This exposes `PyUnstable_Object_ClearWeakRefsNoCallbacks` as an unstable
C-API function to provide a thread-safe mechanism for clearing weakrefs
without executing callbacks.
Some C-API extensions need to clear weakrefs without calling callbacks,
such as after running finalizers like we do in subtype_dealloc.
Previously they could use `_PyWeakref_ClearRef` on each weakref, but
that's not thread-safe in the free-threaded build.
(cherry picked from commit e8752d7b80)
Co-authored-by: Sam Gross <colesbury@gmail.com>
Co-authored-by: Petr Viktorin <encukou@gmail.com>
gh-117657: Make PyType_HasFeature (exported version) atomic (GH-120484)
Make PyType_HasFeature (exported version) atomic
(cherry picked from commit 6f63dfff6f)
Co-authored-by: Ken Jin <kenjin@python.org>
In gh-120009 I used an atexit hook to finalize the _datetime module's static types at interpreter shutdown. However, atexit hooks are executed very early in finalization, which is a problem in the few cases where a subclass of one of those static types is still alive until the final GC collection. The static builtin types don't have this probably because they are finalized toward the end, after the final GC collection. To avoid the problem for _datetime, I have applied a similar approach here.
Also, credit goes to @mgorny and @neonene for the new tests.
FYI, I would have liked to take a slightly cleaner approach with managed static types, but wanted to get a smaller fix in first for the sake of backporting. I'll circle back to the cleaner approach with a future change on the main branch.
(cherry picked from commit b2e71ff4f8, AKA gh-120182)
Co-authored-by: Eric Snow <ericsnowcurrently@gmail.com>
gh-117657: Make PyType_HasFeature atomic (GH-120210)
Make PyType_HasFeature atomic
(cherry picked from commit eebae2c460)
Co-authored-by: Ken Jin <kenjin@python.org>
The _strptime module object was cached in a static local variable (in the datetime.strptime() implementation). That's a problem when it crosses isolation boundaries, such as reinitializing the runtme or between interpreters. This change fixes the problem by dropping the static variable, instead always relying on the normal sys.modules cache (via PyImport_Import()).
(cherry picked from commit 127c1d2771, AKA gh-120224)
Co-authored-by: neonene <53406459+neonene@users.noreply.github.com>
gh-120326: Include <intrin.h> on Windows with Free Threading (GH-120329)
(cherry picked from commit 939c201e00)
Co-authored-by: Kirill Podoprigora <kirill.bast9@mail.ru>
gh-117657: Make Py_TYPE and Py_SET_TYPE thread safe (GH-120165)
(cherry picked from commit e16aed63f6)
Co-authored-by: Ken Jin <kenjin@python.org>
Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>
Co-authored-by: Nadeshiko Manju <me@manjusaka.me>
This adds a `_PyRecursiveMutex` type based on `PyMutex` and uses that
for the import lock. This fixes some data races in the free-threaded
build and generally simplifies the import lock code.
(cherry picked from commit e21057b999)
Co-authored-by: Sam Gross <colesbury@gmail.com>
The `_PyThreadState_Bind()` function is called before the first
`PyEval_AcquireThread()` so it's not synchronized with the stop the
world GC. We had a race where `gc_visit_heaps()` might visit a thread's
heap while it's being initialized.
Use a simple atomic int to avoid visiting heaps for threads that are not
yet fully initialized (i.e., before `tstate_mimalloc_bind()` is called).
The race was reproducible by running:
`python Lib/test/test_importlib/partial/pool_in_threads.py`.
(cherry picked from commit e69d068ad0)
Co-authored-by: Sam Gross <colesbury@gmail.com>
We make use of the same mechanism that we use for the static builtin types. This required a few tweaks.
This change is the final piece needed to make _datetime support multiple interpreters. I've updated the module slot accordingly.
(cherry picked from commit 105f22ea46, AKA gh-119929)
Co-authored-by: Eric Snow <ericsnowcurrently@gmail.com>
I was able to make use of the existing datetime_state struct, but there was one tricky thing I had to sort out. We mostly aren't converting to heap types, so we can't use things like PyType_GetModuleByDef() to look up the module state. The solution I came up with is somewhat novel, but I consider it straightforward. Also, it shouldn't have much impact on performance.
