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From Semyon Boikov <sboi...@gridgain.com>
Subject Re: Resurrect FairAffinityFunction
Date Tue, 25 Jul 2017 08:07:43 GMT

As far as I know in 2.0 some changes were made in rendezvous function so
now it can provide better result. Do you have some numbers for 2.0 so that
we can compare rendezvous and fair affinity functions?


On Tue, Jul 25, 2017 at 5:13 AM, <dsetrakyan@apache.org> wrote:

> Agree with Val, we should bring it back.
> ⁣D.​
> On Jul 24, 2017, 8:14 PM, at 8:14 PM, Valentin Kulichenko <
> valentin.kulichenko@gmail.com> wrote:
> >Guys,
> >
> >Some time ago we removed FairAffinityFunction from the project.
> >However, my
> >communication with users clearly shows that is was a rush decision.
> >Distribution showed by Fair AF is much better than default and for some
> >users it's extremely important. Basically, there are cases when
> >rendezvous
> >function is no-go.
> >
> >The reason for removal was that it was possible to get inconsistent
> >results
> >in case multiple caches were created on different topologies. However,
> >I
> >think this is fixable. As far as I understand, the only thing we need
> >to do
> >is to maintain a single AffinityFunctionContext for all the caches with
> >same affinity function. Currently for each cache we have separate
> >context
> >which holds the state used by Fair AF. If the state is different, we
> >have
> >an issue.
> >
> >The only question is how to check whether two functions are the same or
> >not. In case both cache node filter and backup filter are not
> >configured,
> >this is easy - if number of partitions and excludeNeighbors flag are
> >equal
> >for two functions, these functions are also equal.
> >
> >With filters it's a bit more complicated as these are custom
> >implementations and in general case we don't know how to compare them.
> >Although, to solve this problem, we can enforce user to implement
> >equals()
> >method for these implementation if Fair AF is used.
> >
> >I propose to make changes described above and bring Fair AF back.
> >
> >Thoughts?
> >
> >-Val

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