On Thu, Jun 30, 2016 at 5:47 PM, Daniel Lopes <[email protected]> wrote:
> Using: > * Akka 2.4.6 project > * with cluster sharding > * Cassandra persistence > * Reactive Kafka Consumer > > Setup: > * 5 nodes > * 4 nodes consume from kafka > * 1 node in standby > * each node has cluster persistence and persistence for two other kind of > entities > * one entity is setup for 256 shard per node > * remember entities is on > * subscribing to and logging LeaderChanged cluster messages > > When performing a rolling release each node > * is brought down, > * project upgraded > * started back up > * waits 5min before moving to the next node > > The situation is that when the leader node is restarted, leadership goes > from Node 1 to Node 2 and around 10s later leadership goes back to Node 1 > again. > That is expected. The leader, that performs some of the cluster membership management tasks, is simply the node with the lowest address (sorted by host:port alphabetically) with some additional rules around membership status and reachability status. > > Can anybody tell me if this behaviour affects sharding > hand-off/rebalancing? > No. The Cluster Sharding coordinator is a Cluster Singleton that is running on the oldest node, which has nothing to do with the membership leader. When restarting the coordinator node (oldest) you should also not see much impact, because the the locations of the shards are cached on each other node when they have been in use. > Is there a way to keep leadership from flopping back and forth? > > The whole cluster slows downs during this situation and I'm concerned it > might get worse as the load grows. > What do you mean by "whole cluster slows down"? What do you observe? Cheers, Patrik > > -- > >>>>>>>>>> Read the docs: http://akka.io/docs/ > >>>>>>>>>> Check the FAQ: > http://doc.akka.io/docs/akka/current/additional/faq.html > >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user > --- > You received this message because you are subscribed to the Google Groups > "Akka User List" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at https://groups.google.com/group/akka-user. > For more options, visit https://groups.google.com/d/optout. > -- Patrik Nordwall Akka Tech Lead Lightbend <http://www.lightbend.com/> - Reactive apps on the JVM Twitter: @patriknw -- >>>>>>>>>> Read the docs: http://akka.io/docs/ >>>>>>>>>> Check the FAQ: >>>>>>>>>> http://doc.akka.io/docs/akka/current/additional/faq.html >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user --- You received this message because you are subscribed to the Google Groups "Akka User List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/akka-user. For more options, visit https://groups.google.com/d/optout.
