ignite-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Alexei Scherbakov <alexey.scherbak...@gmail.com>
Subject Re: Getting rid of NONE cache rebalance mode
Date Wed, 22 Jul 2020 06:39:04 GMT
Ivan,
My opinion the ASYNC rebalancing is a best approach for off-loading 3-d
party store, and it provides consistency.

+1 for deprecation of NONE in the next release - ignore NONE and use ASYNC
instead
For those who require absence of rebalancing for some reason still be
possible to use rebalanceDelay=infinity.

+1 for removal of rebalanceMode in 3.0.
Note what we still require SYNC logic internally for system cache in some
places.



вт, 21 июл. 2020 г. в 15:59, Ivan Pavlukhin <vololo100@gmail.com>:

> Alexey,
>
> Thank you for explanation. I feel that I miss a couple bits to
> understand the picture fully. I am thinking about a case which I tend
> to call a Memcached use-case. There is a cache over underlying storage
> with read-through and expiration and without any rebalancing at all.
> When new nodes enter they take ownership for some partitions from
> already running nodes and serve client requests. Entries for not
> owning anymore partitions expire according to configuration.
>
> Actually, I have an idea. My guess is that "rebalancing" is a smarter
> and better approach than waiting for expiration. Am I right?
>
> 2020-07-21 15:31 GMT+03:00, Alexey Goncharuk <alexey.goncharuk@gmail.com>:
> > Ivan,
> >
> > In my understanding this mode does not work at all even in the presence
> of
> > ForceKeysRequest which is now supposed to fetch values from peers in case
> > of a miss. In this mode we 1) move partitions to OWNING state
> > unconditionally, and 2) choose an arbitrary OWNING node for force keys
> > request. Therefore, after a user started two additional nodes in a
> cluster,
> > the request may be mapped to a node which does not hold any data. We will
> > do a read-through in this case, but it will result in significant load
> > increase on a third-party storage right after a node started, which means
> > that adding a node will increase, not decrease, the load on the database
> > being cached.
> > All these issues go away when (A)SYNC mode is used.
> >
> > Val,
> > The idea makes sense to me - a user can use rebalance future to wait for
> > rebalance to finish. This will simplify the configuration even further.
> >
> > пн, 20 июл. 2020 г. в 21:27, Valentin Kulichenko <
> > valentin.kulichenko@gmail.com>:
> >
> >> +1 for deprecating/removing NONE mode.
> >>
> >> Alexey, what do you think about the SYNC mode? In my experience, it does
> >> not add much value as well. I would go as far as removing the
> >> rebalancingMode parameter altogether (probably in 3.0).
> >>
> >> -Val
> >>
> >> On Mon, Jul 20, 2020 at 11:09 AM Ivan Pavlukhin <vololo100@gmail.com>
> >> wrote:
> >>
> >> > Alexey, Igniters,
> >> >
> >> > Could you please outline motivation answering following questions?
> >> > 1. Does this mode generally work correctly today?
> >> > 2. Can this mode be useful at all?
> >> >
> >> > I can imagine that it might be useful in a transparent caching use
> >> > case (if I did not misunderstand).
> >> >
> >> > 2020-07-20 20:39 GMT+03:00, Pavel Tupitsyn <ptupitsyn@apache.org>:
> >> > > +1
> >> > >
> >> > > More evidence:
> >> > >
> >> >
> >>
> https://stackoverflow.com/questions/62902640/apache-ignite-cacherebalancemode-is-not-respected-by-nodes
> >> > >
> >> > > On Mon, Jul 20, 2020 at 8:26 PM Alexey Goncharuk
> >> > > <alexey.goncharuk@gmail.com>
> >> > > wrote:
> >> > >
> >> > >> Igniters,
> >> > >>
> >> > >> I would like to run the idea of deprecating and probably ignoring
> >> > >> the
> >> > >> NONE
> >> > >> rebalance mode by the community. It's in the removal list for
> Ignite
> >> 3.0
> >> > >> [1], but it looks like it still confuses and creates issues for
> >> > >> users
> >> > >> [2].
> >> > >>
> >> > >> What about deprecating it in one of the next releases and even
> >> ignoring
> >> > >> this constant in further releases, interpreting it as ASYNC, before
> >> > >> Ignite
> >> > >> 3.0? I find it hard to believe that any Ignite user actually has
> >> > >> RebalanceMode.NONE set in their configuration due to its absolutely
> >> > >> unpredictable behavior.
> >> > >>
> >> > >> Thanks for your thoughts,
> >> > >> --AG
> >> > >>
> >> > >> [1]
> >> > >>
> >> > >>
> >> >
> >>
> https://cwiki.apache.org/confluence/display/IGNITE/Apache+Ignite+3.0+Wishlist
> >> > >> [2]
> >> > >>
> >> > >>
> >> >
> >>
> http://apache-ignite-developers.2346864.n4.nabble.com/About-Rebalance-Mode-SYNC-amp-NONE-td47279.html
> >> > >>
> >> > >
> >> >
> >> >
> >> > --
> >> >
> >> > Best regards,
> >> > Ivan Pavlukhin
> >> >
> >>
> >
>
>
> --
>
> Best regards,
> Ivan Pavlukhin
>


-- 

Best regards,
Alexei Scherbakov

Mime
  • Unnamed multipart/alternative (inline, None, 0 bytes)
View raw message