Add warning if poor performance is detected (#145)

Author: Archmonger

CHANGELOG.md

@@ -34,7 +34,9 @@ Using the following categories, list your changes in this order:
 
 ## [Unreleased]
 
--   Nothing (yet)
+### Added
+
+-   Added warning if poor system/cache/database performance is detected.
 
 ## [3.1.0] - 2023-05-06
 

src/reactpy_django/utils.py

@@ -316,6 +316,7 @@ def db_cleanup(immediate: bool = False):
     from .config import REACTPY_CACHE, REACTPY_DATABASE, REACTPY_RECONNECT_MAX
     from .models import ComponentSession
 
+    clean_started_at = datetime.now()
     cache_key: str = create_cache_key("last_cleaned")
     now_str: str = datetime.strftime(timezone.now(), DATE_FORMAT)
     cleaned_at_str: str = caches[REACTPY_CACHE].get(cache_key)
@@ -340,3 +341,12 @@ def db_cleanup(immediate: bool = False):
             last_accessed__lte=expires_by
         ).delete()
         caches[REACTPY_CACHE].set(cache_key, now_str, timeout=None)
+
+    # Check if cleaning took abnormally long
+    clean_duration = datetime.now() - clean_started_at
+    if clean_duration.total_seconds() > 1:
+        _logger.warning(
+            "ReactPy has taken %s seconds to clean up expired component sessions. "
+            "This may indicate a performance issue with your system, cache, or database.",
+            clean_duration.total_seconds(),
+        )

src/reactpy_django/websocket/consumer.py

@@ -77,7 +77,7 @@ async def _run_dispatch_loop(self):
             carrier=ComponentWebsocket(self.close, self.disconnect, dotted_path),
         )
         now = timezone.now()
-        component_args: Sequence[Any] = tuple()
+        component_args: Sequence[Any] = ()
         component_kwargs: MutableMapping[str, Any] = {}
 
         # Verify the component has already been registered