fix: check if alarm list is empty before return

src/monitoring/service/MetricsDBTools.py

@@ -324,8 +324,11 @@ class MetricsDB():
                             alarm = True
                     if alarm:
                         valid_kpi_list.append(kpi)
-                alarm_queue.put_nowait(valid_kpi_list)
-                LOGGER.debug(f"Alarm of KPI {kpi_id} triggered -> kpi_value:{kpi[2]}, timestamp:{kpi[1]}")
+                if valid_kpi_list:
+                    alarm_queue.put_nowait(valid_kpi_list)
+                    LOGGER.debug(f"Alarm of KPI {kpi_id} triggered -> kpi_value:{kpi[2]}, timestamp:{kpi[1]}")
+                else:
+                    LOGGER.debug(f"No new alarms triggered for the alarm of KPI {kpi_id}")
             else:
                 LOGGER.debug(f"No new data for the alarm of KPI {kpi_id}")
         except (Exception) as e: