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From Chris Nauroth <cnaur...@hortonworks.com>
Subject Re: out of order callbacks of events in ZK
Date Fri, 06 Nov 2015 20:41:22 GMT
Hello Kamel,

The behavior you're seeing is not at odds with ZooKeeper's guarantees.
For more details, please refer to the ZooKeeper programmer's guide
statements on consistency guarantees.

http://zookeeper.apache.org/doc/r3.4.6/zookeeperProgrammers.html#ch_zkGuara
ntees


In particularly, note the sidebar describing how ZooKeeper does not
guarantee simultaneously consistent cross-client views.

--Chris Nauroth




On 11/6/15, 12:32 PM, "kamel zaarouri" <kamel.zaarouri@gmail.com> wrote:

>Hi zk-users,
>
>Assume this tree:
>
>
>parent1
>|         |____Child1
>|
>|
>parent2
>         |_____<empty>
>
>
>I have 1 watchers on parent1 and another watcher on parent2. I have those
>watchers setup to receive updates of the child nodes of both parents.
>
>Child1 is a non-ephemeral node.
>
>If another client:
>
>- Creates an ephemeral node (let's call it ephem2) under parent2
>then and only then it
>- Updates Child1
>
>What I am seeing now is that 20% of the time, I receive the callbacks out
>of order, i.e. I see the Child1 being updated before ephem2 is seen
>created.
>
>Is this is a bug in the client I am using or does ZK not guarantee order
>in
>this way?
>
>Thank you!,


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