Merge pull request matplotlib#23059 from greglucas/macosx-manager-refcount

FIX: Decrease figure refcount on close of a macosx figure

Author: tacaswell

lib/matplotlib/backends/backend_macosx.py

@@ -37,6 +37,8 @@ def __init__(self, figure):
         super().__init__(figure=figure)
         self._draw_pending = False
         self._is_drawing = False
+        # Keep track of the timers that are alive
+        self._timers = set()
 
     def draw(self):
         """Render the figure and update the macosx canvas."""
@@ -59,14 +61,16 @@ def draw_idle(self):
 
     def _single_shot_timer(self, callback):
         """Add a single shot timer with the given callback"""
-        # We need to explicitly stop (called from delete) the timer after
+        # We need to explicitly stop and remove the timer after
         # firing, otherwise segfaults will occur when trying to deallocate
         # the singleshot timers.
         def callback_func(callback, timer):
             callback()
-            del timer
+            self._timers.remove(timer)
+            timer.stop()
         timer = self.new_timer(interval=0)
         timer.add_callback(callback_func, callback, timer)
+        self._timers.add(timer)
         timer.start()
 
     def _draw_idle(self):
@@ -150,6 +154,14 @@ def _close_button_pressed(self):
         Gcf.destroy(self)
         self.canvas.flush_events()
 
+    def destroy(self):
+        # We need to clear any pending timers that never fired, otherwise
+        # we get a memory leak from the timer callbacks holding a reference
+        while self.canvas._timers:
+            timer = self.canvas._timers.pop()
+            timer.stop()
+        super().destroy()
+
     @classmethod
     def start_main_loop(cls):
         _macosx.show()

src/_macosx.m

@@ -193,7 +193,6 @@ @interface Window : NSWindow
 - (Window*)initWithContentRect:(NSRect)rect styleMask:(unsigned int)mask backing:(NSBackingStoreType)bufferingType defer:(BOOL)deferCreation withManager: (PyObject*)theManager;
 - (NSRect)constrainFrameRect:(NSRect)rect toScreen:(NSScreen*)screen;
 - (BOOL)closeButtonPressed;
-- (void)dealloc;
 @end
 
 @interface View : NSView <NSWindowDelegate>
@@ -1239,19 +1238,9 @@ - (void)close
     /* This is needed for show(), which should exit from [NSApp run]
      * after all windows are closed.
      */
-}
-
-- (void)dealloc
-{
-    PyGILState_STATE gstate;
-    gstate = PyGILState_Ensure();
+    // For each new window, we have incremented the manager reference, so
+    // we need to bring that down during close and not just dealloc.
     Py_DECREF(manager);
-    PyGILState_Release(gstate);
-    /* The reference count of the view that was added as a subview to the
-     * content view of this window was increased during the call to addSubview,
-     * and is decreased during the call to [super dealloc].
-     */
-    [super dealloc];
 }
 @end