Semyon, We had some improvements, but to knowledge fair affinity still provides much better distribution (at least I haven't seen any results showing otherwise). Please correct me if I'm wrong.
Actually, I think it's not an issue with fair function in particular, but rather a design flow in affinity manager. The exact same issue will exist not only with fair function, but with ANY function that uses AffinityFunctionContext#previousAssignment to calculate assignments. And the context is provided from the outside, function has nothing to do with it. So let's fix the root cause and bring innocent FairAF back :) -Val On Tue, Jul 25, 2017 at 1:07 AM, Semyon Boikov <sboi...@gridgain.com> wrote: > Valentin, > > 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? > > Thanks > > On Tue, Jul 25, 2017 at 5:13 AM, <dsetrak...@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.kuliche...@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 > > >
