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| -rw-r--r-- | Doc/c-api/extension-modules.rst | 247 | ||||
| -rw-r--r-- | Doc/c-api/index.rst | 1 | ||||
| -rw-r--r-- | Doc/c-api/init.rst | 30 | ||||
| -rw-r--r-- | Doc/c-api/intro.rst | 26 | ||||
| -rw-r--r-- | Doc/c-api/module.rst | 271 | ||||
| -rw-r--r-- | Doc/data/refcounts.dat | 3 | ||||
| -rw-r--r-- | Doc/extending/building.rst | 49 | ||||
| -rw-r--r-- | Doc/howto/perf_profiling.rst | 4 | ||||
| -rw-r--r-- | Doc/library/concurrency.rst | 1 | ||||
| -rw-r--r-- | Doc/library/concurrent.interpreters.rst | 198 | ||||
| -rw-r--r-- | Doc/library/concurrent.rst | 3 | ||||
| -rw-r--r-- | Doc/library/dataclasses.rst | 7 | ||||
| -rw-r--r-- | Doc/library/email.header.rst | 34 | ||||
| -rw-r--r-- | Doc/library/logging.config.rst | 2 | ||||
| -rw-r--r-- | Doc/library/math.rst | 4 | ||||
| -rw-r--r-- | Doc/library/python.rst | 5 | ||||
| -rw-r--r-- | Doc/library/stdtypes.rst | 27 | ||||
| -rw-r--r-- | Doc/library/sys.rst | 7 | ||||
| -rw-r--r-- | Doc/library/uuid.rst | 2 | ||||
| -rw-r--r-- | Doc/reference/expressions.rst | 5 | ||||
| -rw-r--r-- | Doc/using/configure.rst | 8 | ||||
| -rw-r--r-- | Doc/whatsnew/3.14.rst | 163 | ||||
| -rw-r--r-- | Doc/whatsnew/3.15.rst | 7 |
23 files changed, 833 insertions, 271 deletions
diff --git a/Doc/c-api/extension-modules.rst b/Doc/c-api/extension-modules.rst new file mode 100644 index 00000000000..4c8212f2f5e --- /dev/null +++ b/Doc/c-api/extension-modules.rst @@ -0,0 +1,247 @@ +.. highlight:: c + +.. _extension-modules: + +Defining extension modules +-------------------------- + +A C extension for CPython is a shared library (for example, a ``.so`` file +on Linux, ``.pyd`` DLL on Windows), which is loadable into the Python process +(for example, it is compiled with compatible compiler settings), and which +exports an :ref:`initialization function <extension-export-hook>`. + +To be importable by default (that is, by +:py:class:`importlib.machinery.ExtensionFileLoader`), +the shared library must be available on :py:attr:`sys.path`, +and must be named after the module name plus an extension listed in +:py:attr:`importlib.machinery.EXTENSION_SUFFIXES`. + +.. note:: + + Building, packaging and distributing extension modules is best done with + third-party tools, and is out of scope of this document. + One suitable tool is Setuptools, whose documentation can be found at + https://setuptools.pypa.io/en/latest/setuptools.html. + +Normally, the initialization function returns a module definition initialized +using :c:func:`PyModuleDef_Init`. +This allows splitting the creation process into several phases: + +- Before any substantial code is executed, Python can determine which + capabilities the module supports, and it can adjust the environment or + refuse loading an incompatible extension. +- By default, Python itself creates the module object -- that is, it does + the equivalent of :py:meth:`object.__new__` for classes. + It also sets initial attributes like :attr:`~module.__package__` and + :attr:`~module.__loader__`. +- Afterwards, the module object is initialized using extension-specific + code -- the equivalent of :py:meth:`~object.__init__` on classes. + +This is called *multi-phase initialization* to distinguish it from the legacy +(but still supported) *single-phase initialization* scheme, +where the initialization function returns a fully constructed module. +See the :ref:`single-phase-initialization section below <single-phase-initialization>` +for details. + +.. versionchanged:: 3.5 + + Added support for multi-phase initialization (:pep:`489`). + + +Multiple module instances +......................... + +By default, extension modules are not singletons. +For example, if the :py:attr:`sys.modules` entry is removed and the module +is re-imported, a new module object is created, and typically populated with +fresh method and type objects. +The old module is subject to normal garbage collection. +This mirrors the behavior of pure-Python modules. + +Additional module instances may be created in +:ref:`sub-interpreters <sub-interpreter-support>` +or after Python runtime reinitialization +(:c:func:`Py_Finalize` and :c:func:`Py_Initialize`). +In these cases, sharing Python objects between module instances would likely +cause crashes or undefined behavior. + +To avoid such issues, each instance of an extension module should +be *isolated*: changes to one instance should not implicitly affect the others, +and all state owned by the module, including references to Python objects, +should be specific to a particular module instance. +See :ref:`isolating-extensions-howto` for more details and a practical guide. + +A simpler way to avoid these issues is +:ref:`raising an error on repeated initialization <isolating-extensions-optout>`. + +All modules are expected to support +:ref:`sub-interpreters <sub-interpreter-support>`, or otherwise explicitly +signal a lack of support. +This is usually achieved by isolation or blocking repeated initialization, +as above. +A module may also be limited to the main interpreter using +the :c:data:`Py_mod_multiple_interpreters` slot. + + +.. _extension-export-hook: + +Initialization function +....................... + +The initialization function defined by an extension module has the +following signature: + +.. c:function:: PyObject* PyInit_modulename(void) + +Its name should be :samp:`PyInit_{<name>}`, with ``<name>`` replaced by the +name of the module. + +For modules with ASCII-only names, the function must instead be named +:samp:`PyInit_{<name>}`, with ``<name>`` replaced by the name of the module. +When using :ref:`multi-phase-initialization`, non-ASCII module names +are allowed. In this case, the initialization function name is +:samp:`PyInitU_{<name>}`, with ``<name>`` encoded using Python's +*punycode* encoding with hyphens replaced by underscores. In Python: + +.. code-block:: python + + def initfunc_name(name): + try: + suffix = b'_' + name.encode('ascii') + except UnicodeEncodeError: + suffix = b'U_' + name.encode('punycode').replace(b'-', b'_') + return b'PyInit' + suffix + +It is recommended to define the initialization function using a helper macro: + +.. c:macro:: PyMODINIT_FUNC + + Declare an extension module initialization function. + This macro: + + * specifies the :c:expr:`PyObject*` return type, + * adds any special linkage declarations required by the platform, and + * for C++, declares the function as ``extern "C"``. + +For example, a module called ``spam`` would be defined like this:: + + static struct PyModuleDef spam_module = { + .m_base = PyModuleDef_HEAD_INIT, + .m_name = "spam", + ... + }; + + PyMODINIT_FUNC + PyInit_spam(void) + { + return PyModuleDef_Init(&spam_module); + } + +It is possible to export multiple modules from a single shared library by +defining multiple initialization functions. However, importing them requires +using symbolic links or a custom importer, because by default only the +function corresponding to the filename is found. +See the `Multiple modules in one library <https://peps.python.org/pep-0489/#multiple-modules-in-one-library>`__ +section in :pep:`489` for details. + +The initialization function is typically the only non-\ ``static`` +item defined in the module's C source. + + +.. _multi-phase-initialization: + +Multi-phase initialization +.......................... + +Normally, the :ref:`initialization function <extension-export-hook>` +(``PyInit_modulename``) returns a :c:type:`PyModuleDef` instance with +non-``NULL`` :c:member:`~PyModuleDef.m_slots`. +Before