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From Ludwig Pummer <ludwigp-zookee...@chip-web.com>
Subject Re: Reconnection with expired session
Date Wed, 12 Nov 2014 02:19:15 GMT
You are confounding your expired session testing with the wiping of all 
ZK data behind the scene.

I seem to recall something about the client refusing to reconnect to a 
ZK server that does not have at least the Zxid it last saw. Though it's 
bad for your particular case, it's a good thing in general since it 
prevents the client from connecting to a quorum member which isn't up to 
date.

On 11/11/2014 6:08 PM, Cameron McKenzie wrote:
> Guys,
> I have a (possibly somewhat contrived) issue relating to reconnection of a
> client to ZK after quorum has been lost, and data has been corrupted.
>
> Essentially this is what's happening:
> -Client connects to 3 node ZK cluster
> -Client writes some ephemeral zNodes etc.
> -All nodes in ZK cluster are shut down
> -Contents of data/version-2 directories are removed on each ZK instance
> (i.e. the acceptedEpoch, currentEpoch and all the snapshots and tran logs)
> -Restart the nodes in the ZK cluster
>
> At this point, the ZK cluster comes up fine, but the client will not
> automatically reconnect. Having stepped through the client code with a
> debugger it seems like the server just doesn't respond to the session
> initialisation request). These are the logs, which are repeated every
> second. Note that if I restart the client, everything's fine.
>
> 12:56:35.978 [main-SendThread(ubuntubox:2181)] INFO
> org.apache.zookeeper.ClientCnxn - Opening socket connection to server
> ubuntubox/192.168.56.102:2181. Will not attempt to authenticate using SASL
> (unknown error)
> 12:56:35.980 [main-SendThread(ubuntubox:2181)] INFO
> org.apache.zookeeper.ClientCnxn - Socket connection established to
> ubuntubox/192.168.56.102:2181, initiating session
> 12:56:35.983 [main-SendThread(ubuntubox:2181)] DEBUG
> org.apache.zookeeper.ClientCnxn - Session establishment request sent on
> ubuntubox/192.168.56.102:2181
> 12:56:36.002 [main-SendThread(ubuntubox:2181)] INFO
> org.apache.zookeeper.ClientCnxn - Unable to read additional data from
> server sessionid 0x249a1b64cc90000, likely server has closed socket,
> closing socket connection and attempting reconnect
> 12:56:37.833 [main-SendThread(ubuntubox:2182)] INFO
> org.apache.zookeeper.ClientCnxn - Opening socket connection to server
> ubuntubox/192.168.56.102:2182. Will not attempt to authenticate using SASL
> (unknown error)
> 12:56:37.834 [main-SendThread(ubuntubox:2182)] INFO
> org.apache.zookeeper.ClientCnxn - Socket connection established to
> ubuntubox/192.168.56.102:2182, initiating session
> 12:56:37.835 [main-SendThread(ubuntubox:2182)] DEBUG
> org.apache.zookeeper.ClientCnxn - Session establishment request sent on
> ubuntubox/192.168.56.102:2182
> 12:56:37.859 [main-SendThread(ubuntubox:2182)] INFO
> org.apache.zookeeper.ClientCnxn - Unable to read additional data from
> server sessionid 0x249a1b64cc90000, likely server has closed socket,
> closing socket connection and attempting reconnect
> 12:56:38.298 [main-SendThread(ubuntubox:2183)] INFO
> org.apache.zookeeper.ClientCnxn - Opening socket connection to server
> ubuntubox/192.168.56.102:2183. Will not attempt to authenticate using SASL
> (unknown error)
> 12:56:38.299 [main-SendThread(ubuntubox:2183)] INFO
> org.apache.zookeeper.ClientCnxn - Socket connection established to
> ubuntubox/192.168.56.102:2183, initiating session
> 12:56:38.300 [main-SendThread(ubuntubox:2183)] DEBUG
> org.apache.zookeeper.ClientCnxn - Session establishment request sent on
> ubuntubox/192.168.56.102:2183
>
> Can someone explain what's going on? Is this a bug? While I understand that
> it's slightly contrived, the destruction of the data is certainly a
> possibility, and having to restart every client even when the cluster comes
> back up is not ideal.
> cheers
> Cam
>


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