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From Pavel Tupitsyn <ptupit...@apache.org>
Subject Re: Best Effort Affinity for thin clients
Date Thu, 14 Jun 2018 13:17:56 GMT
Ok, I see, this is what I was trying to understand, and this is an
important note I think:

* We should request AffinityFunction for each particular cache and only
enable this functionality for known functions
* Make sure that known server-side functions never change their behavior

Thanks

On Thu, Jun 14, 2018 at 3:39 PM, Igor Sapego <isapego@apache.org> wrote:

> Vladimir is right,
>
> As far as I know, most users use affinity functions provided by Ignite.
> So we could optimize for the default case and, in future, optionally,
> let user implement their own AffinityFunction for thin clients.
>
> Best Regards,
> Igor
>
>
> On Thu, Jun 14, 2018 at 3:06 PM Vladimir Ozerov <vozerov@gridgain.com>
> wrote:
>
> > Pavel,
> >
> > The idea here is that optimization will be applicable only for well-known
> > affinity functions. E.g., we know that for rendezvous affinity, partition
> > is "hash(key) % partitions". This is all we need to make default affinity
> > work.
> >
> > On Thu, Jun 14, 2018 at 11:41 AM, Pavel Tupitsyn <ptupitsyn@apache.org>
> > wrote:
> >
> > > AffinityFunction interface has the following method:
> > > int partition(Object key)
> > >
> > > User calls cache.put(x,y) from the client.
> > >
> > > In order to calculate the target node we have to call that partition
> > > method,
> > > and then use partition map to get the node by partition.
> > >
> > > But client does not have AffinityFunction.
> > > Where am I wrong here?
> > >
> > > On Thu, Jun 14, 2018 at 10:26 AM, Igor Sapego <isapego@gridgain.com>
> > > wrote:
> > >
> > > > Denis, that's right.
> > > >
> > > > Best Regards,
> > > > Igor
> > > >
> > > >
> > > > On Wed, Jun 13, 2018 at 10:58 PM Denis Magda <dmagda@apache.org>
> > wrote:
> > > >
> > > > > Pavel,
> > > > >
> > > > > Most likely the client will be pulling the partitioning map
> > > periodically.
> > > > > If the local map is outdated, it won't be a big deal because a
> server
> > > > node
> > > > > that receives a request:
> > > > >
> > > > >    - can redirect it to a map that owns a partition
> > > > >    - will add an updated partition map to the client's response or
> > will
> > > > >    turn a special flag in the response suggesting the client do
> that
> > > > > manually.
> > > > >
> > > > > Igor, is this what you're suggesting?
> > > > >
> > > > > --
> > > > > Denis
> > > > >
> > > > > On Wed, Jun 13, 2018 at 11:31 AM Pavel Tupitsyn <
> > ptupitsyn@apache.org>
> > > > > wrote:
> > > > >
> > > > > > Hi Igor,
> > > > > >
> > > > > > How can we invoke the affinity function on the client, if we
> don't
> > > have
> > > > > the
> > > > > > implementation at hand?
> > > > > > Am I missing something?
> > > > > >
> > > > > > Thanks,
> > > > > > Pavel
> > > > > >
> > > > > >
> > > > > > On Wed, Jun 13, 2018 at 5:34 PM, Igor Sapego <isapego@apache.org
> >
> > > > wrote:
> > > > > >
> > > > > > > Hi, Igniters,
> > > > > > >
> > > > > > > Currently, I'm working on the thin C++ client implementation.
> > > > > > > As you may already know, there is an issue with latency
in our
> > > > > > > thin clients, which also can result in performance issues
(you
> > > > > > > can see the "About Ignite Thin client performance" thread
on
> > > > > > > user list).
> > > > > > >
> > > > > > > So, how about we implement some kind of "Best Effort Affinity"
> > > > > > > for our thin clients? In my opinion, this could be possible
and
> > > > > > > may improve mean latency when using thin clients dramatically.
> > > > > > >
> > > > > > > The scenario is following:
> > > > > > > 1. Thin client connects to one of the node from the provided
> > > > > > > address list, just as now.
> > > > > > > 2. When user create instance of CacheClient, thin client
> > > > > > > requests partition mapping for the cache.
> > > > > > > 3. Client establishes connections to nodes, which are both
in
> the
> > > > > > > list, provided by user and in a server node response.
> > > > > > > 4. When user makes put/get/some other cache operation,
> > > > > > > thin client makes the best effort to send the request to
the
> > node,
> > > > > > > which stores the data.
> > > > > > > 5. To update partition mapping, thin client can provide
public
> > API,
> > > > > > > or do it with some timeout. Also, we can add "miss" flag
to
> cache
> > > > > > > operation response, which whill indicate, that operation
was
> not
> > > > > > > local for the server node and which thin client can use
to
> > > > > > > understand, that partition mapping has changed to request
> server
> > > > > > > node for an update.
> > > > > > >
> > > > > > > What do you think?
> > > > > > >
> > > > > > > Best Regards,
> > > > > > > Igor
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>

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