zookeeper-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Chris Nauroth <cnaur...@hortonworks.com>
Subject Re: Zookeeper leader not getting lock
Date Thu, 28 May 2015 18:58:02 GMT
Hello prabcs,

When you mention that "all 3 nodes try to acquire the lock", does this
mean that all 3 nodes run a ZooKeeper client process that tries to acquire
a shared lock, using something like Curator or the documented locking
recipes?

http://zookeeper.apache.org/doc/r3.4.6/recipes.html#sc_recipes_Locks


If so, then it doesn't matter whether the client process is co-located on
a machine running a leader or a follower.  Each of the 3 nodes triggers
the script independently via cron.  Therefore, the order in which these
processes start and attempt to acquire the lock is non-deterministic.  The
script co-located on the leader node might win and get the lock, or the
script co-located on one of the follower nodes might win instead.

I hope this helps.  If I misunderstood the question, please let me know.

--Chris Nauroth




On 5/28/15, 11:40 AM, "Prabhjot Bharaj" <prabhbharaj@gmail.com> wrote:

>Hi Folks,
>
>
>I have a 3 node zookeeper cluster. While working on it, I've come to
>notice
>that sometimes that lock gets acquired by the follower and the leader is
>unable to acquire the lock. I'm able to see this clearly as per the
>script's output log. This script runs as a cron on all the 3 nodes and all
>3 nodes try to acquire the lock
>
>After my script runs on all the nodes, I can see by running echo stat | nc
>localhost 2181 on all machines that the machine which has got the lock and
>ran the script successfully is a follower and not a leader.
>
>I'm thinking that the follower should not be able to get a lock. Am I
>thinking wrong somewhere ? Please point me to the correct direction.
>
>Thanks,
>
>prabcs


Mime
View raw message