send batches of at most 10 heartbeats to api

wakatime/main.py

@@ -66,8 +66,7 @@ def execute(argv=None):
         retval = send_heartbeats(heartbeats, args, configs)
         if retval == SUCCESS:
             queue = Queue(args, configs)
-            offline_heartbeats = queue.pop_many(args.sync_offline_activity)
-            if len(offline_heartbeats) > 0:
+            for offline_heartbeats in queue.pop_many(args.sync_offline_activity):
                 retval = send_heartbeats(offline_heartbeats, args, configs)
 
         return retval

wakatime/offlinequeue.py

@@ -115,8 +115,12 @@ class Queue(object):
                 break
             heartbeats.append(heartbeat)
             count += 1
+            if count % 10 == 0:
+                yield heartbeats
+                heartbeats = []
 
-        return heartbeats
+        if heartbeats:
+            yield heartbeats
 
     def _get_db_file(self):
         home = '~'