Ensure gc.collect is not excessively called (#3259)

panel/io/server.py

@@ -2,6 +2,7 @@
 Utilities for creating bokeh Server instances.
 """
 import datetime as dt
+import gc
 import html
 import logging
 import os
@@ -165,6 +166,28 @@ def autoload_js_script(doc, resources, token, element_id, app_path, absolute_url
 
     return AUTOLOAD_JS.render(bundle=bundle, elementid=element_id)
 
+
+def destroy_document(self, session):
+    """
+    Override for Document.destroy() without calling gc.collect directly.
+    The gc.collect() call is scheduled as a task, ensuring that when
+    multiple documents are destroyed in quick succession we do not
+    schedule excessive garbage collection.
+    """
+    self.remove_on_change(session)
+    del self._roots
+    del self._theme
+    del self._template
+    self._session_context = None
+
+    self.callbacks.destroy()
+    self.models.destroy()
+    self.modules.destroy()
+
+    at = dt.datetime.now() + dt.timedelta(seconds=5)
+    state.schedule_task('gc.collect', gc.collect, at=at)
+
+
 # Patch Application to handle session callbacks
 class Application(BkApplication):
 
@@ -349,7 +372,9 @@ def handle_exception(handler, e):
 
         def _log_session_destroyed(session_context):
             logger.info(LOG_SESSION_DESTROYED, id(doc))
+
         doc.on_session_destroyed(_log_session_destroyed)
+        doc.destroy = partial(destroy_document, doc)
     finally:
         state._launching.remove(doc)
         if config.profiler:

panel/io/state.py

@@ -530,7 +530,7 @@ def schedule_task(self, name, callback, at=None, period=None, cron=None):
                     "A separate task was already scheduled under the "
                     f"name {name!r}. The new task will be ignored. If "
                     "you want to replace the existing task cancel it "
-                    "with `state.cancel_task({name!r})` before adding "
+                    f"with `state.cancel_task({name!r})` before adding "
                     "adding a new task under the same name."
                 )
             return