Tighten up teardown logic

- Stop active DB update work before tearing down executor pools.
- Short-circuit scan completion callbacks during shutdown so in-flight timer ticks don’t queue follow-up work.
- Prevent the download monitor from draining deferred/completed tasks after shutdown starts.
- Make listening stats startup stop-aware so it exits cleanly if teardown begins during warmup.
- If a metadata update is already running, it can now observe should_stop and exit cleanly instead of continuing after SIGTERM.

core/listening_stats_worker.py

@@ -90,15 +90,20 @@ class ListeningStatsWorker:
         logger.info("Listening stats worker thread started")
 
         # Build cache from existing data immediately (before first poll)
-        interruptible_sleep(self._stop_event, 5)
+        if interruptible_sleep(self._stop_event, 5):
+            return
         try:
             self._build_stats_cache()
             logger.info("Initial stats cache built from existing data")
         except Exception as e:
             logger.debug(f"Initial cache build skipped: {e}")
 
+        if self.should_stop:
+            return
+
         # Wait before first poll
-        interruptible_sleep(self._stop_event, 10)
+        if interruptible_sleep(self._stop_event, 10):
+            return
 
         while not self.should_stop:
             try:

core/media_scan_manager.py

@@ -256,6 +256,8 @@ class MediaScanManager:
             if is_scanning:
                 # Still scanning - trigger database update and continue periodic updates
                 logger.info(f"{server_type.upper()} still scanning - triggering database update")
+                if self._shutting_down:
+                    return
                 self._call_completion_callbacks()
                 
                 # Schedule next periodic update
@@ -268,6 +270,8 @@ class MediaScanManager:
             else:
                 # Scanning stopped - final update and cleanup
                 logger.info(f"{server_type.upper()} scanning completed - doing final database update")
+                if self._shutting_down:
+                    return
                 self._call_completion_callbacks()
                 self._stop_periodic_updates()
                 

core/plex_scan_manager.py

@@ -174,6 +174,8 @@ class PlexScanManager:
             if is_scanning:
                 # Still scanning - trigger database update and continue periodic updates
                 logger.info("Plex still scanning - triggering database update")
+                if self._shutting_down:
+                    return
                 self._call_completion_callbacks()
                 
                 # Schedule next periodic update
@@ -186,6 +188,8 @@ class PlexScanManager:
             else:
                 # Scanning stopped - final update and cleanup
                 logger.info("Plex scanning completed - doing final database update")
+                if self._shutting_down:
+                    return
                 self._call_completion_callbacks()
                 self._stop_periodic_updates()
                 

core/web_scan_manager.py

@@ -290,12 +290,19 @@ class WebScanManager:
 
     def _handle_scan_completion(self):
         """Handle scan completion and trigger callbacks"""
-        logger.info(f"Web {self._current_server_type.upper()} library scan completed")
-
-        # Call completion callbacks
-        callbacks_to_call = []
         with self._lock:
+            if self._shutting_down:
+                return
+            server_type = self._current_server_type
             callbacks_to_call = self._scan_completion_callbacks.copy()
+            downloads_during_scan = self._downloads_during_scan
+
+        if not server_type:
+            logger.debug("Skipping web scan completion: no active server type")
+            self._reset_scan_state()
+            return
+
+        logger.info(f"Web {server_type.upper()} library scan completed")
 
         for callback in callbacks_to_call:
             try:
@@ -308,10 +315,9 @@ class WebScanManager:
         self._reset_scan_state()
 
         # Check if we need another scan due to downloads during this scan
-        with self._lock:
-            if self._downloads_during_scan:
-                logger.info("Web scan follow-up needed for downloads during scan")
-                self.request_scan("Follow-up scan for downloads during previous scan")
+        if downloads_during_scan:
+            logger.info("Web scan follow-up needed for downloads during scan")
+            self.request_scan("Follow-up scan for downloads during previous scan")
 
     def _reset_scan_state(self):
         """Reset internal scan state"""

web_server.py

@@ -2638,6 +2638,8 @@ class WebUIDownloadMonitor:
                                 completed_tasks.append((batch_id, task_id))
 
         # ---- All work below runs WITHOUT tasks_lock held ----
+        if globals().get('IS_SHUTTING_DOWN', False) or not self.monitoring:
+            return
 
         # Execute deferred operations from _should_retry_task (network calls, nested locks)
         for op in deferred_ops:
@@ -3460,6 +3462,11 @@ def _shutdown_runtime_components():
     except Exception as e:
         print(f"Error saving API call history: {e}")
 
+    # Stop the active DB update worker before tearing down the executor it runs on.
+    # This lets an in-flight update observe should_stop and exit cleanly.
+    _stop_component(db_update_worker, "db update worker")
+    _stop_component(metadata_update_runtime_worker, "metadata update worker")
+
     # Stop long-lived worker components in parallel so shutdown waits for the
     # slowest worker instead of serially burning the timeout for each one.
     _stop_components_parallel([
@@ -40789,6 +40796,7 @@ metadata_update_state = {
 }
 
 metadata_update_worker = None
+metadata_update_runtime_worker = None
 metadata_update_executor = ThreadPoolExecutor(max_workers=1, thread_name_prefix="metadata_update")
 
 # ===============================
@@ -44903,7 +44911,7 @@ def _old_get_listenbrainz_playlist_tracks_DEPRECATED(playlist_mbid):
 @app.route('/api/metadata/start', methods=['POST'])
 def start_metadata_update():
     """Start the metadata update process - EXACT copy of dashboard.py logic"""
-    global metadata_update_worker, metadata_update_state
+    global metadata_update_worker, metadata_update_runtime_worker, metadata_update_state
     
     try:
         # Check if already running
@@ -44971,6 +44979,7 @@ def start_metadata_update():
         
         # Start the metadata update worker - EXACTLY like dashboard.py
         def run_metadata_update():
+            global metadata_update_runtime_worker
             try:
                 metadata_worker = WebMetadataUpdateWorker(
                     None,  # Artists will be loaded in the worker thread - EXACTLY like dashboard.py
@@ -44979,12 +44988,15 @@ def start_metadata_update():
                     active_server,
                     refresh_interval_days
                 )
+                metadata_update_runtime_worker = metadata_worker
                 metadata_worker.run()
             except Exception as e:
                 print(f"Error in metadata update worker: {e}")
                 metadata_update_state['status'] = 'error'
                 metadata_update_state['error'] = str(e)
                 add_activity_item("", "Metadata Error", str(e), "Now")
+            finally:
+                metadata_update_runtime_worker = None
         
         metadata_update_worker = metadata_update_executor.submit(run_metadata_update)