Re: FLIP-16, FLIP-15 Status Updates?

2019-02-21 Thread Paris Carbone
I created these FLIPs a while back, sorry for being late to this discussion but I can try to elaborate. The idea from FLIP-16 is proven to be correct [1] (see chapter 3) and I think it is the only way to go but I have been in favour of providing channel implementations with checkpoint behaviour

Re: Superstep-like synchronization of streaming iteration

2018-10-01 Thread Paris Carbone
prototype please do PM me! Paris [1] https://www.slideshare.net/FlinkForward/flink-forward-berlin-2018-paris-carbone-stream-loops-on-flink-reinventing-the-wheel-for-the-streaming-era > On 29 Sep 2018, at 20:51, Christian Lehner > wrote: > > Hi all, > > > if you don'

Re: Iterative Stream won't loop

2018-05-11 Thread Paris Carbone
Hey! I would recommend against using iterations with windows for that problem at the moment. Alongside loop scoping and backpressure that will be addressed by FLIP-15 [1] I think you also need the notion of stream supersteps, which is experimental work in progress for now, from my side at least

Re: Which test cluster to use for checkpointing tests?

2018-03-06 Thread Paris Carbone
Hey, Indeed checkpointing iterations and dealing with closed sources are orthogonal issues, that is why the latter is not part of FLIP-15. Though, you kinda need both to have meaningful checkpoints for jobs with iterations. One has to do with correctness (checkpointing strongly connected compone

Re: A question about iterations and prioritizing "control" over "data" inputs

2017-03-23 Thread Paris Carbone
Unless I got this wrong, if he meant relaxing FIFO processing per channel/stream partition then Robert is absolutely right. On 23 Mar 2017, at 12:28, Paris Carbone mailto:par...@kth.se>> wrote: I think what Theo meant is to allow for different: high/low priority on different channels (o

Re: A question about iterations and prioritizing "control" over "data" inputs

2017-03-23 Thread Paris Carbone
I think what Theo meant is to allow for different: high/low priority on different channels (or data streams per se) for n-ary operators such as ConnectedStream binary maps, loops etc.. not to change the sequence of events within channels I guess. This does not violate the FIFO channel assumptio

Re: Consistency guarantees on multiple sinks

2017-01-05 Thread Paris Carbone
Hi Nancy, Flink’s vanilla rollback recovery mechanism restarts computation from a global checkpoint thus sink duplicates (job output) can occur no matter how many sinks are declared; the whole computation in the failed execution graph will roll back. cheers Paris > On 5 Jan 2017, at 14:24,

Re: Flink Material & Papers

2016-11-21 Thread Paris Carbone
+1 for the references Imho the most relevant scientific publication related to the current state-of-the-art of Flink is the first one cited by Dominik (IEEE Bulletin). So it makes sense to cite that one. However, Hanna, if you are also interested about prior work at TU Berlin that bootstrapped

Re: Evolution algorithm on flink

2016-10-13 Thread Paris Carbone
Very interesting! Thank you for sharing Andrew! Paris > On Oct 13, 2016, at 11:00 AM, Andrew Ge Wu wrote: > > Hi guys > > I just published my code to maven central, open source ofc. > I try to make this as generic as possible. > If you are interested, please try it out, and help me to improv

Re: Data point goes missing within iteration

2016-07-20 Thread Paris Carbone
This is possibly related to the way the queue between StreamIterationTail and Head is currently implemented. I think this part is a bit prone to records loss when things get wacky and backpressure kicks in (but at least it avoids deadlocks, right?). I don’t have the time availability to look int

Re: sampling function

2016-07-12 Thread Paris Carbone
Hey Do, I think that more sophisticated samplers could make a better fit in the ML library and not in the core API but I am not very familiar with the milestones there. Maybe the maintainers of the batch ML library could check if sampling techniques could be useful there I guess. Paris > On 1

Re: flink snapshotting fault-tolerance

2016-05-19 Thread Paris Carbone
:abhis...@tetrationanalytics.com>> wrote: I was wondering how checkpoints can be async? Because your state is constantly mutating. You probably need versioned state, or immutable data structs? -Abhishek- On May 19, 2016, at 11:14 AM, Paris Carbone mailto:par...@kth.se>> wrote: Hi Stavros, Currently

