Add note about fixture teardown and SIGTERM and SIGQUIT signals

doc/en/explanation/fixtures.rst

@@ -156,3 +156,20 @@ Another good approach is by adding the data files in the ``tests`` folder.
 There are also community plugins available to help to manage this aspect of
 testing, e.g. `pytest-datadir <https://pypi.org/project/pytest-datadir/>`__
 and `pytest-datafiles <https://pypi.org/project/pytest-datafiles/>`__.
+
+.. _fixtures-signal-cleanup:
+
+A note about fixture cleanup
+----------------------------
+
+pytest does not do any special processing for :data:`SIGTERM <signal.SIGTERM>` and
+:data:`SIGQUIT <signal.SIGQUIT>` signals (:data:`SIGINT <signal.SIGINT>` is handled naturally
+by the Python runtime via :class:`KeyboardInterrupt`), so fixtures that manage external resources which are important
+to be cleared when the Python process is terminated (by those signals) might leak resources.
+
+The reason pytest does not handle those signals to perform fixture cleanup is that signal handlers are global,
+and changing them might interfere with the code under execution.
+
+If fixtures in your suite need special care regarding termination in those scenarios,
+see `this comment <https://github.com/pytest-dev/pytest/issues/5243#issuecomment-491522595>`__ in the issue
+tracker for a possible workaround.