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From Daniel Collins <>
Subject Re: clusterstate.json does not reflect current state of down versus active
Date Wed, 16 Apr 2014 18:53:45 GMT
We actually have a similar scenario, we have 64 cores per machine, and even
that sometimes has issues when we shutdown all cores at once.  We did start
to write a "force election for Shard X" tool but it was harder than we
expected, its still on our to-do list.

Some context, we run 256 shards spread over 4 machines, and several Solr
instances per machine (16 cores per instance, 4 instances per machine).
 Our machines regularly go down for maintenance, and shutting down the Solr
core closes the HTTP interface (at Jetty level) before any of Solr gets to
do its shutdown sequence: publishing as down, election, etc.  Since we run
an NRT system, that causes all kinds of backlogs in the indexing pipeline
whilst Solr queues up indexing requests waiting for a valid leader...
 Hence the need for an API to move leadership off the instance, *before* we
begin shutdown.

Any insight would be appreciated, we are happy to contribute this back if
we can get it working!

On 16 April 2014 15:49, Shawn Heisey <> wrote:

> On 4/16/2014 8:02 AM, Rich Mayfield wrote:
> > However there doesn’t appear to be a way to force leadership to/from a
> > particular replica.
> I would have expected that doing a core reload on the current leader
> would force an election and move the leader, but on my 4.2.1 SolrCloud
> (the only version I have running at the moment) that does not appear to
> be happening.  IMHO we need a way to force a leader change on a shard.
> An API for "move all leaders currently on this Solr instance" would
> actually be a very useful feature.
> I can envision two issues for you to file in Jira.  The first would be
> an Improvement issue, the second would be a Bug:
> * SolrCloud: Add API to move leader off a Solr instance
> * SolrCloud: LotsOfCollections takes a long time to stabilize
> If we can get a dev who specializes in SolrCloud to respond, perhaps
> they'll have a recommendation about whether these are sensible issues,
> and if not, what they'd recommend.
> Thanks,
> Shawn

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