it is returned, the ``PyModuleDef`` instance must be initialized +using the following function: + + +.. c:function:: PyObject* PyModuleDef_Init(PyModuleDef *def) + + Ensure a module definition is a properly initialized Python object that + correctly reports its type and a reference count. + + Return *def* cast to ``PyObject*``, or ``NULL`` if an error occurred. + + Calling this function is required for :ref:`multi-phase-initialization`. + It should not be used in other contexts. + + Note that Python assumes that ``PyModuleDef`` structures are statically + allocated. + This function may return either a new reference or a borrowed one; + this reference must not be released. + + .. versionadded:: 3.5 + + +.. _single-phase-initialization: + +Legacy single-phase initialization +.................................. + +.. attention:: + Single-phase initialization is a legacy mechanism to initialize extension + modules, with known drawbacks and design flaws. Extension module authors + are encouraged to use multi-phase initialization instead. + +In single-phase initialization, the +:ref:`initialization function <extension-export-hook>` (``PyInit_modulename``) +should create, populate and return a module object. +This is typically done using :c:func:`PyModule_Create` and functions like +:c:func:`PyModule_AddObjectRef`. + +Single-phase initialization differs from the :ref:`default <multi-phase-initialization>` +in the following ways: + +* Single-phase modules are, or rather *contain*, “singletons”. + + When the module is first initialized, Python saves the contents of + the module's ``__dict__`` (that is, typically, the module's functions and + types). + + For subsequent imports, Python does not call the initialization function + again. + Instead, it creates a new module object with a new ``__dict__``, and copies + the saved contents to it. + For example, given a single-phase module ``_testsinglephase`` + [#testsinglephase]_ that defines a function ``sum`` and an exception class + ``error``: + + .. code-block:: python + + >>> import sys + >>> import _testsinglephase as one + >>> del sys.modules['_testsinglephase'] + >>> import _testsinglephase as two + >>> one is two + False + >>> one.__dict__ is two.__dict__ + False + >>> one.sum is two.sum + True + >>> one.error is two.error + True + + The exact behavior should be considered a CPython implementation detail. + +* To work around the fact that ``PyInit_modulename`` does not take a *spec* + argument, some state of the import machinery is saved and applied to the + first suitable module created during the ``PyInit_modulename`` call. + Specifically, when a sub-module is imported, this mechanism prepends the + parent package name to the name of the module. + + A single-phase ``PyInit_modulename`` function should create “its” module + object as soon as possible, before any other module objects can be created. + +* Non-ASCII module names (``PyInitU_modulename``) are not supported. + +* Single-phase modules support module lookup functions like + :c:func:`PyState_FindModule`. + +.. [#testsinglephase] ``_testsinglephase`` is an internal module used \ + in CPython's self-test suite; your installation may or may not \ + include it. diff --git a/Doc/c-api/index.rst b/Doc/c-api/index.rst index ba56b03c6ac..e9df2a304d9 100644 --- a/Doc/c-api/index.rst +++ b/Doc/c-api/index.rst @@ -17,6 +17,7 @@ document the API functions in detail. veryhigh.rst refcounting.rst exceptions.rst + extension-modules.rst utilities.rst abstract.rst concrete.rst diff --git a/Doc/c-api/init.rst b/Doc/c-api/init.rst index 9c866438b48..3106bf9808f 100644 --- a/Doc/c-api/init.rst +++ b/Doc/c-api/init.rst @@ -492,17 +492,8 @@ Initializing and finalizing the interpreter strings other than those passed in (however, the contents of the strings pointed to by the argument list are not modified). - The return value will be ``0`` if the interpreter exits normally (i.e., - without an exception), ``1`` if the interpreter exits due to an exception, - or ``2`` if the argument list does not represent a valid Python command - line. - - Note that if an otherwise unhandled :exc:`SystemExit` is raised, this - function will not return ``1``, but exit the process, as long as - ``Py_InspectFlag`` is not set. If ``Py_InspectFlag`` is set, execution will - drop into the interactive Python prompt, at which point a second otherwise - unhandled :exc:`SystemExit` will still exit the process, while any other - means of exiting will set the return value as described above. + The return value is ``2`` if the argument list does not represent a valid + Python command line, and otherwise the same as :c:func:`Py_RunMain`. In terms of the CPython runtime configuration APIs documented in the :ref:`runtime configuration <init-config>` section (and without accounting @@ -539,23 +530,18 @@ Initializing and finalizing the interpreter If :c:member:`PyConfig.inspect` is not set (the default), the return value will be ``0`` if the interpreter exits normally (that is, without raising - an exception), or ``1`` if the interpreter exits due to an exception. If an - otherwise unhandled :exc:`SystemExit` is raised, the function will immediately - exit the process instead of returning ``1``. + an exception), the exit status of an unhandled :exc:`SystemExit`, or ``1`` + for any other unhandled exception. If :c:member:`PyConfig.inspect` is set (such as when the :option:`-i` option is used), rather than returning when the interpreter exits, execution will instead resume in an interactive Python prompt (REPL) using the ``__main__`` module's global namespace. If the interpreter exited with an exception, it is immediately raised in the REPL session. The function return value is - then determined by the way the *REPL session* terminates: returning ``0`` - if the session terminates without raising an unhandled exception, exiting - immediately for an unhandled :exc:`SystemExit`, and returning ``1`` for - any other unhandled exception. - - This function always finalizes the Python interpreter regardless of whether - it returns a value or immediately exits the process due to an unhandled - :exc:`SystemExit` exception. + then determined by the way the *REPL session* terminates: ``0``, ``1``, or + the status of a :exc:`SystemExit`, as specified above. + + This function always finalizes the Python interpreter before it returns. See :ref:`Python Configuration <init-python-config>` for an example of a customized Python that always runs in isolated mode using diff --git a/Doc/c-api/intro.rst b/Doc/c-api/intro.rst index 41856922110..acce3dc215d 100644 --- a/Doc/c-api/intro.rst +++ b/Doc/c-api/intro.rst @@ -111,33 +111,11 @@ Useful macros ============= Several useful macros are defined in the Python header files. Many are -defined closer to where they are useful (e.g. :c:macro:`Py_RETURN_NONE`). +defined closer to where they are useful (for example, :c:macro:`Py_RETURN_NONE`, +:c:macro:`PyMODINIT_FUNC`). Others of a more general utility are defined here. This is not necessarily a complete listing. -.. c:macro:: PyMODINIT_FUNC - - Declare an extension module ``PyInit`` initialization function. The function - return type is :c:expr:`PyObject*`. The macro declares any special linkage - declarations required by the platform, and for C++ declares the function as - ``extern "C"``. - - The initialization function must be named :samp:`PyInit_{name}`, where - *name* is the name of the module, and should be the only non-\ ``static`` - item defined in the module file. Example:: - - static