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From Erick Erickson <erickerick...@gmail.com>
Subject Re: killing a Solr instance leaves the state in Zookeeper "active"
Date Fri, 23 Oct 2015 17:55:06 GMT
Not so much a problem as behavior I wasn't fully expecting. It does
seem a little trappy to have this thing that's supposed to be the
state of the collection but then require that another znode be
checked to see if state.json is telling the truth.

In the particular case that came up, a monitoring system was trying
to generate alerts when a node went down by relying on the state.json
znode, but no alert was being generated in this case.

BTW, this is 4.6, I suspect the eventual answer is to upgrade and
use the collections API CLUSTERSTATUS...

I don't have strong feelings about this, mostly throwing it out for
discussion. I suppose the goal here is to keep any client from having
to directly look at the state.json file and provide APIs that conceal
this kind of thing.

Your point about the complexity of publishing state for other nodes
is well taken...


On Fri, Oct 23, 2015 at 10:29 AM, Shalin Shekhar Mangar
<shalinmangar@gmail.com> wrote:
> This is expected and works as designed. We have enough complexity in
> publishing state for other nodes (LIR) and we shouldn't add any more.
> Besides what if the leader itself was killed, who changes the state
> then?
>
> What problem are you trying to solve?
>
> On Fri, Oct 23, 2015 at 10:19 PM, Erick Erickson
> <erickerickson@gmail.com> wrote:
>> If I kill a replica with -9, the state.json node never gets updated,
>> the node shows as "active"
>>
>> There is code around that checks the live_nodes to see whether the
>> state.json node can be believed, and Varun pointed me at Solr JIRAs
>> for making sure CLUSTERSTATUS consults live_nodes, indicating that
>> this is something that's expected. But it seems trappy.
>>
>> My question is whether it's worth raising a JIRA. The leader could
>> notice a mismatch and update state.json or something like that.
>>
>> I'll raise a JIRA if it seems like something that should be discussed.
>>
>> Let me know,
>> Erick
>>
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>
>
>
> --
> Regards,
> Shalin Shekhar Mangar.
>
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