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https://issues.apache.org/jira/browse/SOLR-11478?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16205397#comment-16205397
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Cao Manh Dat commented on SOLR-11478:
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For shutdown case, this change makes sense and can easily get done. But for
startup cases, this is not trivial and bring little benefit
- When the node startup, it will register all its replicas as DOWN, therefore
we do not forward any requests to replicas which have state = DOWN, although
/live_nodes entry is already created.
- Replicas will want to receive updates requests when its state = RECOVERING (
but refuse query requests ) on startup, therefore live_nodes entry must already
be created.
So advice for anyone is looking at both /live_nodes and state of replica before
sending commands to them.
> Solr should remove it's entry from live_nodes in zk immediately on shutdown
> and add after solr has loaded it's cores and is ready to serve requests.
> ----------------------------------------------------------------------------------------------------------------------------------------------------
>
> Key: SOLR-11478
> URL: https://issues.apache.org/jira/browse/SOLR-11478
> Project: Solr
> Issue Type: Improvement
> Security Level: Public(Default Security Level. Issues are Public)
> Components: SolrCloud
> Reporter: Binoy Dalal
> Priority: Minor
>
> Solr currently, upon receiving the stop command, removes its entry from the
> zk /live_nodes znode after it has finished processing all inflight requests,
> just before finally shutting down.
> In this case, any applications that depend on a solr node's live_node entry
> to decide whether or not to query it fail once the stop command has been
> executed but solr has not yet fully shut down.
> Something similar occurs during startup of a solr node. The solr node seems
> to add it's entry to the /live_nodes in zk once it is up but before it has
> started accepting requests and once again, this causes dependent applications
> to fail in a similar fashion.
> Hence, removal of the node entry and addition of the same to the zk
> live_nodes immediately upon shutting down and at the very end upon coming up
> respectively will greatly benefit applications that depend the live_nodes
> znode.
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