This PR sets up tagged pointers for CPython.
The general idea is to create a separate struct _PyStackRef for everything on the evaluation stack to store the bits. This forces the C compiler to warn us if we try to cast things or pull things out of the struct directly.
Only for free threading: We tag the low bit if something is deferred - that means we skip incref and decref operations on it. This behavior may change in the future if Mark's plans to defer all objects in the interpreter loop pans out.
This implies a strict stack reference discipline is required. ALL incref and decref operations on stackrefs must use the stackref variants. It is unsafe to untag something then do normal incref/decref ops on it.
The new incref and decref variants are called dup and close. They mimic a "handle" API operating on these stackrefs.
Please read Include/internal/pycore_stackref.h for more information!
---------
Co-authored-by: Mark Shannon <9448417+markshannon@users.noreply.github.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>
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()).
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.
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`.
We make use of the same mechanism that we use for the static builtin types. This required a few tweaks.
The relevant code could use some cleanup but I opted to avoid the significant churn in this change. I'll tackle that separately.
This change is the final piece needed to make _datetime support multiple interpreters. I've updated the module slot accordingly.
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.
Only call `gc_restore_tid()` from stop-the-world contexts.
`worklist_pop()` can be called while other threads are running, so use a
relaxed atomic to modify `ob_tid`.
The Full Grammar specification in the docs omits rule actions, so grammar rules that raise a syntax error looked like valid syntax.
This was solved in ef940de by hiding those rules in the custom syntax highlighter.
This moves all syntax-error alternatives to invalid rules, adds a validator that ensures that actions containing RAISE_SYNTAX_ERROR are in invalid rules, and reverts the syntax highlighter hack.
When the _Py_SINGLETON() is used, Argument Clinic now adds an
explicit "pycore_runtime.h" include to get the macro. Previously, the
macro may or may not be included indirectly by another include.
ensurepip forks a subprocess to run pip itself, but that subprocess only inherits a -I isolated mode flag (see _run_pip() in Lib/ensurepip/__init__.py), not the "-E -s" flags that the installer has been using. This means that parts of ensurepip don't actually run in an isolated environment and can make incorrect decisions based on packages installed in the user site-packages.
_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.
This ensures we don't lose races that occur in subprocesses or
interleave races from workers running in parallel.
Log files are collected and packaged into a zipfile that can be
downloaded from the "Artifacts" section of the workflow run.
`_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.
Using `race:` filters out warnings if the function appears anywhere in
the stack trace. This can hide a lot of unrelated warnings, especially
for a function like `_PyEval_EvalFrameDefault`, which is somewhere on
the stack more often than not.
Change all free-threaded suppressions to `race_top:`, which only matches
the top frame, and add any new suppressions this exposes.
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.
The module itself is a thin wrapper around calls to functions in
`Python/codecs.c`, so that's where the meaningful changes happened:
- Move codecs-related state that lives on `PyInterpreterState` to a
struct declared in `pycore_codecs.h`.
- In free-threaded builds, add a mutex to `codecs_state` to synchronize
operations on `search_path`. Because `search_path_mutex` is used as a
normal mutex and not a critical section, we must be extremely careful
with operations called while holding it.
- The codec registry is explicitly initialized as part of
`_PyUnicode_InitEncodings` to simplify thread-safety.
The code for Tier 2 is now only compiled when configured
with `--enable-experimental-jit[=yes|interpreter]`.
We drop support for `PYTHON_UOPS` and -`Xuops`,
but you can disable the interpreter or JIT
at runtime by setting `PYTHON_JIT=0`.
You can also build it without enabling it by default
using `--enable-experimental-jit=yes-off`;
enable with `PYTHON_JIT=1`.
On Windows, the `build.bat` script supports
`--experimental-jit`, `--experimental-jit-off`,
`--experimental-interpreter`.
In the C code, `_Py_JIT` is defined as before
when the JIT is enabled; the new variable
`_Py_TIER2` is defined when the JIT *or* the
interpreter is enabled. It is actually a bitmask:
1: JIT; 2: default-off; 4: interpreter.
Makes sys.settrace, sys.setprofile, and monitoring generally thread-safe.
Mostly uses a stop-the-world approach and synchronization around the code object's _co_instrumentation_version. There may be a little bit of extra synchronization around the monitoring data that's required to be TSAN clean.