In summary, this main changes here are:
* I've added some macros to help hide how various objects relate to module state
* as a solution to the module state lookup problem, I've stored the last loaded module on the current interpreter's internal dict (actually a weakref)
* if the static type method is used after the module has been deleted, it is reloaded
* to avoid extra work when loading the module, we directly copy the objects (new refs only) from the old module state into the new state if the old module hasn't been deleted yet
* during module init we set various objects on the static types' __dict__s; to simplify things, we only do that the first time; once those static types have a separate __dict__ per interpreter, we'll do it every time
* we now clear the module state when the module is destroyed (before, we were leaking everything in _datetime_global_state)
(cherry picked from commit d82a7ba041, AKA gh-119810)
Co-authored-by: Eric Snow <ericsnowcurrently@gmail.com>
The free-threaded build currently immortalizes objects that use deferred
reference counting (see gh-117783). This typically happens once the
first non-main thread is created, but the behavior can be suppressed for
tests, in subinterpreters, or during a compile() call.
This fixes a race condition involving the tracking of whether the
behavior is suppressed.
(cherry picked from commit 47fb4327b5)
gh-119336: Restore removed _PyLong_NumBits() function (GH-119418)
It is used by the pywin32 project.
(cherry picked from commit e50fac96e8)
Co-authored-by: Ethan Smith <ethan@ethanhs.me>
The GIL may be disabled concurrently with this call so we need to use a
relaxed atomic load.
(cherry picked from commit f3b89a63cb)
Co-authored-by: Sam Gross <colesbury@gmail.com>
dSupport non-dict globals in LOAD_FROM_DICT_OR_GLOBALS
The implementation basically copies LOAD_GLOBAL. Possibly it could be deduplicated,
but that seems like it may get hairy since the two operations have different operands.
This is important to fix in 3.14 for PEP 649, but it's a bug in earlier versions too,
and we should backport to 3.13 and 3.12 if possible.
(cherry picked from commit 80a4e38994)
The free-threaded refleak builds were reporting negative refcount deltas
in some tests because of a missing `_Py_NewRefWithLock`.
(cherry picked from commit 879d43b705)
Co-authored-by: Sam Gross <colesbury@gmail.com>
`drop_gil()` assumes that its caller is attached, which means that the current
thread holds the GIL if and only if the GIL is enabled, and the enabled-state
of the GIL won't change. This isn't true, though, because `detach_thread()`
calls `_PyEval_ReleaseLock()` after detaching and
`_PyThreadState_DeleteCurrent()` calls it after removing the current thread
from consideration for stop-the-world requests (effectively detaching it).
Fix this by remembering whether or not a thread acquired the GIL when it last
attached, in `PyThreadState._status.holds_gil`, and check this in `drop_gil()`
instead of `gil->enabled`.
This fixes a crash in `test_multiprocessing_pool_circular_import()`, so I've
reenabled it.
(cherry picked from commit be1dfccdf2)
Co-authored-by: Brett Simmers <swtaarrs@users.noreply.github.com>
Add `Py_BEGIN_CRITICAL_SECTION_SEQUENCE_FAST` and
`Py_END_CRITICAL_SECTION_SEQUENCE_FAST` macros and update `str.join` to use
them. Also add a regression test that would crash reliably without this
patch.
(cherry picked from commit baf347d916)
Co-authored-by: Josh {*()} Rosenberg <26495692+MojoVampire@users.noreply.github.com>
_PyArg_Parser holds static global data generated for modules by Argument Clinic. The _PyArg_Parser.kwtuple field is a tuple object, even though it's stored within a static global. In some cases the tuple is statically allocated and thus it's okay that it gets shared by multiple interpreters. However, in other cases the tuple is set lazily, allocated from the heap using the active interprepreter at the point the tuple is needed.
