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https://issues.apache.org/jira/browse/SOLR-17656?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17933573#comment-17933573
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Chris M. Hostetter commented on SOLR-17656:
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[~houston] - i appreciate your help w/the test – but after reading your change
a couple of times now, and looking at the old version vs the new version, and
re-running w/your exact seed (and confirming that
{{testSkipLeaderRecoveryProperty}} ran before {{testRealTimeGet}}) I still
can't for the life of me understand when/why that failures would have happened
(in a way that your commit would now reliably prevent it from happening)
If the issue is that one of the jetties never restarted (or restarted too
slowly), then...
* I'd expect {{testSkipLeaderRecoveryProperty}} should have failed as well? ..
and if it didn't we shoudl also harden it's assertions
** but even then, i'd expect {{testRealTimeGet}} to timeout or fail when
creating it's collection -- not when adding a doc to that collection
* But also: {{testSkipLeaderRecoveryProperty}} isn't the first test in this
class to stop/restart jetty instances -- so if that's the problem it seems like
it could happen in other test methods as well, and the better fix would be to
put your "wait for live nodes" logic in a before/after method
...can you help walk me through what exactly the problem was and how your patch
fixed it?
> Add expert level option to allowe PULL replicas to go ACTIVE w/o RECOVERING
> ---------------------------------------------------------------------------
>
> Key: SOLR-17656
> URL: https://issues.apache.org/jira/browse/SOLR-17656
> Project: Solr
> Issue Type: New Feature
> Reporter: Chris M. Hostetter
> Assignee: Chris M. Hostetter
> Priority: Major
> Fix For: main (10.0), 9.9
>
> Attachments: SOLR-17656-1.patch, SOLR-17656.patch
>
>
> In situations where a Solr cluster undergoes a rolling restart (or some other
> "catastrophic" failure situations requiring/causing solr node restarts) there
> can be a snowball effect of poor performance (or even solr node crashing) due
> to fewer then normal replicas serving query requests while replicas on
> restarting nodes are DOWN or RECOVERING – especially if shard leaders are
> also affected, and (restarting) replicas first must wait for a leader
> election before they can recover (or wait to finish recovery from an
> over-worked leader).
> For NRT type usecases, RECOVERING is really a necessary evil to ensure every
> replicas is up to date before handling NRT requests – but in the case of PULL
> replicas, which are expected to routinely "lag" behind their leader, I've
> talked to a lot of Solr users w/usecases where they would be happy to have
> PULL replicas back online serving "stale" data ASAP, and let normal
> IndexFetching "catchup" with the leader later.
> I propose we support a new "advanced" replica property that can be set on
> PULL replicas by expert level users, to indicate: on (re)init, these replicas
> may skip RECOVERING and go directly to ACTIVE.
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