struct PyModuleDef spam_module = { - .m_base = PyModuleDef_HEAD_INIT, - .m_name = "spam", - ... - }; - - PyMODINIT_FUNC - PyInit_spam(void) - { - return PyModuleDef_Init(&spam_module); - } - .. c:macro:: Py_ABS(x) diff --git a/Doc/c-api/module.rst b/Doc/c-api/module.rst index 710135dca89..c8edcecc5b4 100644 --- a/Doc/c-api/module.rst +++ b/Doc/c-api/module.rst @@ -127,25 +127,36 @@ Module Objects unencodable filenames, use :c:func:`PyModule_GetFilenameObject` instead. -.. _initializing-modules: +.. _pymoduledef: -Initializing C modules -^^^^^^^^^^^^^^^^^^^^^^ +Module definitions +------------------ -Modules objects are usually created from extension modules (shared libraries -which export an initialization function), or compiled-in modules -(where the initialization function is added using :c:func:`PyImport_AppendInittab`). -See :ref:`building` or :ref:`extending-with-embedding` for details. +The functions in the previous section work on any module object, including +modules imported from Python code. -The initialization function can either pass a module definition instance -to :c:func:`PyModule_Create`, and return the resulting module object, -or request "multi-phase initialization" by returning the definition struct itself. +Modules defined using the C API typically use a *module definition*, +:c:type:`PyModuleDef` -- a statically allocated, constant “description" of +how a module should be created. + +The definition is usually used to define an extension's “main” module object +(see :ref:`extension-modules` for details). +It is also used to +:ref:`create extension modules dynamically <moduledef-dynamic>`. + +Unlike :c:func:`PyModule_New`, the definition allows management of +*module state* -- a piece of memory that is allocated and cleared together +with the module object. +Unlike the module's Python attributes, Python code cannot replace or delete +data stored in module state. .. c:type:: PyModuleDef The module definition struct, which holds all information needed to create - a module object. There is usually only one statically initialized variable - of this type for each module. + a module object. + This structure must be statically allocated (or be otherwise guaranteed + to be valid while any modules created from it exist). + Usually, there is only one variable of this type for each extension module. .. c:member:: PyModuleDef_Base m_base @@ -170,13 +181,15 @@ or request "multi-phase initialization" by returning the definition struct itsel and freed when the module object is deallocated, after the :c:member:`~PyModuleDef.m_free` function has been called, if present. - Setting ``m_size`` to ``-1`` means that the module does not support - sub-interpreters, because it has global state. - Setting it to a non-negative value means that the module can be re-initialized and specifies the additional amount of memory it requires - for its state. Non-negative ``m_size`` is required for multi-phase - initialization. + for its state. + + Setting ``m_size`` to ``-1`` means that the module does not support + sub-interpreters, because it has global state. + Negative ``m_size`` is only allowed when using + :ref:`legacy single-phase initialization <single-phase-initialization>` + or when :ref:`creating modules dynamically <moduledef-dynamic>`. See :PEP:`3121` for more details. @@ -189,7 +202,7 @@ or request "multi-phase initialization" by returning the definition struct itsel An array of slot definitions for multi-phase initialization, terminated by a ``{0, NULL}`` entry. - When using single-phase initialization, *m_slots* must be ``NULL``. + When using legacy single-phase initialization, *m_slots* must be ``NULL``. .. versionchanged:: 3.5 @@ -249,96 +262,9 @@ or request "multi-phase initialization" by returning the definition struct itsel .. versionchanged:: 3.9 No longer called before the module state is allocated. -Single-phase initialization -........................... - -The module initialization function may create and return the module object -directly. This is referred to as "single-phase initialization", and uses one -of the following two module creation functions: - -.. c:function:: PyObject* PyModule_Create(PyModuleDef *def) - - Create a new module object, given the definition in *def*. This behaves - like :c:func:`PyModule_Create2` with *module_api_version* set to - :c:macro:`PYTHON_API_VERSION`. - - -.. c:function:: PyObject* PyModule_Create2(PyModuleDef *def, int module_api_version) - - Create a new module object, given the definition in *def*, assuming the - API version *module_api_version*. If that version does not match the version - of the running interpreter, a :exc:`RuntimeWarning` is emitted. - - Return ``NULL`` with an exception set on error. - - .. note:: - - Most uses of this function should be using :c:func:`PyModule_Create` - instead; only use this if you are sure you need it. -Before it is returned from in the initialization function, the resulting module -object is typically populated using functions like :c:func:`PyModule_AddObjectRef`. - -.. _multi-phase-initialization: - -Multi-phase initialization -.......................... - -An alternate way to specify extensions is to request "multi-phase initialization". -Extension modules created this way behave more like Python modules: the -initialization is split between the *creation phase*, when the module object -is created, and the *execution phase*, when it is populated. -The distinction is similar to the :py:meth:`~object.__new__` and -:py:meth:`~object.__init__` methods of classes. - -Unlike modules created using single-phase initialization, these modules are not -singletons. -For example, if the :py:attr:`sys.modules` entry is removed and the module -is re-imported, a new module object is created, and typically populated with -fresh method and type objects. -The old module is subject to normal garbage collection. -This mirrors the behavior of pure-Python modules. - -Additional module instances may be created in -:ref:`sub-interpreters <sub-interpreter-support>` -or after after Python runtime reinitialization -(:c:func:`Py_Finalize` and :c:func:`Py_Initialize`). -In these cases, sharing Python objects between module instances would likely -cause crashes or undefined behavior. - -To avoid such issues, each instance of an extension module should -be *isolated*: changes to one instance should not implicitly affect the others, -and all state, including references to Python objects, should be specific to -a particular module instance. -See :ref:`isolating-extensions-howto` for more details and a practical guide. - -A simpler way to avoid these issues is -:ref:`raising an error on repeated initialization <isolating-extensions-optout>`. - -All modules created using multi-phase initialization are expected to support -:ref:`sub-interpreters <sub-interpreter-support>`, or otherwise explicitly -signal a lack of support. -This is usually achieved by isolation or blocking repeated initialization, -as above. -A module may also be limited to the main interpreter using -the :c:data:`Py_mod_multiple_interpreters` slot. - -To request multi-phase initialization, the initialization function -(PyInit_modulename) returns a :c:type:`PyModuleDef` instance with non-empty -:c:member:`~PyModuleDef.m_slots`. Before it is returned, the ``PyModuleDef`` -instance must be initialized with the following function: - -.. c:function:: PyObject* PyModuleDef_Init(PyModuleDef *def) - - Ensures a module definition is a properly initialized Python object that - correctly reports its type and reference count. - - Returns *def* cast to ``PyObject*``, or ``NULL`` if an error occurred. - - .. versionadded:: 3.5 - -The *m_slots* member of the module definition must point to an array of -``PyModuleDef_Slot`` structures: +Module slots +............ .. c:type:: PyModuleDef_Slot @@ -352,8 +278,6 @@ The *m_slots* member of the module definition must point to an array of .. versionadded:: 3.5 -The *m_slots* array must be terminated by a slot with id 0. - The available slot types are: .. c:macro:: Py_mod_create @@ -464,21 +388,48 @@ The available slot types are: .. versionadded:: 3.13 -See :PEP:`489` for more details on multi-phase initialization. -Low-level module creation functions -................................... +.. _moduledef-dynamic: + +Creating extension modules dynamically +-------------------------------------- + +The following functions may be used to create a module outside of an +extension's :ref:`initialization function <extension-export-hook>`. +They are also used in +:ref:`single-phase initialization <single-phase-initialization>`. + +.. c:function:: PyObject* PyModule_Create(PyModuleDef *def) + + Create a new module object, given the definition in *def*. + This is a macro that calls :c:func:`PyModule_Create2` with + *module_api_version* set to :c:macro:`PYTHON_API_VERSION`, or + to :c:macro:`PYTHON_ABI_VERSION` if using the + :ref:`limited API <limited-c-api>`. + +.. c:function:: PyObject* PyModule_Create2(PyModuleDef *def, int module_api_version) + + Create a new module object, given the definition in *def*, assuming the + API version *module_api_version*. If that version does not match the version + of the running interpreter, a :exc:`RuntimeWarning` is emitted. + + Return ``NULL`` with an exception set on error. + + This function does not support slots. + The :c:member:`~PyModuleDef.m_slots` member of *def* must be ``NULL``. + -The following functions are called under the hood when using multi-phase -initialization. They can be used directly, for example when creating module -objects dynamically. Note that both ``PyModule_FromDefAndSpec`` and -``PyModule_ExecDef`` must be called to fully initialize a module. + .. note:: + + Most uses of this function should be using :c:func:`PyModule_Create` + instead; only use this if you are sure you need it. .. c:function:: PyObject * PyModule_FromDefAndSpec(PyModuleDef *def, PyObject *spec) - Create a new module object, given the definition in *def* and the - ModuleSpec *spec*. This behaves like :c:func:`PyModule_FromDefAndSpec2` - with *module_api_version* set to :c:macro:`PYTHON_API_VERSION`. + This macro calls :c:func:`PyModule_FromDefAndSpec2` with + *module_api_version* set to :c:macro:`PYTHON_API_VERSION`, or + to :c:macro:`PYTHON_ABI_VERSION` if using the + :ref:`limited API <limited-c-api>`. .. versionadded:: 3.5 @@ -491,6 +442,10 @@ objects dynamically. Note that both ``PyModule_FromDefAndSpec`` and Return ``NULL`` with an exception set on error. + Note that this does not process execution slots (:c:data:`Py_mod_exec`). + Both ``PyModule_FromDefAndSpec`` and ``PyModule_ExecDef`` must be called + to fully initialize a module. + .. note:: Most uses of this function should be using :c:func:`PyModule_FromDefAndSpec` @@ -504,35 +459,29 @@ objects dynamically. Note that both ``PyModule_FromDefAndSpec`` and .. versionadded:: 3.5 -.. c:function:: int PyModule_SetDocString(PyObject *module, const char *docstring) +.. c:macro:: PYTHON_API_VERSION - Set the docstring for *module* to *docstring*. - This function is called automatically when creating a module from - ``PyModuleDef``, using either ``PyModule_Create`` or - ``PyModule_FromDefAndSpec``. + The C API version. Defined for backwards compatibility. - .. versionadded:: 3.5 + Currently, this constant is not updated in new Python versions, and is not + useful for versioning. This may change in the future. -.. c:function:: int PyModule_AddFunctions(PyObject *module, PyMethodDef *functions) +.. c:macro:: PYTHON_ABI_VERSION - Add the functions from the ``NULL`` terminated *functions* array to *module*. - Refer to the :c:type:`PyMethodDef` documentation for details on individual - entries (due to the lack of a shared module namespace, module level - "functions" implemented in C typically receive the module as their first - parameter, making them similar to instance methods on Python classes). - This function is called automatically when creating a module from - ``PyModuleDef``, using either ``PyModule_Create`` or - ``PyModule_FromDefAndSpec``. + Defined as ``3`` for backwards compatibility. + + Currently, this constant is not updated in new Python versions, and is not + useful for versioning. This may change in the future. - .. versionadded:: 3.5 Support functions -................. +----------------- -The module initialization function (if using single phase initialization) or -a function called from a module execution slot (if using multi-phase -initialization), can use the following functions to help initialize the module -state: +The following functions are provided to help initialize a module +state. +They are intended for a module's execution slots (:c:data:`Py_mod_exec`), +the initialization function for legacy :ref:`single-phase initialization <single-phase-initialization>`, +or code that creates modules dynamically. .. c:function:: int PyModule_AddObjectRef(PyObject *module, const char *name, PyObject *value) @@ -681,12 +630,39 @@ state: .. versionadded:: 3.9 +.. c:function:: int PyModule_AddFunctions(PyObject *module, PyMethodDef *functions) + + Add the functions from the ``NULL`` terminated *functions* array to *module*. + Refer to the :c:type:`PyMethodDef` documentation for details on individual + entries (due to the lack of a shared module namespace, module level + "functions" implemented in C typically receive the module as their first + parameter, making them similar to instance methods on Python classes). + + This function is called automatically when creating a module from + ``PyModuleDef`` (such as when using :ref:`multi-phase-initialization`, + ``PyModule_Create``, or ``PyModule_FromDefAndSpec``). + Some module authors may prefer defining functions in multiple + :c:type:`PyMethodDef` arrays; in that case they should call this function + directly. + + .. versionadded:: 3.5 + +.. c:function:: int PyModule_SetDocString(PyObject *module, const char *docstring) + + Set the docstring for *module* to *docstring*. + This function is called automatically when creating a module from + ``PyModuleDef`` (such as when using :ref:`multi-phase-initialization`, + ``PyModule_Create``, or ``PyModule_FromDefAndSpec``). + + .. versionadded:: 3.5 + .. c:function:: int PyUnstable_Module_SetGIL(PyObject *module, void *gil) Indicate that *module* does or does not support running without the global interpreter lock (GIL), using one of the values from :c:macro:`Py_mod_gil`. It must be called during *module*'s initialization - function. If this function is not called during module initialization, the + function when using :ref:`single-phase-initialization`. + If this function is not called during module initialization, the import machinery assumes the module does not support running without the GIL. This function is only available in Python builds configured with :option:`--disable-gil`. @@ -695,10 +671,11 @@ state: .. versionadded:: 3.13 -Module lookup -^^^^^^^^^^^^^ +Module lookup (single-phase initialization) +........................................... -Single-phase initialization creates singleton