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From kamel.zaaro...@gmail.com
Subject Re: out of order callbacks of events in ZK
Date Fri, 06 Nov 2015 20:50:16 GMT
Thanks you for your reply.

In that case is there a standard solution to synchronize different clients? 
If ordered changes to ZK might be seen out of order with certain clients, then what is the
standard way to synchronize clients?



> On Nov 6, 2015, at 3:41 PM, Chris Nauroth <cnauroth@hortonworks.com> wrote:
> 
> 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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