Fix Kodi crash by committing to DB frequently

- Hopefully fixes #531

resources/lib/library_sync/process_metadata.py

@@ -12,6 +12,11 @@ from . import sync_info
 ###############################################################################
 LOG = getLogger("PLEX." + __name__)
 
+# Commit to DB happens only after leaving respective itemtypes context manager
+#    with item_fct() as item_class:
+# After how many items shall we additionally commit? Otherwise, Kodi
+# crashes if we sync thousands of items without a single commit.
+COMMIT_AFTER_N_ITEMS = 1000
 ###############################################################################
 
 
@@ -57,14 +62,12 @@ class ThreadedProcessMetadata(Thread):
         LOG.debug('Processing thread started')
         # Constructs the method name, e.g. itemtypes.Movies
         item_fct = getattr(itemtypes, self.item_class)
-        # cache local variables because it's faster
+        n = 0
-        queue = self.queue
-        stopped = self.stopped
         with item_fct() as item_class:
-            while stopped() is False:
+            while self.stopped() is False:
                 # grabs item from queue
                 try:
-                    item = queue.get(block=False)
+                    item = self.queue.get(block=False)
                 except Empty:
                     sleep(20)
                     continue
@@ -83,6 +86,11 @@ class ThreadedProcessMetadata(Thread):
                 with sync_info.LOCK:
                     sync_info.PROCESS_METADATA_COUNT += 1
                     sync_info.PROCESSING_VIEW_NAME = item['title']
-                queue.task_done()
+                n += 1
+                if n == COMMIT_AFTER_N_ITEMS:
+                    n = 0
+                    item_class.plexconn.commit()
+                    item_class.kodiconn.commit()
+                self.queue.task_done()
         self.terminate_now()
         LOG.debug('Processing thread terminated')