Folks,
I worked on issue https://issues.apache.org/jira/browse/IGNITE-3018 that
is related to performance of Rendezvous AF.
But Wang/Jenkins hash integer hash distribution is worse then MD5. So, i
try to use simple partition balancer close
to Fair AF for Rendezvous AF.
Take a look at the heatmaps of distributions at the issue. e.g.:
- Compare of current Rendezvous AF and new Rendezvous AF based of
Wang/Jenkins hash:
https://issues.apache.org/jira/secure/attachment/12858701/004.png
- Compare of current Rendezvous AF and new Rendezvous AF based of
Wang/Jenkins hash with partition balancer:
https://issues.apache.org/jira/secure/attachment/12858690/balanced.004.png
When the balancer is enabled the distribution of partitions by nodes
looks like close to even distribution
but in this case there is not guarantee that a partition doesn't move
from one node to another
when node leave topology.
It is not guarantee but we try to minimize it because sorted array of
nodes is used (like in for pure-Rendezvous AF).
I think we can use new fast Rendezvous AF and use 'useBalancer' flag
instead of Fair AF.
On 09.04.2017 14:12, Valentin Kulichenko wrote:
What is the replacement for FairAffinityFunction?
Generally I agree. If FairAffinityFunction can't be changed to provide
consistent mapping, it should be dropped.
-Val
On Sun, Apr 9, 2017 at 3:50 AM, Sergi Vladykin
<sergi.vlady...@gmail.com <mailto:sergi.vlady...@gmail.com>> wrote:
Guys,
It appeared that our FairAffinityFunction can assign the same
partitions to
different nodes for different caches.
It basically means that there is no collocation between the caches
at all
even if they have the same affinity.
As a result all SQL joins will not work (even collocated ones), other
operations that rely on cache collocation will be either broken or
work
slower, than expected.
All this stuff is really non-obvious. And I see no reason why we
should
allow that. I suggest to prohibit this behavior and drop
FairAffinityFunction before 2.0. We have to clearly document that
the same
affinity function must provide the same partition assignments for
all the
caches.
Also I know that Taras Ledkov was working on a decent stateless
replacement
for FairAffinity, so we should not loose anything here.
Thoughts?
Sergi
--
Taras Ledkov
Mail-To: tled...@gridgain.com
