======================
WSGIDestroyInterpreter
======================

:Description: Enable/disable cleanup of Python interpreter.
:Syntax: ``WSGIDestroyInterpreter On|Off``
:Default: ``WSGIDestroyInterpreter On``
:Context: server config

The ``WSGIDestroyInterpreter`` directive is used to control whether the Python
interpreter is destroyed when processes are shutdown or restarted. By default
the Python interpreter is destroyed when the process is shutdown or restarted.

This directive was added due to changes in Python 3.9 where the Python cleanup
behaviour was changed such that it would wait on daemon threads to complete.
This could cause cleanup of the Python interpreter to hang in some cases
where threads were created external to Python, as is the case where Python
is embedded in a C program such as mod_wsgi with Apache.

If you observe daemon processes hanging at shutdown or restart, set this
directive to ``Off`` to skip Python interpreter destruction::

  WSGIDestroyInterpreter Off

Skipping interpreter destruction means Python ``atexit`` handlers and
any other code registered to run during interpreter finalisation will
not run. For most WSGI applications this is acceptable, since the
daemon process is about to exit anyway and the operating system will
reclaim its resources.

If an application genuinely needs to run cleanup code on process
shutdown and ``WSGIDestroyInterpreter Off`` may be in effect, register
the cleanup callback via ``mod_wsgi.subscribe_shutdown()`` instead of
``atexit``. ``subscribe_shutdown`` callbacks are dispatched by
mod_wsgi directly before interpreter destruction is attempted and
therefore run regardless of this setting. See
:doc:`../user-guides/registering-cleanup-code` for usage.