Re #580 - New functionality - Random "jitter" delay to requests (#681)

changedetectionio/__init__.py

@@ -1287,8 +1287,11 @@ def notification_runner():
 
 # Thread runner to check every minute, look for new watches to feed into the Queue.
 def ticker_thread_check_time_launch_checks():
+    import random
     from changedetectionio import update_worker
-    import logging
+
+    recheck_time_minimum_seconds = int(os.getenv('MINIMUM_SECONDS_RECHECK_TIME', 20))
+    print("System env MINIMUM_SECONDS_RECHECK_TIME", recheck_time_minimum_seconds)
 
     # Spin up Workers that do the fetching
     # Can be overriden by ENV or use the default settings
@@ -1321,14 +1324,12 @@ def ticker_thread_check_time_launch_checks():
         while update_q.qsize() >= 2000:
             time.sleep(1)
 
+
+        recheck_time_system_seconds = int(datastore.threshold_seconds)
+
         # Check for watches outside of the time threshold to put in the thread queue.
-        now = time.time()
-
-        recheck_time_minimum_seconds = int(os.getenv('MINIMUM_SECONDS_RECHECK_TIME', 60))
-        recheck_time_system_seconds = datastore.threshold_seconds
-
         for uuid in watch_uuid_list:
-
+            now = time.time()
             watch = datastore.data['watching'].get(uuid)
             if not watch:
                 logging.error("Watch: {} no longer present.".format(uuid))
@@ -1339,20 +1340,33 @@ def ticker_thread_check_time_launch_checks():
                 continue
 
             # If they supplied an individual entry minutes to threshold.
-            threshold = now
-            watch_threshold_seconds = watch.threshold_seconds()
-            if watch_threshold_seconds:
-                threshold -= watch_threshold_seconds
-            else:
-                threshold -= recheck_time_system_seconds
 
-            # Yeah, put it in the queue, it's more than time
-            if watch['last_checked'] <= max(threshold, recheck_time_minimum_seconds):
+            watch_threshold_seconds = watch.threshold_seconds()
+            threshold = watch_threshold_seconds if watch_threshold_seconds > 0 else recheck_time_system_seconds
+
+            # #580 - Jitter plus/minus amount of time to make the check seem more random to the server
+            jitter = datastore.data['settings']['requests'].get('jitter_seconds', 0)
+            if jitter > 0:
+                if watch.jitter_seconds == 0:
+                    watch.jitter_seconds = random.uniform(-abs(jitter), jitter)
+
+
+            seconds_since_last_recheck = now - watch['last_checked']
+            if seconds_since_last_recheck >= (threshold + watch.jitter_seconds) and seconds_since_last_recheck >= recheck_time_minimum_seconds:
                 if not uuid in running_uuids and uuid not in update_q.queue:
+                    print("Queued watch UUID {} last checked at {} queued at {:0.2f} jitter {:0.2f}s, {:0.2f}s since last checked".format(uuid,
+                                                                                                         watch['last_checked'],
+                                                                                                         now,
+                                                                                                         watch.jitter_seconds,
+                                                                                                         now - watch['last_checked']))
+                    # Into the queue with you
                     update_q.put(uuid)
 
-        # Wait a few seconds before checking the list again
-        time.sleep(3)
+                    # Reset for next time
+                    watch.jitter_seconds = 0
+
+        # Wait before checking the list again - saves CPU
+        time.sleep(1)
 
         # Should be low so we can break this out in testing
         app.config.exit.wait(1)