Quiet erroneous TSAN reports of data races in `_PySeqLock`
TSAN reports a couple of data races between the compare/exchange in
`_PySeqLock_LockWrite` and the non-atomic loads in `_PySeqLock_{Abandon,Unlock}Write`.
This is another instance of TSAN incorrectly modeling failed compare/exchange
as a write instead of a load.
Fix data races in the method cache in free-threaded builds
These are technically data races, but I think they're benign (to
the extent that that is actually possible). We update cache entries
non-atomically but read them atomically from another thread, and there's
nothing that establishes a happens-before relationship between the
reads and writes that I can see.
Additionally, reduce the iterations for a few weakref tests that would
otherwise take a prohibitively long amount of time (> 1 hour) when TSAN
is enabled and the GIL is disabled.
* Move ifndef_symbols, includes and add_include() from Clinic to
Codegen. Add a 'codegen' (Codegen) attribute to Clinic.
* Remove libclinic.crenderdata module: move code to libclinic.codegen.
* BlockPrinter.print_block(): remove unused 'limited_capi' argument.
Remove also 'core_includes' parameter.
* Add get_includes() methods.
* Make Codegen.ifndef_symbols private.
* Make Codegen.includes private.
* Make CConverter.includes private.
Introduce a unified 16-bit backoff counter type (``_Py_BackoffCounter``),
shared between the Tier 1 adaptive specializer and the Tier 2 optimizer. The
API used for adaptive specialization counters is changed but the behavior is
(supposed to be) identical.
The behavior of the Tier 2 counters is changed:
- There are no longer dynamic thresholds (we never varied these).
- All counters now use the same exponential backoff.
- The counter for ``JUMP_BACKWARD`` starts counting down from 16.
- The ``temperature`` in side exits starts counting down from 64.
Add libclinic.clanguage module and move the following classes and
functions there:
* CLanguage
* declare_parser()
Add libclinic.codegen and move the following classes there:
* BlockPrinter
* BufferSeries
* Destination
Move the following functions to libclinic.function:
* permute_left_option_groups()
* permute_optional_groups()
* permute_right_option_groups()
* Add a new create_parser_namespace() function for
PythonParser to pass objects to executed code.
* In run_clinic(), list converters using 'converters' and
'return_converters' dictionarties.
* test_clinic: add 'object()' return converter.
* Use also create_parser_namespace() in eval_ast_expr().
Co-authored-by: Erlend E. Aasland <erlend@python.org>
I added it quite a while ago as a strategy for managing interpreter lifetimes relative to the PEP 554 (now 734) implementation. Relatively recently I refactored that implementation to no longer rely on InterpreterID objects. Thus now I'm removing it.
Add Py_GetConstant() and Py_GetConstantBorrowed() functions.
In the limited C API version 3.13, getting Py_None, Py_False,
Py_True, Py_Ellipsis and Py_NotImplemented singletons is now
implemented as function calls at the stable ABI level to hide
implementation details. Getting these constants still return borrowed
references.
Add _testlimitedcapi/object.c and test_capi/test_object.py to test
Py_GetConstant() and Py_GetConstantBorrowed() functions.
Keep Tools/build/deepfreeze.py around (we may repurpose it for deepfreezing non-code objects),
and keep basic "clean" targets that remove the output of former deep-freeze activities,
to keep the build directories of current devs clean.
* Move Block and BlockParser classes to a new libclinic.block_parser
module.
* Move Language and PythonLanguage classes to a new
libclinic.language module.
The fildes converter of Argument Clinic now always call
PyObject_AsFileDescriptor(), not only for the limited C API.
The _PyLong_FileDescriptor_Converter() converter stays as a fallback
when PyObject_AsFileDescriptor() cannot be used.
dependabot[bot]
Sergey B Kirpichev
Ken Jin
Mark Shannon
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Petr Viktorin
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yf-yang
Diego Russo
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Daniele Parmeggiani
Sam Gross
Kirill Podoprigora
AN Long
neonene
Eric Snow
Steve Dower
Nikita Sobolev
Donghee Na
Katie Bell
Irit Katriel
Serhiy Storchaka
Xie Yanbo
Michael Vincent
Arnon Yaari
Seth Michael Larson
Miro Hrončok
Michał Górny
mpage
Alex Turner
Brett Simmers
trag1c
Pablo Galindo Salgado
Tian Gao
Savannah Ostrowski
Jelle Zijlstra
Andrej
Guido van Rossum
Alex Turner
Dino Viehland
David Rubin
Jeff Glass
Erlend E. Aasland
Michael Droettboom