WIP: Reduce memory usage in doc build (mne-tools#9448)

* WIP: Show problem [circle front]

* restore scraping

* Revert "restore scraping"

This reverts commit 045fbff.

* Fix

* Fix [circle full]

Co-authored-by: Guillaume Favelier <[email protected]>

doc/conf.py

@@ -286,15 +286,30 @@ def __call__(self, gallery_conf, fname):
             from pyvista import Plotter  # noqa
         except ImportError:
             Plotter = None  # noqa
+        try:
+            from pyvistaqt import BackgroundPlotter  # noqa
+        except ImportError:
+            BackgroundPlotter = None  # noqa
+        try:
+            from vtk import vtkPolyData  # noqa
+        except ImportError:
+            vtkPolyData = None  # noqa
+        from mne.viz.backends.renderer import backend
+        _Renderer = backend._Renderer if backend is not None else None
         reset_warnings(gallery_conf, fname)
         # in case users have interactive mode turned on in matplotlibrc,
         # turn it off here (otherwise the build can be very slow)
         plt.ioff()
         plt.rcParams['animation.embed_limit'] = 30.
         gc.collect()
-        # _assert_no_instances(Brain, 'running')  # calls gc.collect()
-        # if Plotter is not None:
-        #     _assert_no_instances(Plotter, 'running')
+        _assert_no_instances(Brain, 'Brain')  # calls gc.collect()
+        if Plotter is not None:
+            _assert_no_instances(Plotter, 'Plotter')
+        if BackgroundPlotter is not None:
+            _assert_no_instances(BackgroundPlotter, 'BackgroundPlotter')
+        if vtkPolyData is not None:
+            _assert_no_instances(vtkPolyData, 'vtkPolyData')
+        _assert_no_instances(_Renderer, '_Renderer')
         # This will overwrite some Sphinx printing but it's useful
         # for memory timestamps
         if os.getenv('SG_STAMP_STARTS', '').lower() == 'true':
@@ -309,38 +324,32 @@ def __call__(self, gallery_conf, fname):
 os.environ['_MNE_BUILDING_DOC'] = 'true'
 scrapers = ('matplotlib',)
 try:
-    mlab = mne.utils._import_mlab()
-    # Do not pop up any mayavi windows while running the
-    # examples. These are very annoying since they steal the focus.
-    mlab.options.offscreen = True
-    # hack to initialize the Mayavi Engine
-    mlab.test_plot3d()
-    mlab.close()
-except Exception:
-    pass
-else:
-    scrapers += ('mayavi',)
-try:
-    with warnings.catch_warnings():
-        warnings.filterwarnings("ignore", category=DeprecationWarning)
-        import pyvista
-    pyvista.OFF_SCREEN = False
+    mne.viz.set_3d_backend(mne.viz.get_3d_backend())
 except Exception:
-    pass
+    report_scraper = None
 else:
-    scrapers += ('pyvista',)
-if any(x in scrapers for x in ('pyvista', 'mayavi')):
-    from traits.api import push_exception_handler
-    push_exception_handler(reraise_exceptions=True)
+    backend = mne.viz.get_3d_backend()
+    if backend == 'mayavi':
+        from traits.api import push_exception_handler
+        mlab = mne.utils._import_mlab()
+        # Do not pop up any mayavi windows while running the
+        # examples. These are very annoying since they steal the focus.
+        mlab.options.offscreen = True
+        # hack to initialize the Mayavi Engine
+        mlab.test_plot3d()
+        mlab.close()
+        scrapers += ('mayavi',)
+        push_exception_handler(reraise_exceptions=True)
+    elif backend in ('notebook', 'pyvista'):
+        with warnings.catch_warnings():
+            warnings.filterwarnings("ignore", category=DeprecationWarning)
+            import pyvista
+        pyvista.OFF_SCREEN = False
+        brain_scraper = mne.viz._brain._BrainScraper()
+        scrapers += (brain_scraper, 'pyvista')
     report_scraper = mne.report._ReportScraper()
     scrapers += (report_scraper,)
-else:
-    report_scraper = None
-if 'pyvista' in scrapers:
-    brain_scraper = mne.viz._brain._BrainScraper()
-    scrapers = list(scrapers)
-    scrapers.insert(scrapers.index('pyvista'), brain_scraper)
-    scrapers = tuple(scrapers)
+    del backend
 
 sphinx_gallery_conf = {
     'doc_module': ('mne',),

mne/utils/misc.py

@@ -347,6 +347,12 @@ def _assert_no_instances(cls, when=''):
                         not inspect.isframe(r):
                     if isinstance(r, (list, dict)):
                         rep = f'len={len(r)}'
+                        r_ = gc.get_referrers(r)
+                        types = (x.__class__.__name__ for x in r_)
+                        types = "/".join(sorted(set(
+                            x for x in types if x is not None)))
+                        rep += f', {len(r_)} referrers: {types}'
+                        del r_
                     else:
                         rep = repr(r)[:100].replace('\n', ' ')
                     ref.append(f'{r.__class__.__name__}: {rep}')

mne/viz/backends/_pyvista.py

@@ -193,11 +193,17 @@ def __init__(self, fig=None, size=(600, 600), bgcolor='black',
 
     @property
     def _all_plotters(self):
-        return [self.figure.plotter]
+        if self.figure.plotter is not None:
+            return [self.figure.plotter]
+        else:
+            return list()
 
     @property
     def _all_renderers(self):
-        return self.figure.plotter.renderers
+        if self.figure.plotter is not None:
+            return self.figure.plotter.renderers
+        else:
+            return list()
 
     def _hide_axes(self):
         for renderer in self._all_renderers:
@@ -1014,13 +1020,15 @@ def _check_3d_figure(figure):
 def _close_3d_figure(figure):
     with warnings.catch_warnings():
         warnings.filterwarnings("ignore", category=FutureWarning)
+        # copy the plotter locally because figure.plotter is modified
+        plotter = figure.plotter
         # close the window
-        figure.plotter.close()
-        _process_events(figure.plotter)
+        plotter.close()  # additional cleaning following signal_close
+        _process_events(plotter)
         # free memory and deregister from the scraper
-        figure.plotter.deep_clean()
-        del _ALL_PLOTTERS[figure.plotter._id_name]
-        _process_events(figure.plotter)
+        plotter.deep_clean()  # remove internal references
+        del _ALL_PLOTTERS[plotter._id_name]
+        _process_events(plotter)
 
 
 def _take_3d_screenshot(figure, mode='rgb', filename=None):

mne/viz/backends/_qt.py

@@ -368,6 +368,11 @@ def _window_initialize(self):
         self._interactor = self.figure.plotter.interactor
         self._window = self.figure.plotter.app_window
         self._window.setLocale(QLocale(QLocale.Language.English))
+        self._window.signal_close.connect(self._window_clean)
+
+    def _window_clean(self):
+        self.figure.plotter = None
+        self._interactor = None
 
     def _window_close_connect(self, func):
         self._window.signal_close.connect(func)

tutorials/forward/35_eeg_no_mri.py

@@ -77,11 +77,6 @@
                                 bem=bem, eeg=True, mindist=5.0, n_jobs=1)
 print(fwd)
 
-# Use fwd to compute the sensitivity map for illustration purposes
-eeg_map = mne.sensitivity_map(fwd, ch_type='eeg', mode='fixed')
-brain = eeg_map.plot(time_label='EEG sensitivity', subjects_dir=subjects_dir,
-                     clim=dict(lims=[5, 50, 100]))
-
 ##############################################################################
 # From here on, standard inverse imaging methods can be used!
 #