Reserved for various implementation-specific options. CPython currently
defines the following possible values:
- * ``-X faulthandler`` to enable :mod:`faulthandler`;
+ * ``-X faulthandler`` to enable :mod:`faulthandler`.
+ See also :envvar:`PYTHONFAULTHANDLER`.
* ``-X showrefcount`` to output the total reference count and number of used
memory blocks when the program finishes or after each statement in the
interactive interpreter. This only works on :ref:`debug builds
* ``-X tracemalloc`` to start tracing Python memory allocations using the
:mod:`tracemalloc` module. By default, only the most recent frame is
stored in a traceback of a trace. Use ``-X tracemalloc=NFRAME`` to start
- tracing with a traceback limit of *NFRAME* frames. See the
- :func:`tracemalloc.start` for more information.
+ tracing with a traceback limit of *NFRAME* frames.
+ See :func:`tracemalloc.start` and :envvar:`PYTHONTRACEMALLOC`
+ for more information.
* ``-X int_max_str_digits`` configures the :ref:`integer string conversion
length limitation <int_max_str_digits>`. See also
:envvar:`PYTHONINTMAXSTRDIGITS`.
* ``-X utf8`` enables the :ref:`Python UTF-8 Mode <utf8-mode>`.
``-X utf8=0`` explicitly disables :ref:`Python UTF-8 Mode <utf8-mode>`
(even when it would otherwise activate automatically).
+ See also :envvar:`PYTHONUTF8`.
* ``-X pycache_prefix=PATH`` enables writing ``.pyc`` files to a parallel
tree rooted at the given directory instead of to the code tree. See also
:envvar:`PYTHONPYCACHEPREFIX`.
Python memory allocations using the :mod:`tracemalloc` module. The value of
the variable is the maximum number of frames stored in a traceback of a
trace. For example, ``PYTHONTRACEMALLOC=1`` stores only the most recent
- frame. See the :func:`tracemalloc.start` for more information.
+ frame.
+ See the :func:`tracemalloc.start` function for more information.
+ This is equivalent to setting the :option:`-X` ``tracemalloc`` option.
.. versionadded:: 3.4
.. envvar:: PYTHONPROFILEIMPORTTIME
If this environment variable is set to a non-empty string, Python will
- show how long each import takes. This is exactly equivalent to setting
- ``-X importtime`` on the command line.
+ show how long each import takes.
+ This is equivalent to setting the :option:`-X` ``importtime`` option.
.. versionadded:: 3.7
If this environment variable is set to a non-empty string, enable
:ref:`Python Development Mode <devmode>`, introducing additional runtime
checks that are too expensive to be enabled by default.
+ This is equivalent to setting the :option:`-X` ``dev`` option.
.. versionadded:: 3.7