lets break it into two parts. Update to ExternalView is done by the controller. The clients are notified of the change through a Zookeeper callback. Its not guaranteed that all clients will receive the callback at the same time.
In general, its not a good idea to rely on every client seeing the same view at the same time (its impossible to achieve this in a distributed system). However, it is the view is timeline consistent. For e.g if controller changes the external view to EV(t1), EV(t2), EV(t3) the clients will get notified in the same order. Another thing you should be aware is that if these changes happen in quick succession, its possible that the client only sees EV(t1) and EV(t3). Can you provide more details on what you are planning to achieve. We can suggest the right design. On Fri, Nov 10, 2017 at 4:05 AM, Xue Junkai <[email protected]> wrote: > If you attach the external view listener through HelixManager, all the > listener will be notified at same time. > > On Fri, Nov 10, 2017 at 4:02 AM, leela maheswararao < > [email protected]> wrote: > > > Team,Does helix ensure whether all clients see same external view at same > > time ? Or application should handle this? > > > > Regards,Mahesh > > > > > -- > Junkai Xue >
