ZookeeperMatt @ JCConf 2016

About me

methodho@gmail.com

https://github.com/methodho

https://www.facebook.com/evermatt

mailto:methodho@gmail.comhttps://github.com/methodhohttps://www.facebook.com/evermatthttp://www.softleader.com.tw/

ZooKeeper

ZooKeeper

Java programming to ZooKeeper

o.a.z.ZooKeeper (3.4.9)

o.a.c.f.r.l.LeaderLatch (2.11.0)

Because coordinating distributed systems is a Zoo

Apache ZooKeeper wiki

WHAT IS ZOOKEEPER

https://zookeeper.apache.org/doc/current/zookeeperOver.html

WHAT IS ZOOKEEPER

https://zookeeper.apache.org/doc/current/zookeeperOver.html

server

/bin/zkServer.sh start

zookeeper server

/bin/zkCli.sh [-server localhost:2181]

server

/bin/zkServer.sh stop

ZOOKEEPER CLI

znode

create [-s] [-e] path data

znode

delete path

rmr path

ZOOKEEPER CLI

znode children

ls path [watch]

ls2 path [watch]

znode data (byte[])

set path data [watch]

get path [watch]

ZOOKEEPER CLI

CLIENT

CLIENT

CLIENTZooKeeperServer

ZOOKEEPER WATCH

ZOOKEEPER WATCH

CLIENT

CLIENT

CLIENTZooKeeperServer

watch

watch

watch

ZOOKEEPER WATCH

CLIENT

CLIENT

CLIENT

Server

ZooKeeperServer

watch

watch

watch

Event

Triggered

A MCV EXAMPLE (MODEL 2)

Controller(Servlet/Filter)

View(JSP)

Model(JavaBean)

^_^

...?

BEFORE ZOOKEEPER

ap

hardcode

properties

passes argument ...

cons?

AP1

(run=false)

AP3

(run=false)

AP2

(run=true)

BEFORE ZOOKEEPER

ap

db table control

db lock

cons?

AP1 AP3AP2

DB

runbyAP2

BEFORE ZOOKEEPER

:

...

https://zookeeper.apache.org/doc/trunk/recipes.html

BEFORE ZOOKEEPER

ZooKeeper Recipes!

https://zookeeper.apache.org/doc/trunk/recipes.html

https://zookeeper.apache.org/doc/trunk/recipes.html#sc_leaderElection

LEADER ELECTION

ZookeeperServer

/

/SOME-PATH

/ZNODE_1

CLIENT_1 /ZNODE_2

CLIENT_2

/ZNODE_3

CLIENT_3

A simple way:

Use SEQUENCE & EPHEMERAL znode

https://zookeeper.apache.org/doc/trunk/recipes.html#sc_leaderElection

https://zookeeper.apache.org/doc/trunk/recipes.html#sc_leaderElection

LEADER ELECTION

ZookeeperServerAdvance solution

/

/SOME-PATH

https://zookeeper.apache.org/doc/trunk/recipes.html#sc_leaderElection

https://zookeeper.apache.org/doc/trunk/recipes.html#sc_leaderElection

LEADER ELECTION

ZookeeperServer

/

/SOME-PATH

/ZNODE_1

CLIENT_1

Advance solution

https://zookeeper.apache.org/doc/trunk/recipes.html#sc_leaderElection

https://zookeeper.apache.org/doc/trunk/recipes.html#sc_leaderElection

LEADER ELECTION

ZookeeperServer

/

/SOME-PATH

/ZNODE_1

CLIENT_1 /ZNODE_2

CLIENT_2

Advance solution

https://zookeeper.apache.org/doc/trunk/recipes.html#sc_leaderElection

https://zookeeper.apache.org/doc/trunk/recipes.html#sc_leaderElection

LEADER ELECTION

ZookeeperServer

/

/SOME-PATH

/ZNODE_1

CLIENT_1 /ZNODE_2

CLIENT_2

/ZNODE_3

CLIENT_3

Advance solution

https://zookeeper.apache.org/doc/trunk/recipes.html#sc_leaderElection

IMPLEMENTING LEADER ELECTION

Start(1)

Connecttozookeeperserver

(2)Createparentifnot

exist(3)

Create-e-snodez

Nodejfound

End(6)

Youareleader

(7)Watchfornodej

Y

N

(5)Findnodej,wherejisthelargestseq

andj