Refactor the fast Unicode hash check into `_PyObject_HashFast` and use relaxed
atomic loads in the free-threaded build.
After this change, the TSAN doesn't report data races for this method.
(cherry picked from commit 294e724964)
Co-authored-by: AN Long <aisk@users.noreply.github.com>
PyDict_Next no longer locks the dictionary in the free-threaded build. Locking
around individual PyDict_Next calls is not sufficient because the function
returns borrowed references and because it allows concurrent modifications
during the iteraiton loop.
The internal locking also interferes with correct external synchronization
because it may suspend outer critical sections created by the caller.
(cherry picked from commit 375b723d58)
Co-authored-by: Sam Gross <colesbury@gmail.com>
Moves the logic to update the type's dictionary to its own function in order
to make the lock scoping more clear.
Also, ensure that `name` is decref'd on the error path.
(cherry picked from commit dee63cb359)
Co-authored-by: Sam Gross <colesbury@gmail.com>
* Add an InternalDocs file describing how interning should work and how to use it.
* Add internal functions to *explicitly* request what kind of interning is done:
- `_PyUnicode_InternMortal`
- `_PyUnicode_InternImmortal`
- `_PyUnicode_InternStatic`
* Switch uses of `PyUnicode_InternInPlace` to those.
* Disallow using `_Py_SetImmortal` on strings directly.
You should use `_PyUnicode_InternImmortal` instead:
- Strings should be interned before immortalization, otherwise you're possibly
interning a immortalizing copy.
- `_Py_SetImmortal` doesn't handle the `SSTATE_INTERNED_MORTAL` to
`SSTATE_INTERNED_IMMORTAL` update, and those flags can't be changed in
backports, as they are now part of public API and version-specific ABI.
* Add private `_only_immortal` argument for `sys.getunicodeinternedsize`, used in refleak test machinery.
* Make sure the statically allocated string singletons are unique. This means these sets are now disjoint:
- `_Py_ID`
- `_Py_STR` (including the empty string)
- one-character latin-1 singletons
Now, when you intern a singleton, that exact singleton will be interned.
* Add a `_Py_LATIN1_CHR` macro, use it instead of `_Py_ID`/`_Py_STR` for one-character latin-1 singletons everywhere (including Clinic).
* Intern `_Py_STR` singletons at startup.
* For free-threaded builds, intern `_Py_LATIN1_CHR` singletons at startup.
* Beef up the tests. Cover internal details (marked with `@cpython_only`).
* Add lots of assertions
Co-authored-by: Eric Snow <ericsnowcurrently@gmail.com>
- gh-119521: Rename IncompleteInputError to _IncompleteInputError and remove from public API/ABI (GH-119680)
(cherry picked from commit ce1064e4c9)
- gh-119521: Use `PyAPI_DATA`, not `extern`, for `_PyExc_IncompleteInputError` (GH-120955)
(cherry picked from commit ac61d58db0)
Co-authored-by: Pablo Galindo Salgado <Pablogsal@gmail.com>
Co-authored-by: Petr Viktorin <encukou@gmail.com>
This makes the following macros public as part of the non-limited C-API for
locking a single object or two objects at once.
* `Py_BEGIN_CRITICAL_SECTION(op)` / `Py_END_CRITICAL_SECTION()`
* `Py_BEGIN_CRITICAL_SECTION2(a, b)` / `Py_END_CRITICAL_SECTION2()`
The supporting functions and structs used by the macros are also exposed for
cases where C macros are not available.
(cherry picked from commit 8f17d69b7b)
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-120182 added new global state (interp_count), but didn't add thread-safety for it. This change eliminates the possible race.
(cherry picked from commit 2c66318cdc, AKA gh-120529)
Co-authored-by: Eric Snow <ericsnowcurrently@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 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>
We need to write to `ob_ref_local` and `ob_tid` before `ob_ref_shared`.
Once we mark `ob_ref_shared` as merged, some other thread may free the
object because the caller also passes in `-1` as `extra` to give up its
only reference.
(cherry picked from commit 4055577221)
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>
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-117657: Fix data races report by TSAN unicode-hash (gh-119907)
(cherry picked from commit 0594a27e5f)
Co-authored-by: Donghee Na <donghee.na@python.org>
* Add docs for new APIs
* Add soft-deprecation notices
* Add What's New porting entries
* Update comments referencing `PyFrame_LocalsToFast()` to mention the proxy instead
* Other related cleanups found when looking for refs to the deprecated APIs
(cherry picked from commit 3859e09e3d)
Co-authored-by: Alyssa Coghlan <ncoghlan@gmail.com>
* Remove the equivalence with real+imag*1j which can be incorrect in corner
cases (non-finite numbers, the sign of zeroes).
* Separately document the three roles of the constructor: parsing a string,
converting a number, and constructing a complex from components.
* Document positional-only parameters of complex(), float(), int() and bool()
as positional-only.
* Add examples for complex() and int().
* Specify the grammar of the string for complex().
* Improve the grammar of the string for float().
* Describe more explicitly the behavior when real and/or imag arguments are
complex numbers. (This will be deprecated in future.)
(cherry picked from commit ec1ba26460)
Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
The deadlock only affected the free-threaded build and only occurred
when the GIL was enabled at runtime. The `Py_DECREF(old_name)` call
might temporarily release the GIL while holding the type seqlock.
Another thread may spin trying to acquire the seqlock while holding the
GIL.
The deadlock occurred roughly 1 in ~1,000 runs of `pool_in_threads.py`
from `test_multiprocessing_pool_circular_import`.
(cherry picked from commit c22323cd1c)
Co-authored-by: Sam Gross <colesbury@gmail.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>
gh-119053: Implement the fast path for list.__getitem__ (gh-119112)
(cherry picked from commit ab4263a82a)
Co-authored-by: Donghee Na <donghee.na@python.org>
The `list_preallocate_exact` function did not zero initialize array
contents. In the free-threaded build, this could expose uninitialized
memory to concurrent readers between the call to
`list_preallocate_exact` and the filling of the array contents with
items.
(cherry picked from commit 2402715e10)
Co-authored-by: Sam Gross <colesbury@gmail.com>
gh-118849: Fix "code will never be executed" warning in `dictobject.c` (GH-118850)
(cherry picked from commit 82abe75e77)
Co-authored-by: Nikita Sobolev <mail@sobolevn.me>
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>
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
Miss Islington (bot)
Petr Viktorin
Sam Gross
Mark Shannon
Tian Gao
James Hilton-Balfe
Dino Viehland
Thomas Grainger