modules that can be looked up +The legacy :ref:`single-phase initialization <single-phase-initialization>` +initialization scheme creates singleton modules that can be looked up in the context of the current interpreter. This allows the module object to be retrieved later with only a reference to the module definition. @@ -719,7 +696,8 @@ since multiple such modules can be created from a single definition. Only effective on modules created using single-phase initialization. - Python calls ``PyState_AddModule`` automatically after importing a module, + Python calls ``PyState_AddModule`` automatically after importing a module + that uses :ref:`single-phase initialization <single-phase-initialization>`, so it is unnecessary (but harmless) to call it from module initialization code. An explicit call is needed only if the module's own init code subsequently calls ``PyState_FindModule``. @@ -727,6 +705,9 @@ since multiple such modules can be created from a single definition. mechanisms (either by calling it directly, or by referring to its implementation for details of the required state updates). + If a module was attached previously using the same *def*, it is replaced + by the new *module*. + The caller must have an :term:`attached thread state`. Return ``-1`` with an exception set on error, ``0`` on success. diff --git a/Doc/data/refcounts.dat b/Doc/data/refcounts.dat index 59b31ccf7bc..f5f02f0a79c 100644 --- a/Doc/data/refcounts.dat +++ b/Doc/data/refcounts.dat @@ -1489,9 +1489,6 @@ PyModule_SetDocString:int::: PyModule_SetDocString:PyObject*:module:0: PyModule_SetDocString:const char*:docstring:: -PyModuleDef_Init:PyObject*::0: -PyModuleDef_Init:PyModuleDef*:def:: - PyNumber_Absolute:PyObject*::+1: PyNumber_Absolute:PyObject*:o:0: diff --git a/Doc/extending/building.rst b/Doc/extending/building.rst index a58eb40d431..098dde39ea5 100644 --- a/Doc/extending/building.rst +++ b/Doc/extending/building.rst @@ -6,41 +6,10 @@ Building C and C++ Extensions ***************************** -A C extension for CPython is a shared library (e.g. a ``.so`` file on Linux, -``.pyd`` on Windows), which exports an *initialization function*. +A C extension for CPython is a shared library (for example, a ``.so`` file on +Linux, ``.pyd`` on Windows), which exports an *initialization function*. -To be importable, the shared library must be available on :envvar:`PYTHONPATH`, -and must be named after the module name, with an appropriate extension. -When using setuptools, the correct filename is generated automatically. - -The initialization function has the signature: - -.. c:function:: PyObject* PyInit_modulename(void) - -It returns either a fully initialized module, or a :c:type:`PyModuleDef` -instance. See :ref:`initializing-modules` for details. - -.. highlight:: python - -For modules with ASCII-only names, the function must be named -:samp:`PyInit_{<name>}`, with ``<name>`` replaced by the name of the module. -When using :ref:`multi-phase-initialization`, non-ASCII module names -are allowed. In this case, the initialization function name is -:samp:`PyInitU_{<name>}`, with ``<name>`` encoded using Python's -*punycode* encoding with hyphens replaced by underscores. In Python:: - - def initfunc_name(name): - try: - suffix = b'_' + name.encode('ascii') - except UnicodeEncodeError: - suffix = b'U_' + name.encode('punycode').replace(b'-', b'_') - return b'PyInit' + suffix - -It is possible to export multiple modules from a single shared library by -defining multiple initialization functions. However, importing them requires -using symbolic links or a custom importer, because by default only the -function corresponding to the filename is found. -See the *"Multiple modules in one library"* section in :pep:`489` for details. +See :ref:`extension-modules` for details. .. highlight:: c @@ -51,7 +20,11 @@ See the *"Multiple modules in one library"* section in :pep:`489` for details. Building C and C++ Extensions with setuptools ============================================= -Python 3.12 and newer no longer come with distutils. Please refer to the -``setuptools`` documentation at -https://setuptools.readthedocs.io/en/latest/setuptools.html -to learn more about how build and distribute C/C++ extensions with setuptools. + +Building, packaging and distributing extension modules is best done with +third-party tools, and is out of scope of this document. +One suitable tool is Setuptools, whose documentation can be found at +https://setuptools.pypa.io/en/latest/setuptools.html. + +The :mod:`distutils` module, which was included in the standard library +until Python 3.12, is now maintained as part of Setuptools. diff --git a/Doc/howto/perf_profiling.rst b/Doc/howto/perf_profiling.rst index b579d776576..96d757ac452 100644 --- a/Doc/howto/perf_profiling.rst +++ b/Doc/howto/perf_profiling.rst @@ -92,7 +92,7 @@ Then we can use ``perf report`` to analyze the data: | | | | | | | |--51.67%--_PyEval_EvalFrameDefault | | | | | - | | | | |--11.52%--_PyLong_Add + | | | | |--11.52%--_PyCompactLong_Add | | | | | | | | | | | |--2.97%--_PyObject_Malloc ... @@ -142,7 +142,7 @@ Instead, if we run the same experiment with ``perf`` support enabled we get: | | | | | | | |--51.81%--_PyEval_EvalFrameDefault | | | | | - | | | | |--13.77%--_PyLong_Add + | | | | |--13.77%--_PyCompactLong_Add | | | | | | | | | | | |--3.26%--_PyObject_Malloc diff --git a/Doc/library/concurrency.rst b/Doc/library/concurrency.rst index 5be1a1106b0..18f9443cbfe 100644 --- a/Doc/library/concurrency.rst +++ b/Doc/library/concurrency.rst @@ -18,6 +18,7 @@ multitasking). Here's an overview: multiprocessing.shared_memory.rst concurrent.rst concurrent.futures.rst + concurrent.interpreters.rst subprocess.rst sched.rst queue.rst diff --git a/Doc/library/concurrent.interpreters.rst b/Doc/library/concurrent.interpreters.rst new file mode 100644 index 00000000000..8860418e87a --- /dev/null +++ b/Doc/library/concurrent.interpreters.rst @@ -0,0 +1,198 @@ +:mod:`!concurrent.interpreters` --- Multiple interpreters in the same process +============================================================================= + +.. module:: concurrent.interpreters + :synopsis: Multiple interpreters in the same process + +.. moduleauthor:: Eric Snow <ericsnowcurrently@gmail.com> +.. sectionauthor:: Eric Snow <ericsnowcurrently@gmail.com> + +.. versionadded:: 3.14 + +**Source code:** :source:`Lib/concurrent/interpreters.py` + +-------------- + + +Introduction +------------ + +The :mod:`!concurrent.interpreters` module constructs higher-level +interfaces on top of the lower level :mod:`!