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From Vikrant Singh <>
Subject Re: Query on SESSION_LOST (3.0.0)
Date Wed, 18 Nov 2015 23:29:52 GMT
Got it. Thanks for explaining it.
As I was killing  the process (assuming zookeeper removed the node), this
change will help my to save some restarts which were not needed.

On Wed, Nov 18, 2015 at 3:23 PM, Cameron McKenzie <>

> Not necessarily false alarms, just that the LOST event didn't necessarily
> mean session loss, just that curator was giving up.
> With 3.0.0 the LOST event will occur when Curator is explicitly told that
> a session has expired by Zookeeper, or if no connection to Zookeeper is
> available, Curator will publish a LOST event when it thinks that the
> session has been lost. This is based on a timer and the negotiated session
> timeout with ZooKeeper.
> On Thu, Nov 19, 2015 at 10:13 AM, Vikrant Singh <
>> wrote:
>> Thanks a lot for reply. So if I am understanding it correct, there were
>> false alarms (or mistaken connection lost) . With 3.0.0 connection_lost
>> events will happen only when there is true session lost.
>> On Wed, Nov 18, 2015 at 1:16 PM, Cameron McKenzie <
>> > wrote:
>>> Hey Vikrant,
>>> The issue was that the LOST event was being published by Curator when it
>>> gave up trying to reconnect to Zookeeper after connection loss, whereas
>>> most people were interpreting it to mean that the session was lost.
>>> So, the change in CURATOR-3.0 is that the LOST event will be published
>>> when the session has either expired and Curator is explicitly told this by
>>> Zookeeper (implying that a connection is present), or when Curator has been
>>> disconnected from Zookeeper for long enough for the session to have expired
>>> on the server (this will occur when no connection to Zookeeper is present).
>>> So, I'm not sure how it will help your case. It is just a more reliable
>>> way of knowing that the session is gone and all related ephemeral state on
>>> the Zookeeper server will also be gone.
>>> Note that it's also possible to tell Curator to use the legacy way of
>>> interpreting the LOST event.
>>> cheers
>>> On Thu, Nov 19, 2015 at 8:09 AM, Vikrant Singh <
>>>> wrote:
>>>> Hello All,
>>>> I need some guidance on understanding how to a fix done in latest
>>>> release 3.0.0 . I am talking about following fix -
>>>> .
>>>> In my project we create some ephemeral nodes and monitor a cluster
>>>> through a tree cache . Framework for treecache and ephemeral node is
>>>> created using ExponentialBackoffRetry with retry interval of 1 sec and
>>>> retry count of 29 (which is MAX_RETRIES_LIMIT ) .  We do kill the
>>>> process moment  we get TreeCacheEvent.Type.CONNECTION_LOST event .
>>>> As process restart is really expensive, I want to understand how I can
>>>> leverage from this fix.
>>>> Please help me in understanding what is the issue and how it may affect
>>>> a setup like ours. We are still not on 3.0.0.
>>>> Thanks,
>>>> Vikrant

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