Hi Thanks for the multiple responses on this question. Please correct me if I am wrong about the 3 possible ways of it: 1. As per FLINK-3089, RocksDB based timer implementation is efficient. But it is not merged yet. Which release this will be part of? 2. FLINK-6359 suggests alternate approach based using Hierarchical timing wheels. 3. We can use state to indicate whether to trigger or not but timer will fire in all the cases. So this is not actually a cancellation of timer.
In our use case we have ~ 1000 events per sec. But number of cancellations done will be much more. (i.e. as per the business logic, number of timers which will need to be cancelled are more say 70%), so solution 3 can be inefficient and a bit of wastage of resources. So, Could you please recommend how should I go about it? -- Which release item 1 or item 3 can be part of? -- About the existing implementation, are there any approximate data points about how slow deletion is? (if RPS is 1000 and assuming any standard AWS instance type.) I can derive from that and decide based on data that to go with cancellations or not. On Sat, Apr 22, 2017 at 8:13 PM, Ted Yu <yuzhih...@gmail.com> wrote: > Logged FLINK-6359, referring to this thread. > > FYI > > On Sat, Apr 22, 2017 at 1:10 AM, Gyula Fóra <gyf...@apache.org> wrote: > >> Hi, >> >> I am not familiar with this data structure, I will try to read up on it. >> But it looks interesting. >> >> For some reference, some links: >> >> https://www.confluent.io/blog/apache-kafka-purgatory-hierarc >> hical-timing-wheels/ >> >> http://www.cs.columbia.edu/~nahum/w6998/papers/sosp87-timing-wheels.pdf >> >> Cheers, >> Gyula >> >> On Sat, Apr 22, 2017, 00:35 Ted Yu <yuzhih...@gmail.com> wrote: >> >>> Benjamin has an implementation for Hierarchical Timing Wheels (Apache >>> License) : >>> >>> https://github.com/ben-manes/caffeine/blob/master/caffeine/s >>> rc/main/java/com/github/benmanes/caffeine/cache/TimerWheel.java >>> >>> If there is some interest, we can port the above over. >>> >>> Cheers >>> >>> On Fri, Apr 21, 2017 at 12:44 PM, Gyula Fóra <gyf...@apache.org> wrote: >>> >>>> The timer will actually fire and will be removed at the original time, >>>> but we don't trigger any action on it. We also remove the tombstone state >>>> afterwards. >>>> >>>> So we use more memory yes depending on the length and number of timers >>>> that were deleted. But it is eventually cleaned up. >>>> >>>> Gyula >>>> >>>> Ted Yu <yuzhih...@gmail.com> ezt írta (időpont: 2017. ápr. 21., P, >>>> 21:38): >>>> >>>>> A bit curious: wouldn't using "tombstone" markers constitute some >>>>> memory leak (since Timers are not released) ? >>>>> >>>>> Cheers >>>>> >>>>> On Fri, Apr 21, 2017 at 12:23 PM, Gyula Fóra <gyf...@apache.org> >>>>> wrote: >>>>> >>>>>> Hi! >>>>>> >>>>>> I thought I would drop my opinion here maybe it is relevant. >>>>>> >>>>>> We have used the Flink internal timer implementation in many of our >>>>>> production applications, this supports the Timer deletion but the >>>>>> deletion >>>>>> actually turned out to be a huge performance bottleneck because of the >>>>>> bad >>>>>> deletion performance of the Priority queue. >>>>>> >>>>>> In many of our cases deletion could have been avoided by some more >>>>>> clever registration/firing logic and we also ended up completely avoiding >>>>>> deletion and instead using "tombstone" markers by setting a flag in the >>>>>> state which timers not to fire when they actually trigger. >>>>>> >>>>>> Gyula >>>>>> >>>>>> >>>>>> >>>>>> Aljoscha Krettek <aljos...@apache.org> ezt írta (időpont: 2017. ápr. >>>>>> 21., P, 14:47): >>>>>> >>>>>>> Hi, >>>>>>> the reasoning behind the limited user facing API was that we were >>>>>>> (are) not sure whether we would be able to support efficient deletion of >>>>>>> timers for different ways of storing timers. >>>>>>> >>>>>>> @Stephan, If I remember correctly you were the strongest advocate >>>>>>> for not allowing timer deletion. What’s your thinking on this? There was >>>>>>> also a quick discussion on https://issues.apache.org/j >>>>>>> ira/browse/FLINK-3089 where Xiaogang explained that the (new, not >>>>>>> merged) RocksDB based timers would have efficient timer deletion. >>>>>>> >>>>>>> Best, >>>>>>> Aljoscha >>>>>>> >>>>>>> On 20. Apr 2017, at 11:56, Jagadish Bihani <jagad...@helpshift.com> >>>>>>> wrote: >>>>>>> >>>>>>> Hi >>>>>>> >>>>>>> I am working on a use case where I want to start a timer for a given >>>>>>> event type and when that timer expires it will perform certain action. >>>>>>> This >>>>>>> can be done using Process Function. >>>>>>> >>>>>>> But I also want to cancel scheduled timer in case of some other >>>>>>> types of events. I also checked the implementation of >>>>>>> HeapInternalTimerService which implements InternalTimerService interface >>>>>>> has those implementations already. Also SimpleTimerService which >>>>>>> overrides >>>>>>> TimerService also uses InternalTimerService and simply passes >>>>>>> VoidNamespace.INSTANCE. >>>>>>> >>>>>>> So in a way we are using InternalTimerService interface's >>>>>>> implementations everywhere. >>>>>>> >>>>>>> So what is the reason that ProcessFunction.Context uses >>>>>>> TimerService? Any reason 'deleteEventTimeTimer' is not exposed to >>>>>>> users? If >>>>>>> I want to use the deleteEvent functionality how should I go about it? >>>>>>> >>>>>>> -- >>>>>>> Thanks and Regards, >>>>>>> Jagadish Bihani >>>>>>> >>>>>>> >>>>>>> >>>>> >>> > -- Thanks and Regards, Jagadish Bihani
