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From chao chu <chuchao...@gmail.com>
Subject Re: Leader Latch recovery after suspended state
Date Mon, 10 Mar 2014 14:38:45 GMT
Hi,

Just want to see if there is any progress on this?

I also have a related question about not only re-use the znode, but imho,
It would be great that LeaderLatch can survive from teomprary
ConnectionLossException (i.e., due to transient network issue).

I guess in most cases, the context switch due to leader re-election is
quite expensive, we might not want to do that just because of some
transient issue. if the current leader can re-connect within the session
timeout, it should still hold the leadership and no leader change would
happen during between. The similar rational like the differences between
ConnestionLossException (which is recoverable) and SessionExipredException
(which is not recoverable).

what are your thoughts on this? Thanks a lot!

Regards,


On Wed, Aug 21, 2013 at 2:05 AM, Jordan Zimmerman <
jordan@jordanzimmerman.com> wrote:

> Yes, I was suggesting how to patch Curator.
>
> On Aug 20, 2013, at 10:59 AM, Calvin Jia <jia.calvin@gmail.com> wrote:
>
> Currently this is not supported in the Curator library, but the Curator
> library (specifically leader latch's reset method) is the correct/logical
> place to add this feature if I want it?
>
>
> On Tue, Aug 20, 2013 at 10:34 AM, Jordan Zimmerman <
> jordan@jordanzimmerman.com> wrote:
>
>> On reset() it could check to see if its node still exists. It would make
>> the code a lot more complicated though.
>>
>> -JZ
>>
>> On Aug 20, 2013, at 10:25 AM, Calvin Jia <jia.calvin@gmail.com> wrote:
>>
>> A leader latch enters the suspended state after failing to receive a
>> response from the first ZK machine it heartbeats to (takes 2 thirds of the
>> timeout). For the last 1 third, it tries to contact another ZK machine. If
>> it is successful, it will enter the state reconnected.
>>
>> However, on reconnect, despite the fact the original node it created in
>> ZK is still there, it will create another ephemeral-sequential node (the
>> reset method is called). This means it will relinquish leadership, if there
>> is another machine with a latch in the same path.
>>
>> Is there any way to reconnect and reuse the original ZK node?
>>
>> Thanks!
>>
>>
>>
>
>


-- 
ChuChao

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