Merge pull request matplotlib#26302 from tacaswell/fix/tightlayout_threading

FIX: move the font lock higher up the call and class tree

Author: ksunden

lib/matplotlib/backend_bases.py

@@ -170,7 +170,6 @@ class RendererBase:
     * `draw_path_collection`
     * `draw_quad_mesh`
     """
-
     def __init__(self):
         super().__init__()
         self._texmanager = None
@@ -2147,9 +2146,10 @@ def print_figure(
                     functools.partial(
                         print_method, orientation=orientation)
                 )
+                # we do this instead of `self.figure.draw_without_rendering`
+                # so that we can inject the orientation
                 with getattr(renderer, "_draw_disabled", nullcontext)():
                     self.figure.draw(renderer)
-
             if bbox_inches:
                 if bbox_inches == "tight":
                     bbox_inches = self.figure.get_tightbbox(

lib/matplotlib/backends/backend_agg.py

@@ -23,7 +23,6 @@
 
 from contextlib import nullcontext
 from math import radians, cos, sin
-import threading
 
 import numpy as np
 
@@ -62,19 +61,6 @@ class RendererAgg(RendererBase):
     context instance that controls the colors/styles
     """
 
-    # we want to cache the fonts at the class level so that when
-    # multiple figures are created we can reuse them.  This helps with
-    # a bug on windows where the creation of too many figures leads to
-    # too many open file handles.  However, storing them at the class
-    # level is not thread safe.  The solution here is to let the
-    # FigureCanvas acquire a lock on the fontd at the start of the
-    # draw, and release it when it is done.  This allows multiple
-    # renderers to share the cached fonts, but only one figure can
-    # draw at time and so the font cache is used by only one
-    # renderer at a time.
-
-    lock = threading.RLock()
-
     def __init__(self, width, height, dpi):
         super().__init__()
 
@@ -395,8 +381,7 @@ def draw(self):
         self.renderer = self.get_renderer()
         self.renderer.clear()
         # Acquire a lock on the shared font cache.
-        with RendererAgg.lock, \
-             (self.toolbar._wait_cursor_for_draw_cm() if self.toolbar
+        with (self.toolbar._wait_cursor_for_draw_cm() if self.toolbar
               else nullcontext()):
             self.figure.draw(self.renderer)
             # A GUI class may be need to update a window using this draw, so

lib/matplotlib/figure.py

@@ -35,6 +35,7 @@
 import itertools
 import logging
 from numbers import Integral
+import threading
 
 import numpy as np
 
@@ -2365,6 +2366,18 @@ class Figure(FigureBase):
         *suppressComposite* is a boolean, this will override the renderer.
     """
 
+    # we want to cache the fonts and mathtext at a global level so that when
+    # multiple figures are created we can reuse them.  This helps with a bug on
+    # windows where the creation of too many figures leads to too many open
+    # file handles and improves the performance of parsing mathtext.  However,
+    # these global caches are not thread safe.  The solution here is to let the
+    # Figure acquire a shared lock at the start of the draw, and release it when it
+    # is done.  This allows multiple renderers to share the cached fonts and
+    # parsed text, but only one figure can draw at a time and so the font cache
+    # and mathtext cache are used by only one renderer at a time.
+
+    _render_lock = threading.RLock()
+
     def __str__(self):
         return "Figure(%gx%g)" % tuple(self.bbox.size)
 
@@ -3124,33 +3137,33 @@ def clear(self, keep_observers=False):
     @allow_rasterization
     def draw(self, renderer):
         # docstring inherited
-
-        # draw the figure bounding box, perhaps none for white figure
         if not self.get_visible():
             return
 
-        artists = self._get_draw_artists(renderer)
-        try:
-            renderer.open_group('figure', gid=self.get_gid())
-            if self.axes and self.get_layout_engine() is not None:
-                try:
-                    self.get_layout_engine().execute(self)
-                except ValueError:
-                    pass
-                    # ValueError can occur when resizing a window.
+        with self._render_lock:
 
-            self.patch.draw(renderer)
-            mimage._draw_list_compositing_images(
-                renderer, self, artists, self.suppressComposite)
+            artists = self._get_draw_artists(renderer)
+            try:
+                renderer.open_group('figure', gid=self.get_gid())
+                if self.axes and self.get_layout_engine() is not None:
+                    try:
+                        self.get_layout_engine().execute(self)
+                    except ValueError:
+                        pass
+                        # ValueError can occur when resizing a window.
 
-            for sfig in self.subfigs:
-                sfig.draw(renderer)
+                self.patch.draw(renderer)
+                mimage._draw_list_compositing_images(
+                    renderer, self, artists, self.suppressComposite)
 
-            renderer.close_group('figure')
-        finally:
-            self.stale = False
+                for sfig in self.subfigs:
+                    sfig.draw(renderer)
+
+                renderer.close_group('figure')
+            finally:
+                self.stale = False
 
-        DrawEvent("draw_event", self.canvas, renderer)._process()
+            DrawEvent("draw_event", self.canvas, renderer)._process()
 
     def draw_without_rendering(self):
         """

lib/matplotlib/tests/test_figure.py

@@ -1644,3 +1644,18 @@ def test_get_constrained_layout_pads():
     fig = plt.figure(layout=mpl.layout_engine.ConstrainedLayoutEngine(**params))
     with pytest.warns(PendingDeprecationWarning, match="will be deprecated"):
         assert fig.get_constrained_layout_pads() == expected
+
+
+def test_not_visible_figure():
+    fig = Figure()
+
+    buf = io.StringIO()
+    fig.savefig(buf, format='svg')
+    buf.seek(0)
+    assert '<g ' in buf.read()
+
+    fig.set_visible(False)
+    buf = io.StringIO()
+    fig.savefig(buf, format='svg')
+    buf.seek(0)
+    assert '<g ' not in buf.read()