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Zookeeper >> mail # user >> help regarding zookeeper watches


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Prasad GS 2013-07-08, 12:11
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Chris Brinley 2013-07-08, 12:25
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Prasad GS 2013-07-08, 13:10
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Ted Dunning 2013-07-08, 14:21
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Ben Bangert 2013-07-19, 01:42
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Re: help regarding zookeeper watches
I think the passive voice confuses things here. It says "are sent," but not anything about who does the sending.

Of course you are correct that if the connection is down, the zk server cannot send a notification. It's the client that detects this. Nothing is sent by the server.

-m

On Jul 8, 2013, at 6:10 AM, Prasad GS <[EMAIL PROTECTED]> wrote:

> Any idea about #1 : When the connection is not available, how can zookeeper
> send session events to outstanding watch handlers?
>
>
> On Mon, Jul 8, 2013 at 5:55 PM, Chris Brinley <[EMAIL PROTECTED]
>> wrote:
>
>> Your local client detects session drop. That is tcp connection lost. By
>> safe mode all that is meant is that your application should take action to
>> deal with this new state (I. E. No connection to zookeeper cluster). In
>> this mode it may not be advisable to handle new requests or allow
>> configuration changes. This depends on the rules of the problem domain if
>> course.
>> ________________________________________
>> From: Prasad GS [[EMAIL PROTECTED]]
>> Sent: Monday, July 08, 2013 7:11 AM
>> To: [EMAIL PROTECTED]
>> Subject: help regarding zookeeper watches
>>
>> Hi,
>>
>> As per the zookeeper programmers guide regarding watches,
>>
>> "When you disconnect from a server (for example, when the server fails),
>> you will not get any watches until the connection is reestablished. For
>> this reason session events are sent to all outstanding watch handlers. Use
>> session events to go into a safe mode: you will not be receiving events
>> while disconnected, so your process should act conservatively in that mode"
>>
>> We have couple of questions here :
>>
>> 1.  When the connection is not available, how can zookeeper send session
>> events to outstanding watch handlers?
>> 2.  Can someone please elaborate the safe mode & the steps that needs to be
>> done in that mode
>>
>> Regards,
>> Skanda
>>
NEW: Monitor These Apps!
elasticsearch, apache solr, apache hbase, hadoop, redis, casssandra, amazon cloudwatch, mysql, memcached, apache kafka, apache zookeeper, apache storm, ubuntu, centOS, red hat, debian, puppet labs, java, senseiDB