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Subject: RE: Possible issue with cluster availability following new Leader
 Election - ZK 3.4
Date: Thu, 10 May 2012 12:20:01 +0100
Message-ID: <26D6F1977403764E8B5C4B26F9430E0A0FA2E5EE@NLDNC108PEX1.ubsw.net>
In-Reply-To: 
 <CAOYeBnN8Dsgk7C8yjnDQJ-E4KHKNc6L58R+Q5DLw0auBbMOmzw@mail.gmail.com>
Thread-Topic: Possible issue with cluster availability following new Leader
 Election - ZK 3.4
Thread-Index: Ac0uB8BQVl2nwe0jRLiOv/Prj2fccQAiuleQ
References: <26D6F1977403764E8B5C4B26F9430E0A0FA2E277@NLDNC108PEX1.ubsw.net>
 <CAOYeBnN8Dsgk7C8yjnDQJ-E4KHKNc6L58R+Q5DLw0auBbMOmzw@mail.gmail.com>
From: <Alexandar.Gvozdenovic@ubs.com>
To: <user@zookeeper.apache.org>

I think there may be a problem here with the 3.4 branch. I dropped the
cluster back to 3.3.5 and the behaviour was much better.

To summarize:

650mb of data=20
20k nodes of varied size
3 node cluster

On 3.4.x (using latest branch build)
---------
Takes 3-4 minutes to bring up a cluster from cold
Takes 40-50 secs to recover from a leader failure
Takes 10 secs for a new follower to join the cluster

On 3.3.5
--------
Takes 10-20 secs to bring up a cluster from cold
Takes 10 secs to recover from a leader failure
Takes 10 secs for a new follower to join the cluster

Any views on this from the ZK devs? The differences in behaviour only
start becoming apparent as the dataset gets bigger.=20
I was hoping to use 3.4 for the transactional features it offered via
the 'multi-update' operations, but this issue seems pretty serious...


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