Fixed #13904 - Documented how to avoid garbage collection messages in GIS.

Thanks Claude Peroz for the patch.

docs/ref/contrib/gis/geos.txt

@@ -75,6 +75,17 @@ return a :class:`GEOSGeometry` object from an input string or a file::
     >>> pnt = fromfile('/path/to/pnt.wkt')
     >>> pnt = fromfile(open('/path/to/pnt.wkt'))
 
+.. _geos-exceptions-in-logfile:
+
+.. admonition:: My logs are filled with GEOS-related errors
+
+    You find many ``TypeError`` or ``AttributeError`` exceptions filling your
+    Web server's log files. This generally means that you are creating GEOS
+    objects at the top level of some of your Python modules. Then, due to a race
+    condition in the garbage collector, your module is garbage collected before
+    the GEOS object. To prevent this, create :class:`GEOSGeometry` objects
+    inside the local scope of your functions/methods.
+
 Geometries are Pythonic
 -----------------------
 :class:`GEOSGeometry` objects are 'Pythonic', in other words components may

docs/ref/contrib/gis/install.txt

@@ -191,6 +191,8 @@ GEOS C library.  For example:
     The setting must be the *full* path to the **C** shared library; in
     other words you want to use ``libgeos_c.so``, not ``libgeos.so``.
 
+See also :ref:`My logs are filled with GEOS-related errors <geos-exceptions-in-logfile>`.
+
 .. _proj4:
 
 PROJ.4