Merge pull request #6722 from oliver-sanders/tui-memory-leak

Tui memory leak

Author: wxtim

changes.d/6722.fix.md

@@ -0,0 +1 @@
+Fix a slow memory leak in Tui.

cylc/flow/tui/app.py

@@ -22,13 +22,8 @@
 import re
 
 import urwid
-try:
-    from urwid.widget import SelectableIcon
-except ImportError:
-    # BACK COMPAT: urwid.wimp
-    # From: urwid 2.0
-    # To: urwid 2.2
-    from urwid.wimp import SelectableIcon
+from urwid.canvas import CanvasCache
+from urwid.widget import SelectableIcon
 
 from cylc.flow.id import Tokens
 from cylc.flow.task_state import (
@@ -515,8 +510,11 @@ def update(self, *_):
         _, old_node = self.listbox.body.get_focus()
 
         # nuke the tree
-        self.tree_walker = urwid.TreeWalker(topnode)
-        self.listbox.body = self.tree_walker
+        if not (self.tree_walker):
+            self.tree_walker = urwid.TreeWalker(topnode)
+            self.listbox.body = self.tree_walker
+        else:
+            self.tree_walker.set_focus(topnode)
 
         # get the new focus
         _, new_node = self.listbox.body.get_focus()
@@ -538,6 +536,11 @@ def update(self, *_):
         if self.loop:
             self.loop.set_alarm_in(self.UPDATE_INTERVAL, self.update)
 
+        # NOTE: prevent a memory leak by clearing out any caches that urwid
+        # may have accumulated for the previous TuiNode instance
+        # (and its child widgets)
+        CanvasCache.clear()
+
         return True
 
     def filter_by_task_state(self, filtered_state=None):

setup.cfg

@@ -76,7 +76,7 @@ install_requires =
     pyzmq>=22
     importlib_metadata>=5.0; python_version < "3.12"
     # NOTE: exclude two urwid versions that were not compatible with Tui
-    urwid==2.*,!=2.6.2,!=2.6.3
+    urwid>=2.2,!=2.6.2,!=2.6.3,<3
     # unpinned transient dependencies used for type checking
     rx
     promise