_interpreters` module. + +.. XXX Add references to the upcoming HOWTO docs in the seealso block. + +.. seealso:: + + :ref:`isolating-extensions-howto` + how to update an extension module to support multiple interpreters + + :pep:`554` + + :pep:`734` + + :pep:`684` + +.. XXX Why do we disallow multiple interpreters on WASM? + +.. include:: ../includes/wasm-notavail.rst + + +Key details +----------- + +Before we dive into examples, there are a small number of details +to keep in mind about using multiple interpreters: + +* isolated, by default +* no implicit threads +* not all PyPI packages support use in multiple interpreters yet + +.. XXX Are there other relevant details to list? + +In the context of multiple interpreters, "isolated" means that +different interpreters do not share any state. In practice, there is some +process-global data they all share, but that is managed by the runtime. + + +Reference +--------- + +This module defines the following functions: + +.. function:: list_all() + + Return a :class:`list` of :class:`Interpreter` objects, + one for each existing interpreter. + +.. function:: get_current() + + Return an :class:`Interpreter` object for the currently running + interpreter. + +.. function:: get_main() + + Return an :class:`Interpreter` object for the main interpreter. + +.. function:: create() + + Initialize a new (idle) Python interpreter + and return a :class:`Interpreter` object for it. + + +Interpreter objects +^^^^^^^^^^^^^^^^^^^ + +.. class:: Interpreter(id) + + A single interpreter in the current process. + + Generally, :class:`Interpreter` shouldn't be called directly. + Instead, use :func:`create` or one of the other module functions. + + .. attribute:: id + + (read-only) + + The interpreter's ID. + + .. attribute:: whence + + (read-only) + + A string describing where the interpreter came from. + + .. method:: is_running() + + Return ``True`` if the interpreter is currently executing code + in its :mod:`!__main__` module and ``False`` otherwise. + + .. method:: close() + + Finalize and destroy the interpreter. + + .. method:: prepare_main(ns=None, **kwargs) + + Bind "shareable" objects in the interpreter's + :mod:`!__main__` module. + + .. method:: exec(code, /, dedent=True) + + Run the given source code in the interpreter (in the current thread). + + .. method:: call(callable, /, *args, **kwargs) + + Return the result of calling running the given function in the + interpreter (in the current thread). + + .. method:: call_in_thread(callable, /, *args, **kwargs) + + Run the given function in the interpreter (in a new thread). + +Exceptions +^^^^^^^^^^ + +.. exception:: InterpreterError + + This exception, a subclass of :exc:`Exception`, is raised when + an interpreter-related error happens. + +.. exception:: InterpreterNotFoundError + + This exception, a subclass of :exc:`InterpreterError`, is raised when + the targeted interpreter no longer exists. + +.. exception:: ExecutionFailed + + This exception, a subclass of :exc:`InterpreterError`, is raised when + the running code raised an uncaught exception. + + .. attribute:: excinfo + + A basic snapshot of the exception raised in the other interpreter. + +.. XXX Document the excinfoattrs? + +.. exception:: NotShareableError + + This exception, a subclass of :exc:`TypeError`, is raised when + an object cannot be sent to another interpreter. + + +.. XXX Add functions for communicating between interpreters. + + +Basic usage +----------- + +Creating an interpreter and running code in it:: + + from concurrent import interpreters + + interp = interpreters.create() + + # Run in the current OS thread. + + interp.exec('print("spam!")') + + interp.exec("""if True: + print('spam!') + """) + + from textwrap import dedent + interp.exec(dedent(""" + print('spam!') + """)) + + def run(): + print('spam!') + + interp.call(run) + + # Run in new OS thread. + + t = interp.call_in_thread(run) + t.join() + + +.. XXX Explain about object "sharing". diff --git a/Doc/library/concurrent.rst b/Doc/library/concurrent.rst index 8caea78bbb5..748c72c733b 100644 --- a/Doc/library/concurrent.rst +++ b/Doc/library/concurrent.rst @@ -1,6 +1,7 @@ The :mod:`!concurrent` package ============================== -Currently, there is only one module in this package: +This package contains the following modules: * :mod:`concurrent.futures` -- Launching parallel tasks +* :mod:`concurrent.interpreters` -- Multiple interpreters in the same process diff --git a/Doc/library/dataclasses.rst b/Doc/library/dataclasses.rst index f18c7cc9c02..299c8aa399c 100644 --- a/Doc/library/dataclasses.rst +++ b/Doc/library/dataclasses.rst @@ -121,8 +121,11 @@ Module contents :meth:`!__le__`, :meth:`!__gt__`, or :meth:`!__ge__`, then :exc:`TypeError` is raised. - - *unsafe_hash*: If ``False`` (the default), a :meth:`~object.__hash__` method - is generated according to how *eq* and *frozen* are set. + - *unsafe_hash*: If true, force ``dataclasses`` to create a + :meth:`~object.__hash__` method, even though it may not be safe to do so. + Otherwise, generate a :meth:`~object.__hash__` method according to how + *eq* and *frozen* are set. + The default value is ``False``. :meth:`!__hash__` is used by built-in :meth:`hash`, and when objects are added to hashed collections such as dictionaries and sets. Having a diff --git a/Doc/library/email.header.rst b/Doc/library/email.header.rst index 219fad0d2f6..c3392a62b8e 100644 --- a/Doc/library/email.header.rst +++ b/Doc/library/email.header.rst @@ -178,16 +178,36 @@ The :mod:`email.header` module also provides the following convenient functions. Decode a message header value without converting the character set. The header value is in *header*. - This function returns a list of ``(decoded_string, charset)`` pairs containing - each of the decoded parts of the header. *charset* is ``None`` for non-encoded - parts of the header, otherwise a lower case string containing the name of the - character set specified in the encoded string. + For historical reasons, this function may return either: - Here's an example:: + 1. A list of pairs containing each of the decoded parts of the header, + ``(decoded_bytes, charset)``, where *decoded_bytes* is always an instance of + :class:`bytes`, and *charset* is either: + + - A lower case string containing the name of the character set specified. + + - ``None`` for non-encoded parts of the header. + + 2. A list of length 1 containing a pair ``(string, None)``, where + *string* is always an instance of :class:`str`. + + An :exc:`email.errors.HeaderParseError` may be raised when certain decoding + errors occur (e.g. a base64 decoding exception). + + Here are examples: >>> from email.header import decode_header >>> decode_header('=?iso-8859-1?q?p=F6stal?=') [(b'p\xf6stal', 'iso-8859-1')] + >>> decode_header('unencoded_string') + [('unencoded_string', None)] + >>> decode_header('bar =?utf-8?B?ZsOzbw==?=') + [(b'bar ', None), (b'f\xc3\xb3o', 'utf-8')] + + .. note:: + + This function exists for for backwards compatibility only. For + new code, we recommend using :class:`email.headerregistry.HeaderRegistry`. .. function:: make_header(decoded_seq, maxlinelen=None, header_name=None, continuation_ws=' ') @@ -203,3 +223,7 @@ The :mod:`email.header` module also provides the following convenient functions. :class:`Header` instance. Optional *maxlinelen*, *header_name*, and *continuation_ws* are as in the :class:`Header` constructor. + .. note:: + + This function exists for for backwards compatibility only, and is + not recommended for use in new code. diff --git a/Doc/library/logging.config.rst b/Doc/library/logging.config.rst index 0e9dc33ae21..f8c71005a53 100644 --- a/Doc/library/logging.config.rst +++ b/Doc/library/logging.config.rst @@ -548,7 +548,7 @@ mnemonic that the corresponding value is a callable. The ``filters`` member of ``handlers`` and ``loggers`` can take filter instances in addition to ids. -You can also specify a special key ``'.'`` whose value is a dictionary is a +You can also specify a special key ``'.'