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From Michael Han <h...@apache.org>
Subject Re: document for zk internals
Date Fri, 05 Oct 2018 03:55:15 GMT
>> which mentioned LeaderElection and FastLeaderElection.

The document here is a little bit outdated. We deprecated the old LE
implementation (LeaderElection) after 3.4.0 release, and the only leader
election in use (for both stable 3.4.x and 3.5/6) is now
FastLeaderElection. So now we only have a single LE implementation:
FastLeaderElection.

>> I want to dig into the "Leader election". Any document for it?

The best document is probably the source code itself. Also, the book
"ZooKeeper: Distributed Process Coordination" has a "ZooKeeper Internal"
section that sketches the algorithms used in FLE.

>> Another my understanding, LeaderElection and FastLeaderElection in the
"internals" doc doesn't include phase 1,2,3, right?

Yes, I think FLE is phase 0 - a preliminary phase that should be finished
before discovery / sync phase begin.

Also, it's probably worth noting that the paper "Zab: High-performance
broadcast for primary-backup systems" was talking about an older version
(pre_1.0) of ZAB. The ZAB used in 3.4 and 3.5/6 now is ZAB 1.0. We have
some documentations on the differences between these:

https://cwiki.apache.org/confluence/display/ZOOKEEPER/Zab+Pre+1.0
https://cwiki.apache.org/confluence/display/ZOOKEEPER/Zab1.0


On Thu, Oct 4, 2018 at 8:27 AM chen dongming <cademfly@hotmail.com> wrote:

> I had read 2 papers of zab. My question derive from them.
>
> <Zab: High-performance broadcast for primary-backup systems> mentioned:
>
> "Leader election occurs in two stages. First, we run a leader
> election algorithm that outputs a new process as the leader.
> We can use any protocol that, with high probability, chooses
> a process that is up and that a quorum of processes selects."
>
> But I don't think the detail of this "Leader election" is included in 2
> papers. According to my understanding, "Leader election" happen before
> phase 1,2,3 through the oracle. The paper describe phase 1,2,3 in
> detail, but not for "Leader election" and oracle.
>
> I want to dig into the "Leader election". Any document for it?
>
> Another my understanding, LeaderElection and FastLeaderElection in the
> "internals" doc doesn't include phase 1,2,3, right?
>
>
> On 2018/10/4 11:00 PM, Chris wrote:
> > You can find a lot of info if you search for Zookeeper zab protocol.
> >
> >
> http://diyhpl.us/~bryan/papers2/distributed/distributed-systems/zab.totally-ordered-broadcast-protocol.2008.pdf
> >
> >
> > http://web.stanford.edu/class/cs347/reading/zab.pdf
> >
> > Regards
> > Chris
> >
> > On 4 October 2018 4:29:21 pm chen dongming <cademfly@hotmail.com> wrote:
> >
> >> Hi,
> >>
> >> I am reading Zookeeper
> >> Internals(
> http://zookeeper.apache.org/doc/current/zookeeperInternals.html)
> >>
> >> which mentioned LeaderElection and FastLeaderElection.
> >>
> >> Is there any more document about LeaderElection and FastLeaderElection?
> >> Such as mechanism of them? Or how are they implement?
> >>
> >> Dominic
> >
> >
> >
>
>

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