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Kafka >> mail # dev >> zkclient dies after UnknownHostException in zk reconnect


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Re: zkclient dies after UnknownHostException in zk reconnect
> node loss. Did the Kafka consumer not respond to rebalance events or did
> the server not respond to state change events ? Also, ephemeral nodes are
> lost only when sessions are expired on the zookeeper server or if clients
> close the session actively, how does losing connection lead to ephemeral
> node loss?

My understanding of Anatoly's observation is that on session
expiration, zkclient will reconnect
(https://github.com/sgroschupf/zkclient/blob/master/src/main/java/org/I0Itec/zkclient/ZkClient.java#L458)
but if the connect causes an IOException, that would effectively mean
that the session will not get re-established. Anatoly, can you
confirm?

> On Mon, Sep 23, 2013 at 7:02 AM, Anatoly Fayngelerin <[EMAIL PROTECTED]>wrote:
>
>> Hi Everyone,
>>
>> I've run into the following issue with the Kafka server. The zkclient lib
>> seems to die silently if there is an UnknownHostException(or any
>> IOException) while reconnecting the ZK session. I've filed a bug about this
>> with the zkclient lib(https://github.com/sgroschupf/zkclient/issues/23).
>> The
>> ramifications for Kafka were the silent loss of all ephemeral nodes
>> associated with the affected process.
>>
>> Has anyone faced this issue? If so, what is the recommended way of dealing
>> with this?
>>
>> If there is no good solution available, would the community be open to a
>> patch that periodically verifies ZK connectivity?
>>
>> Thanks,
>> Anatoly
>>