`` whose value is a mapping of attribute names to values. If found, the specified attributes will be set on the user-defined object before it is returned. Thus, with the following configuration:: diff --git a/Doc/library/math.rst b/Doc/library/math.rst index c8061fb1638..ecb1d4102ca 100644 --- a/Doc/library/math.rst +++ b/Doc/library/math.rst @@ -387,8 +387,8 @@ Floating point manipulation functions .. function:: issubnormal(x) Return ``True`` if *x* is a subnormal number, that is a finite - nonzero number with a magnitude smaller than the smallest positive normal - number, see :data:`sys.float_info.min`. Return ``False`` otherwise. + nonzero number with a magnitude smaller than :data:`sys.float_info.min`. + Return ``False`` otherwise. .. versionadded:: next diff --git a/Doc/library/python.rst b/Doc/library/python.rst index c2c231af7c3..c5c762e11b9 100644 --- a/Doc/library/python.rst +++ b/Doc/library/python.rst @@ -27,3 +27,8 @@ overview: inspect.rst annotationlib.rst site.rst + +.. seealso:: + + * See the :mod:`concurrent.interpreters` module, which similarly + exposes core runtime functionality. diff --git a/Doc/library/stdtypes.rst b/Doc/library/stdtypes.rst index b75e5ceecf8..394c302fd35 100644 --- a/Doc/library/stdtypes.rst +++ b/Doc/library/stdtypes.rst @@ -1841,6 +1841,14 @@ expression support in the :mod:`re` module). unless an encoding error actually occurs, :ref:`devmode` is enabled or a :ref:`debug build <debug-build>` is used. + For example:: + + >>> encoded_str_to_bytes = 'Python'.encode() + >>> type(encoded_str_to_bytes) + <class 'bytes'> + >>> encoded_str_to_bytes + b'Python' + .. versionchanged:: 3.1 Added support for keyword arguments. @@ -1855,7 +1863,19 @@ expression support in the :mod:`re` module). Return ``True`` if the string ends with the specified *suffix*, otherwise return ``False``. *suffix* can also be a tuple of suffixes to look for. With optional *start*, test beginning at that position. With optional *end*, stop comparing - at that position. + at that position. Using *start* and *end* is equivalent to + ``str[start:end].endswith(suffix)``. For example:: + + >>> 'Python'.endswith('on') + True + >>> 'a tuple of suffixes'.endswith(('at', 'in')) + False + >>> 'a tuple of suffixes'.endswith(('at', 'es')) + True + >>> 'Python is amazing'.endswith('is', 0, 9) + True + + See also :meth:`startswith` and :meth:`removesuffix`. .. method:: str.expandtabs(tabsize=8) @@ -1871,12 +1891,15 @@ expression support in the :mod:`re` module). (``\n``) or return (``\r``), it is copied and the current column is reset to zero. Any other character is copied unchanged and the current column is incremented by one regardless of how the character is represented when - printed. + printed. For example:: >>> '01\t012\t0123\t01234'.expandtabs() '01 012 0123 01234' >>> '01\t012\t0123\t01234'.expandtabs(4) '01 012 0123 01234' + >>> print('01\t012\n0123\t01234'.expandtabs(4)) + 01 012 + 0123 01234 .. method:: str.find(sub[, start[, end]]) diff --git a/Doc/library/sys.rst b/Doc/library/sys.rst index 55e442b20ff..71f9999464a 100644 --- a/Doc/library/sys.rst +++ b/Doc/library/sys.rst @@ -1933,6 +1933,13 @@ always available. Unless explicitly noted otherwise, all variables are read-only interpreter is pre-release (alpha, beta, or release candidate) then the local and remote interpreters must be the same exact version. + .. audit-event:: remote_debugger_script script_path + + When the script is executed in the remote process, an + :ref:`auditing event <auditing>` + ``sys.remote_debugger_script`` is raised + with the path in the remote process. + .. availability:: Unix, Windows. .. versionadded:: 3.14 diff --git a/Doc/library/uuid.rst b/Doc/library/uuid.rst index 747ee3ee0e1..92d58024e84 100644 --- a/Doc/library/uuid.rst +++ b/Doc/library/uuid.rst @@ -257,7 +257,7 @@ The :mod:`uuid` module defines the following functions: non-specified arguments are substituted for a pseudo-random integer of appropriate size. - By default, *a*, *b* and *c* are generated by a non-cryptographically + By default, *a*, *b* and *c* are not generated by a cryptographically secure pseudo-random number generator (CSPRNG). Use :func:`uuid4` when a UUID needs to be used in a security-sensitive context. diff --git a/Doc/reference/expressions.rst b/Doc/reference/expressions.rst index 2a550b504ca..3d3bf1d9840 100644 --- a/Doc/reference/expressions.rst +++ b/Doc/reference/expressions.rst @@ -406,8 +406,9 @@ brackets or curly braces. Variables used in the generator expression are evaluated lazily when the :meth:`~generator.__next__` method is called for the generator object (in the same fashion as normal generators). However, the iterable expression in the -leftmost :keyword:`!for` clause is immediately evaluated, so that an error -produced by it will be emitted at the point where the generator expression +leftmost :keyword:`!for` clause is immediately evaluated, and the +:term:`iterator` is immediately created for that iterable, so that an error +produced while creating the iterator will be emitted at the point where the generator expression is defined, rather than at the point where the first value is retrieved. Subsequent :keyword:`!for` clauses and any filter condition in the leftmost :keyword:`!for` clause cannot be evaluated in the enclosing scope as they may diff --git a/Doc/using/configure.rst b/Doc/using/configure.rst index b914d3397b6..0b7eaf35a1e 100644 --- a/Doc/using/configure.rst +++ b/Doc/using/configure.rst @@ -445,6 +445,14 @@ Options for third-party dependencies C compiler and linker flags for ``libuuid``, used by :mod:`uuid` module, overriding ``pkg-config``. +.. option:: LIBZSTD_CFLAGS +.. option:: LIBZSTD_LIBS + + C compiler and linker flags for ``libzstd``, used by :mod:`compression.zstd` module, + overriding ``pkg-config``. + + .. versionadded:: 3.14 + .. option:: PANEL_CFLAGS .. option:: PANEL_LIBS diff --git a/Doc/whatsnew/3.14.rst b/Doc/whatsnew/3.14.rst index 45e68aea5fb..895446e2721 100644 --- a/Doc/whatsnew/3.14.rst +++ b/Doc/whatsnew/3.14.rst @@ -83,6 +83,7 @@ and improvements in user-friendliness and correctness. .. PEP-sized items next. * :ref:`PEP 649 and 749: deferred evaluation of annotations <whatsnew314-pep649>` +* :ref:`PEP 734: Multiple Interpreters in the Stdlib <whatsnew314-pep734>` * :ref:`PEP 741: Python Configuration C API <whatsnew314-pep741>` * :ref:`PEP 750: Template strings <whatsnew314-pep750>` * :ref:`PEP 758: Allow except and except* expressions without parentheses <whatsnew314-pep758>` @@ -123,6 +124,101 @@ of Python. See :ref:`below <whatsnew314-refcount>` for details. New features ============ +.. _whatsnew314-pep734: + +PEP 734: Multiple Interpreters in the Stdlib +-------------------------------------------- + +The CPython runtime supports running multiple copies of Python in the +same process simultaneously and has done so for over 20 years. +Each of these separate copies is called an "interpreter". +However, the feature had been available only through the C-API. + +That limitation is removed in the 3.14 release, +with the new :mod:`concurrent.interpreters` module. + +There are at least two notable reasons why using multiple interpreters +is worth considering: + +* they support a new (to Python), human-friendly concurrency model +* true multi-core parallelism + +For some use cases, concurrency in software enables efficiency and +can simplify software, at a high level. At the same time, implementing +and maintaining all but the simplest concurrency is often a struggle +for the human brain. That especially applies to plain threads +(for example, :mod:`threading`), where all memory is shared between all threads. + +With multiple isolated interpreters, you can take advantage of a class +of concurrency models, like CSP or the actor model, that have found +success in other programming languages, like Smalltalk, Erlang, +Haskell, and Go. Think of multiple interpreters like threads +but with opt-in sharing. + +Regarding multi-core parallelism: as of the 3.12 release, interpreters +are now sufficiently isolated from one another to be used in parallel. +(See :pep:`684`.) This unlocks a variety of CPU-intensive use cases +for Python that were limited by the :term:`GIL`. + +Using multiple interpreters is similar in many ways to +:mod:`multiprocessing`, in that they both provide isolated logical +"processes" that can run in parallel, with no sharing by default. +However, when using multiple interpreters, an application will use +fewer system resources and will operate more efficiently (since it +stays within the same process). Think of multiple interpreters as +having the isolation of processes with the efficiency of threads. + +.. XXX Add an example or two. +.. XXX Link to the not-yet-added HOWTO doc. + +While the feature has been around for decades, multiple interpreters +have not been used widely, due to low awareness and the lack of a stdlib +module. Consequently, they currently have several notable limitations, +which will improve significantly now that the feature is finally +going mainstream. + +Current limitations: + +* starting each interpreter has not been optimized yet +* each interpreter uses more memory than necessary + (we will be working next on extensive internal sharing between + interpreters) +* there aren't many options *yet* for truly sharing objects or other + data between interpreters (other than :type:`memoryview`) +* many extension modules on PyPI are not compatible with multiple + interpreters yet (stdlib extension modules *are* compatible) +* the approach to writing applications that use multiple isolated + interpreters is mostly unfamiliar to Python users, for now + +The impact of these limitations will depend on future CPython +improvements, how interpreters are used, and what the community solves +through PyPI packages. Depending on the use case, the limitations may +not have much impact, so try it out! + +Furthermore, future CPython releases will reduce or eliminate overhead +and provide utilities that are less appropriate on PyPI. In the +meantime, most of the limitations can also be addressed through +extension modules, meaning PyPI packages can fill any gap for 3.14, and +even back to 3.12 where interpreters were finally properly isolated and +stopped sharing the :term:`GIL`. Likewise, we expect to slowly see +libraries on PyPI for high-level abstractions on top of interpreters. + +Regarding extension modules, work is in progress to update some PyPI +projects, as well as tools like Cython, pybind11, nanobind, and PyO3. +The steps for isolating an extension module are found at +:ref:`isolating-extensions-howto`. Isolating a module has a lot of +overlap with what is required to support +:ref:`free-threading <whatsnew314-free-threaded-cpython>`, +so the ongoing work in the community in that area will help accelerate +support for multiple interpreters. + +Also added in 3.14: :ref:`concurrent.futures.InterpreterPoolExecutor +<whatsnew314-concurrent-futures-interp-pool>`. + +.. seealso:: + :pep:`734`. + + .. _whatsnew314-pep750: PEP 750: Template strings @@ -720,43 +816,58 @@ Executing the new tool on the running process will yield a table like this: python -m asyncio ps 12345 - tid task id task name coroutine chain awaiter name awaiter id - --------------------------------------------------------------------------------------------------------------------------------------- - 8138752 0x564bd3d0210 Task-1 0x0 - 8138752 0x564bd3d0410 Sundowning _aexit -> __aexit__ -> main Task-1 0x564bd3d0210 - 8138752 0x564bd3d0610 TMBTE _aexit -> __aexit__ -> main Task-1 0x564bd3d0210 - 8138752 0x564bd3d0810 TNDNBTG _aexit -> __aexit__ -> album Sundowning 0x564bd3d0410 - 8138752 0x564bd3d0a10 Levitate _aexit -> __aexit__ -> album Sundowning 0x564bd3d0410 - 8138752 0x564bd3e0550 DYWTYLM _aexit -> __aexit__ -> album TMBTE 0x564bd3d0610 - 8138752 0x564bd3e0710 Aqua Regia _aexit -> __aexit__ -> album TMBTE 0x564bd3d0610 + tid task id task name coroutine stack awaiter chain awaiter name awaiter id + ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ + 1935500 0x7fc930c18050 Task-1 TaskGroup._aexit -> TaskGroup.__aexit__ -> main 0x0 + 1935500 0x7fc930c18230 Sundowning TaskGroup._aexit -> TaskGroup.__aexit__ -> album TaskGroup._aexit -> TaskGroup.__aexit__ -> main Task-1 0x7fc930c18050 + 1935500 0x7fc93173fa50 TMBTE TaskGroup._aexit -> TaskGroup.__aexit__ -> album TaskGroup._aexit -> TaskGroup.__aexit__ -> main Task-1 0x7fc930c18050 + 1935500 0x7fc93173fdf0 TNDNBTG sleep -> play TaskGroup._aexit -> TaskGroup.__aexit__ -> album Sundowning 0x7fc930c18230 + 1935500 0x7fc930d32510 Levitate sleep -> play TaskGroup._aexit -> TaskGroup.__aexit__ -> album Sundowning 0x7fc930c18230 + 1935500 0x7fc930d32890 DYWTYLM sleep -> play TaskGroup._aexit -> TaskGroup.__aexit__ -> album TMBTE 0x7fc93173fa50 + 1935500 0x7fc93161ec30 Aqua Regia sleep -> play TaskGroup._aexit -> TaskGroup.__aexit__ -> album TMBTE 0x7fc93173fa50 - -or: +or a tree like this: .. code-block:: bash python -m asyncio pstree 12345 └── (T) Task-1 - └── main - └── __aexit__ - └── _aexit + └── main example.py:13 + └── TaskGroup.__aexit__ Lib/asyncio/taskgroups.py:72 + └── TaskGroup._aexit Lib/asyncio/taskgroups.py:121 ├── (T) Sundowning - │ └── album - │ └── __aexit__ - │ └── _aexit + │ └── album example.py:8 + │ └── TaskGroup.__aexit__ Lib/asyncio/taskgroups.py:72 + │ └── TaskGroup._aexit Lib/asyncio/taskgroups.py:121 │ ├── (T) TNDNBTG + │ │ └── play example.py:4 + │ │ └── sleep Lib/asyncio/tasks.py:702 │ └── (T) Levitate + │ └── play example.py:4 + │ └── sleep Lib/asyncio/tasks.py:702 └── (T) TMBTE - └── album - └── __aexit__ - └── _aexit + └── album example.py:8 + └── TaskGroup.__aexit__ Lib/asyncio/taskgroups.py:72 + └── TaskGroup._aexit Lib/asyncio/taskgroups.py:121 ├── (T) DYWTYLM + │ └── play example.py:4 + │ └── sleep Lib/asyncio/tasks.py:702 └── (T) Aqua Regia + └── play example.py:4 + └── sleep Lib/asyncio/tasks.py:702 If a cycle is detected in the async await graph (which could indicate a programming issue), the tool raises an error and lists the cycle paths that -prevent tree construction. +prevent tree construction: + +.. code-block:: bash + + python -m asyncio pstree 12345 + + ERROR: await-graph contains cycles - cannot print a tree! + + cycle: Task-2 → Task-3 → Task-2 (Contributed by Pablo Galindo, Łukasz Langa, Yury Selivanov, and Marta Gomez Macias in :gh:`91048`.) @@ -1109,6 +1220,8 @@ calendar concurrent.futures ------------------ +.. _whatsnew314-concurrent-futures-interp-pool: + * Add :class:`~concurrent.futures.InterpreterPoolExecutor`, which exposes "subinterpreters" (multiple Python interpreters in the same process) to Python code. This is separate from the proposed API @@ -1146,6 +1259,14 @@ concurrent.futures buffer. (Contributed by Enzo Bonnal and Josh Rosenberg in :gh:`74028`.) +configparser +------------ + +* Security fix: will no longer write config files it cannot read. Attempting + to :meth:`configparser.ConfigParser.write` keys containing delimiters or + beginning with the section header pattern will raise a + :class:`configparser.InvalidWriteError`. + (Contributed by Jacob Lincoln in :gh:`129270`) contextvars ----------- diff --git a/Doc/whatsnew/3.15.rst b/Doc/whatsnew/3.15.rst index 88e7462f688..9f327cf904d 100644 --- a/Doc/whatsnew/3.15.rst +++ b/Doc/whatsnew/3.15.rst @@ -134,6 +134,13 @@ shelve (Contributed by Andrea Oliveri in :gh:`134004`.) +sqlite3 +------- + +* Support SQL keyword completion in the :mod:`sqlite3` command-line interface. + (Contributed by Long Tan in :gh:`133393`.) + + ssl --- |