Re: Question about concurrent checkpoints

Posted by Nico Kruber on
URL: http://deprecated-apache-flink-user-mailing-list-archive.369.s1.nabble.com/Question-about-concurrent-checkpoints-tp15755p15765.html

On Thursday, 21 September 2017 20:08:01 CEST Narendra Joshi wrote:

> Nico Kruber <[hidden email]> writes:
> > according to [1], even with asynchronous state snapshots (see [2]), a
> > checkpoint is only complete after all sinks have received the barriers and
> > all (asynchronous) snapshots have been processed. Since, if the number of
> > concurrent checkpoints is 0, no checkpoint barriers will be emitted until
> > the previous checkpoint is complete (see [1]), you will not get into the
> > situation where two asynchronous snapshots are being taken concurrently.
>
> Does this mean that operators would stop processing streams (because
> they received all barriers for a new checkpoint) and wait for
> the ongoing asynchronous checkpoint to complete or it means that no
> barriers would be injected into sources before checkpoint finishes?

The latter (as mentioned): no new barriers are injected into the sources.

The only thing that is waiting for asynchronous state snapshots to complete is
the checkpoint coordinator (in any case!) since a checkpoint is only complete
once all operators have stored their state. Operation continues as expected.


Nico