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From Stephan Ewen <se...@apache.org>
Subject Re: Checkpoint state stored in backend, and deleting old checkpoint state
Date Wed, 06 Apr 2016 09:39:10 GMT
Hi Zach!

I am working on incremental checkpointing, hope to have it in the master in
the next weeks.

The current approach is a to have a full self-contained checkpoint every
once in a while, and have incremental checkpoints most of the time. Having
a full checkpoint every now and then spares you from re-applying an endless
set of deltas on recovery.

Related to that is also making the checkpointing asynchronous, so that
normal operations do not see any disruption any more.

Greetings,
Stephan

On Tue, Apr 5, 2016 at 10:25 PM, Zach Cox <zcox522@gmail.com> wrote:

> Thanks for the details Konstantin and Ufuk!
>
>
> On Tue, Apr 5, 2016 at 2:39 PM Konstantin Knauf <
> konstantin.knauf@tngtech.com> wrote:
>
>> Hi Ufuk,
>>
>> I thought so, but I am not sure when and where ;) I will let you know,
>> if I come across it again.
>>
>> Cheers,
>>
>> Konstantin
>>
>> On 05.04.2016 21:10, Ufuk Celebi wrote:
>> > Hey Zach and Konstantin,
>> >
>> > Great questions and answers. We can try to make this more explicit in
>> the docs.
>> >
>> > On Tue, Apr 5, 2016 at 8:54 PM, Konstantin Knauf
>> > <konstantin.knauf@tngtech.com> wrote:
>> >> To my knowledge flink takes care of deleting old checkpoints (I think
>> it
>> >> says so in the documentation about savepoints.). In my experience
>> >> though, if a job is cancelled or crashes, the checkpoint files are
>> >> usually not cleaned up. So some housekeeping might be necessary.
>> >
>> > Regarding cleanup: currently only the latest successful checkpoint is
>> retained.
>> >
>> > On graceful shutdown, all checkpoints should be cleaned up as far as I
>> > know. Savepoints always have to be cleaned up manually.
>> >
>> > On crashes, the checkpoint state has to be cleaned up manually (if the
>> > JVM shut down hooks did not run).
>> >
>> > @Konstantin: did you have lingering state without crashes?
>> >
>> > – Ufuk
>> >
>>
>> --
>> Konstantin Knauf * konstantin.knauf@tngtech.com * +49-174-3413182
>> TNG Technology Consulting GmbH, Betastr. 13a, 85774 Unterföhring
>> Geschäftsführer: Henrik Klagges, Christoph Stock, Dr. Robert Dahlke
>> Sitz: Unterföhring * Amtsgericht München * HRB 135082
>>
>

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