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From Aljoscha Krettek <aljos...@apache.org>
Subject Re: Delay in Flink timers
Date Thu, 14 Sep 2017 10:34:42 GMT

Yes, execution of these methods is protected by a synchronized block. This is not a fair lock
so incoming data might starve timer callbacks. What is the number of timers we are talking
about here?


> On 11. Sep 2017, at 19:38, Chesnay Schepler <c.schepler@web.de> wrote:
> It is true that onTimer and processElement are never called at the same time.
> I'm not entirely sure whether there is any prioritization/fairness between these methods
> (if not if could be that onTimer is starved) , looping in Aljoscha who hopefully knows
> about this.
> On 10.09.2017 09:31, Narendra Joshi wrote:
>> Hi,
>> We are using Flink as a timer scheduler and delay in timer execution is
>> a huge problem for us. What we have experienced is that as the number of
>> Timers we register increases the timers start getting delayed (for more
>> than 5 seconds). Can anyone point us in the right direction to figure
>> out what might be happening?
>> I have been told that `onTimer` and `processElement` are called with a
>> mutually exclusive lock. Could this locking be the reason this is
>> happening? In both the functions there is no IO happening and it should
>> not take 5 seconds.
>> Is it possible that calls to `processElement` starve `onTimer` calls?
>> --
>> Narendra Joshi

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