Re: flink snapshotting fault-tolerance

2016-05-19 Thread Paris Carbone
e data structs? -Abhishek- On May 19, 2016, at 11:14 AM, Paris Carbone mailto:par...@kth.se>> wrote: Hi Stavros, Currently, rollback failure recovery in Flink works in the pipeline level, not in the task level (see Millwheel [1]). It further builds on repayable stream logs (i.e. Kafka), th

Re: flink snapshotting fault-tolerance

2016-05-19 Thread Paris Carbone
passes through operators you issue a warning or fail the pipeline and return an exception to the driver? On Thu, May 19, 2016 at 9:30 PM, Paris Carbone mailto:par...@kth.se>> wrote: In that case, typically a timeout invalidates the whole snapshot (all states for the same epoch) until e

Re: flink snapshotting fault-tolerance

2016-05-19 Thread Paris Carbone
You start a new checkpoint for that one? or a global new checkpoint for the rest of N tasks as well? On Thu, May 19, 2016 at 9:21 PM, Paris Carbone mailto:par...@kth.se>> wrote: Regarding your last question, If a checkpoint expires it just gets invalidated and a new complete checkpoint

Re: flink snapshotting fault-tolerance

2016-05-19 Thread Paris Carbone
. 3cp does not need assumptions i think, but engineering is more practical (it should be) and a different story in general. The [2] mentions also the assumptions... Best, Stavros On Thu, May 19, 2016 at 9:14 PM, Paris Carbone mailto:par...@kth.se>> wrote: Hi Stavros, Currently, roll

Re: flink snapshotting fault-tolerance

2016-05-19 Thread Paris Carbone
Regarding your last question, If a checkpoint expires it just gets invalidated and a new complete checkpoint will eventually occur that can be used for recovery. If I am wrong, or something has changed please correct me. Paris On 19 May 2016, at 20:14, Paris Carbone mailto:par...@kth.se

Re: flink snapshotting fault-tolerance

2016-05-19 Thread Paris Carbone
Hi Stavros, Currently, rollback failure recovery in Flink works in the pipeline level, not in the task level (see Millwheel [1]). It further builds on repayable stream logs (i.e. Kafka), thus, there is no need for 3pc or backup in the pipeline sources. You can also check this presentation [2] w

Re: FYI: Updated Slides Section

2016-04-04 Thread Paris Carbone
Some people might find my slides on the FT fundamentals from last summer interesting. If you like it feel free to include it. http://www.slideshare.net/ParisCarbone/tech-talk-google-on-flink-fault-tolerance-and-ha Paris On 04 Apr 2016, at 11:33, Ufuk Celebi mailto:u...@apache.org>> wrote: Dea

Re: How to ensure exactly-once semantics in output to Kafka?

2016-02-05 Thread Paris Carbone
This is not a bad take. It still makes a few assumptions 1) the output checkpoints the id of the last *known* ID that was *persisted* in kafka (not just pushed) 2) we assume deterministic tuple order, as Stephan pointed out On 05 Feb 2016, at 13:41, Niels Basjes mailto:ni...@basjes.nl>> wrote:

Re: How to ensure exactly-once semantics in output to Kafka?

2016-02-05 Thread Paris Carbone
you tell us more? > On 05 Feb 2016, at 13:33, Paris Carbone wrote: > > That would be good indeed. I just learned about it from Stephan mentioned. It > sounds correct to me along the lines but it would be nice to see the details. > >> On 05 Feb 2016, at 13:32, Ufuk Celebi wro

Re: How to ensure exactly-once semantics in output to Kafka?

2016-02-05 Thread Paris Carbone
That would be good indeed. I just learned about it from Stephan mentioned. It sounds correct to me along the lines but it would be nice to see the details. > On 05 Feb 2016, at 13:32, Ufuk Celebi wrote: > > >> On 05 Feb 2016, at 13:28, Paris Carbone wrote: >> >>

Re: How to ensure exactly-once semantics in output to Kafka?

2016-02-05 Thread Paris Carbone
Hi Gabor, The sinks should aware that the global checkpoint is indeed persisted before emitting so they will have to wait until they are notified for its completion before pushing to Kafka. The current view of the local state is not the actual persisted view so checking against is like relying

Re: Questions on GSoC project: Query optimisation layer for Flink Streaming

2015-03-20 Thread Paris Carbone
Hi Wepngong, This is an interesting proposal. There are indeed many streaming optimisations out there but as Gyula said we should focus on a few and engineer them in a nice way. Perhaps for the time being it makes sense to focus on a streaming job graph optimiser that basically applies optimisa