This is a problem once that interpreter is destroyed since _PyArg_Parser.kwtuple becomes at dangling pointer, leading to crashes. It isn't a problem if the tuple is allocated under the main interpreter, since its lifetime is bound to the lifetime of the runtime. The solution here is to temporarily switch to the main interpreter. The alternative would be to always statically allocate the tuple.
This change also fixes a bug where only the most recent parser was added to the global linked list.
(cherry picked from commit 81865002ae)
Co-authored-by: Eric Snow <ericsnowcurrently@gmail.com>
`_Py_qsbr_unregister` is called when the PyThreadState is already
detached, so the access to `tstate->qsbr` isn't safe without locking the
shared mutex. Grab the `struct _qsbr_shared` from the interpreter
instead.
(cherry picked from commit 33d20199af)
Co-authored-by: Alex Turner <alexturner@meta.com>
gh-118789: Restore hidden `_PyWeakref_ClearRef` (GH-118797)
_PyWeakref_ClearRef was previously exposed in the public C-API, although
it begins with an underscore and is not documented. It's used by a few
C-API extensions. There is currently no alternative public API that can
replace its use.
_PyWeakref_ClearWeakRefsExceptCallbacks is the only thread-safe way to
use _PyWeakref_ClearRef in the free-threaded build. This exposes the C
symbol, but does not make the API public.
(cherry picked from commit db5af7da09)
Co-authored-by: Sam Gross <colesbury@gmail.com>
This reverts commit ad4f909e0e.
The API ended up not being used.
(cherry picked from commit 46c808172f)
Co-authored-by: Sam Gross <colesbury@gmail.com>
Some embedders and extensions include parts of the internal API. The
pycore_mimalloc.h file is transitively include by a number of other
internal headers. This avoids include errors for code that was
already including those headers.
(cherry picked from commit 71cc0651e7)
Co-authored-by: Sam Gross <colesbury@gmail.com>
Use relaxed atomics when reading / writing to the field. There are still a
few places in the GC where we do not use atomics. Those should be safe as
the world is stopped.
(cherry picked from commit cb6f75a32c)
Co-authored-by: mpage <mpage@meta.com>
Add the ability to enable/disable the GIL at runtime, and use that in
the C module loading code.
We can't know before running a module init function if it supports
free-threading, so the GIL is temporarily enabled before doing so. If
the module declares support for running without the GIL, the GIL is
later disabled. Otherwise, the GIL is permanently enabled, and will
never be disabled again for the life of the current interpreter.
We already intern and immortalize most string constants. In the
free-threaded build, other constants can be a source of reference count
contention because they are shared by all threads running the same code
objects.
Add _PyType_LookupRef and use incref before setting attribute on type
Makes setting an attribute on a class and signaling type modified atomic
Avoid adding re-entrancy exposing the type cache in an inconsistent state by decrefing after type is updated
The designated initializer syntax in static inline functions in pycore_backoff.h
causes problems for C++ or MSVC users who aren't yet using C++20.
While internal, pycore_backoff.h is included (indirectly, via pycore_code.h)
by some key 3rd party software that does so for speed.
Use the new public Raw functions:
* _PyTime_PerfCounterUnchecked() with PyTime_PerfCounterRaw()
* _PyTime_TimeUnchecked() with PyTime_TimeRaw()
* _PyTime_MonotonicUnchecked() with PyTime_MonotonicRaw()
Remove internal functions:
* _PyTime_PerfCounterUnchecked()
* _PyTime_TimeUnchecked()
* _PyTime_MonotonicUnchecked()
We have only been tracking each module's PyModuleDef. However, there are some problems with that. For example, in some cases we load single-phase init extension modules from def->m_base.m_init or def->m_base.m_copy, but if multiple modules share a def then we can end up with unexpected behavior.
With this change, we track the following:
* PyModuleDef (same as before)
* for some modules, its init function or a copy of its __dict__, but specific to that module
* whether it is a builtin/core module or a "dynamic" extension
* the interpreter (ID) that owns the cached __dict__ (only if cached)
This also makes it easier to remember the module's kind (e.g. single-phase init) and if loading it previously failed, which I'm doing separately.
Ken Jin