
Michael Droettboom
Petr Viktorin
Sergey B Kirpichev
mpage