Hi Poornapragna I'll try to answer your questions 1. you don't need to delete the timer manually(it will be deleted after fired), but you can delete the timers manually if you want. 2. AFAIK, triggers would not be snapshot out, but the timers will be snapshot out 3. delete timer that was not register would not be problematic[1] 4. from my understand, the triggers you can use out-of-box can't achieve your purpose. 5.window will be triggered when watermark exceed the end-of-window, but currently we do not snapshot watermark when checkpointing[2], so if you're using event-time, maybe it will be triggered a little late(dependent on the watermark generate logic you wrote).
[1] https://github.com/apache/flink/blob/master/flink-streaming-java/src/main/java/org/apache/flink/streaming/api/operators/InternalTimerServiceImpl.java [2] https://issues.apache.org/jira/browse/FLINK-5601 Best, Congxian Poornapragna Ts <itsme.poorna....@gmail.com> 于2020年5月29日周五 上午12:38写道： > Hi, > > I have a simple requirement where i want to have 10 second window with > allow late events upto 1 hour. > > Existing TumblingEventTimeWindows with EventTimeTrigger will work for this. > > But the EventTimeTrigger, triggers for every incoming event after > watermark has passed windows max time. I don't want this behaviour. Even > for late events, I want to fire for every 10 seconds. > > For this, I thought of writing custom trigger, which will be similar to > EventTimeTrigger, but instead of firing on every late event, it will > register timer in onElement method for upcoming 10th second. > > With this setup, I have some questions. > > 1) When we register timers to context, is it compulsory to delete them on > clear() call? > > 2) Will these triggers be stored in fault tolerance state? So that > deleting is must. > > 3) Will it be problematic, if I call delete trigger for unregistered time( > i.e., if I call delete for time T1 for which I had not registered before.) > > 4) Without implementing custom trigger, can it be achieved? > > 5) Lets say, late event came at 255 second so I will register a timer to > trigger at 260(next 10th second). If a failure happens before that time, > then restarting from the checkpoint, Will it trigger when watermark reaches > 260? That means will the trigger be recovered when we restart from > failure. > > Thanks, > Poornapragna T S >
