PyMutex is a one byte lock with fast, inlineable lock and unlock functions for the common uncontended case. The design is based on WebKit's WTF::Lock.
PyMutex is built using the _PyParkingLot APIs, which provides a cross-platform futex-like API (based on WebKit's WTF::ParkingLot). This internal API will be used for building other synchronization primitives used to implement PEP 703, such as one-time initialization and events.
This also includes tests and a mini benchmark in Tools/lockbench/lockbench.py to compare with the existing PyThread_type_lock.
Uncontended acquisition + release:
* Linux (x86-64): PyMutex: 11 ns, PyThread_type_lock: 44 ns
* macOS (arm64): PyMutex: 13 ns, PyThread_type_lock: 18 ns
* Windows (x86-64): PyMutex: 13 ns, PyThread_type_lock: 38 ns
PR Overview:
The primary purpose of this PR is to implement PyMutex, but there are a number of support pieces (described below).
* PyMutex: A 1-byte lock that doesn't require memory allocation to initialize and is generally faster than the existing PyThread_type_lock. The API is internal only for now.
* _PyParking_Lot: A futex-like API based on the API of the same name in WebKit. Used to implement PyMutex.
* _PyRawMutex: A word sized lock used to implement _PyParking_Lot.
* PyEvent: A one time event. This was used a bunch in the "nogil" fork and is useful for testing the PyMutex implementation, so I've included it as part of the PR.
* pycore_llist.h: Defines common operations on doubly-linked list. Not strictly necessary (could do the list operations manually), but they come up frequently in the "nogil" fork. ( Similar to https://man.freebsd.org/cgi/man.cgi?queue)
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Co-authored-by: Eric Snow <ericsnowcurrently@gmail.com>
Symbols of the C API should be prefixed by "Py_" to avoid conflict
with existing names in 3rd party C extensions on "#include <Python.h>".
test.pythoninfo now logs Py_C_RECURSION_LIMIT constant and other
_testcapi and _testinternalcapi constants.
Statistics gathering is now off by default. Use the "-X pystats"
command line option or set the new PYTHONSTATS environment variable
to 1 to turn statistics gathering on at Python startup.
Statistics are no longer dumped at exit if statistics gathering was
off or statistics have been cleared.
Changes:
* Add PYTHONSTATS environment variable.
* sys._stats_dump() now returns False if statistics are not dumped
because they are all equal to zero.
* Add PyConfig._pystats member.
* Add tests on sys functions and on setting PyConfig._pystats to 1.
* Add Include/cpython/pystats.h and Include/internal/pycore_pystats.h
header files.
* Rename '_py_stats' variable to '_Py_stats'.
* Exclude Include/cpython/pystats.h from the Py_LIMITED_API.
* Move pystats.h include from object.h to Python.h.
* Add _Py_StatsOn() and _Py_StatsOff() functions. Remove
'_py_stats_struct' variable from the API: make it static in
specialize.c.
* Document API in Include/pystats.h and Include/cpython/pystats.h.
* Complete pystats documentation in Doc/using/configure.rst.
* Don't write "all zeros" stats: if _stats_off() and _stats_clear()
or _stats_dump() were called.
* _PyEval_Fini() now always call _Py_PrintSpecializationStats() which
does nothing if stats are all zeros.
Co-authored-by: Michael Droettboom <mdboom@gmail.com>
Move the private _PyErr_WriteUnraisableMsg() functions to the
internal C API (pycore_pyerrors.h).
Move write_unraisable_exc() from _testcapi to _testinternalcapi.
Move the private _PyLong_Sign() and _PyLong_NumBits() functions
to the internal C API (pycore_long.h).
Modules/_testcapi/long.c now uses the internal C API.
This adds a new header that provides atomic operations on common data
types. The intention is that this will be exposed through Python.h,
although that is not the case yet. The only immediate use is in
the test file.
Co-authored-by: Sam Gross <colesbury@gmail.com>
Remove _PyErr_ChainExceptions(), _PyErr_ChainExceptions1() and
_PyErr_SetFromPyStatus() functions from the public C API.
* Move the private _PyErr_ChainExceptions() and
_PyErr_ChainExceptions1() function to the internal C API
(pycore_pyerrors.h).
* Move the private _PyErr_SetFromPyStatus() to the internal C API
(pycore_initconfig.h).
* No longer export the _PyErr_ChainExceptions() function.
* Move run_in_subinterp_with_config() from _testcapi to
_testinternalcapi.
Move PyUnstable_ExecutableKinds and associated macros from the
internal C API to the public C API.
Rename constants: replace "PY_" prefix with "PyUnstable_" prefix.
Move the following private API to the internal C API (pycore_long.h):
* _PyLong_Copy()
* _PyLong_FromDigits()
* _PyLong_New()
No longer export most of these functions.
The remove private _PyGILState_GetInterpreterStateUnsafe() function
from the public C API: move it the internal C API (pycore_pystate.h).
No longer export the function.
The remove private _Py_UniversalNewlineFgetsWithSize() function from
the public C API: move it the internal C API (pycore_fileutils.h).
No longer export the function.
Remove these private functions from the public C API:
* _PyRun_AnyFileObject()
* _PyRun_InteractiveLoopObject()
* _PyRun_SimpleFileObject()
* _Py_SourceAsString()
Move them to the internal C API: add a new pycore_pythonrun.h header
file. No longer export these functions.
Remove the private _Py_Identifier type and related private functions
from the public C API:
* _PyObject_GetAttrId()
* _PyObject_LookupSpecialId()
* _PyObject_SetAttrId()
* _PyType_LookupId()
* _Py_IDENTIFIER()
* _Py_static_string()
* _Py_static_string_init()
Move them to the internal C API: add a new pycore_identifier.h header
file. No longer export these functions.
* Rename _PyUnstable_GetUnaryIntrinsicName() to
PyUnstable_GetUnaryIntrinsicName()
* Rename _PyUnstable_GetBinaryIntrinsicName()
to PyUnstable_GetBinaryIntrinsicName().
Move these private functions to the internal C API
(pycore_abstract.h):
* _Py_convert_optional_to_ssize_t()
* _PyNumber_Index()
Argument Clinic now emits #include "pycore_abstract.h" when these
functions are used.
The parser of the c-analyzer tool now uses a list of files which use
the limited C API, rather than a list of files using the internal C
API.
Move the private _PyLong converter functions to the internal C API
* _PyLong_FileDescriptor_Converter(): moved to pycore_fileutils.h
* _PyLong_Size_t_Converter(): moved to pycore_long.h
Argument Clinic now emits includes for pycore_fileutils.h and
pycore_long.h when these functions are used.
Move these private functions to the internal C API (pycore_long.h):
* _PyLong_UnsignedInt_Converter()
* _PyLong_UnsignedLongLong_Converter()
* _PyLong_UnsignedLong_Converter()
* _PyLong_UnsignedShort_Converter()
Argument Clinic now emits #include "pycore_long.h" when these
functions are used.
Move private functions to the internal C API (pycore_sysmodule.h):
* _PySys_GetAttr()
* _PySys_GetSizeOf()
No longer export most of these functions.
Fix also a typo in Include/cpython/optimizer.h: add a missing space.
Move private functions to the internal C API (pycore_dict.h):
* _PyDictView_Intersect()
* _PyDictView_New()
* _PyDict_ContainsId()
* _PyDict_DelItemId()
* _PyDict_DelItem_KnownHash()
* _PyDict_GetItemIdWithError()
* _PyDict_GetItem_KnownHash()
* _PyDict_HasSplitTable()
* _PyDict_NewPresized()
* _PyDict_Next()
* _PyDict_Pop()
* _PyDict_SetItemId()
* _PyDict_SetItem_KnownHash()
* _PyDict_SizeOf()
No longer export most of these functions.
Move also the _PyDictViewObject structure to the internal C API.
Move dict_getitem_knownhash() function from _testcapi to the
_testinternalcapi extension. Update test_capi.test_dict for this
change.
Move private _PyEval functions to the internal C API
(pycore_ceval.h):
* _PyEval_GetBuiltin()
* _PyEval_GetBuiltinId()
* _PyEval_GetSwitchInterval()
* _PyEval_MakePendingCalls()
* _PyEval_SetProfile()
* _PyEval_SetSwitchInterval()
* _PyEval_SetTrace()
No longer export most of these functions.
Remove private _PyDict_GetItemStringWithError() function of the
public C API: the new PyDict_GetItemStringRef() can be used instead.
* Move private _PyDict_GetItemStringWithError() to the internal C API.
* _testcapi get_code_extra_index() uses PyDict_GetItemStringRef().
Avoid using private functions in _testcapi which tests the public C
API.
The _xxsubinterpreters module should not rely on internal API. Some of the functions it uses were recently moved there however. Here we move them back (and expose them properly).
We tried this before with a dict and for all interned strings. That ran into problems due to interpreter isolation. However, exclusively using a per-interpreter cache caused some inconsistency that can eliminate the benefit of interning. Here we circle back to using a global cache, but only for statically allocated strings. We also use a more-basic _Py_hashtable_t for that global cache instead of a dict.
Ideally we would only have the global cache, but the optional isolation of each interpreter's allocator means that a non-static string object must not outlive its interpreter. Thus we would have to store a copy of each such interned string in the global cache, tied to the main interpreter.
Move PyInterpreterConfig structure and associated macros from
initconfig.h to pylifecycle.h: it's not related to the Python
Initialization Configuration.
Declare the following 3 PyUnstable functions in
Include/cpython/pyframe.h rather than Include/cpython/frameobject.h,
so they are now provided by the standard "#include <Python.h>".
Move private _PyMem functions to the internal C API (pycore_pymem.h):
* _PyMem_GetCurrentAllocatorName()
* _PyMem_RawStrdup()
* _PyMem_RawWcsdup()
* _PyMem_Strdup()
No longer export these functions.
Move pymem_getallocatorsname() function from _testcapi to _testinternalcapi,
since the API moved to the internal C API.
