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https://issues.apache.org/jira/browse/SOLR-10726?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18132072#comment-18132072
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Nick Shanin commented on SOLR-10726:
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>From code reading against apache/main b73f03976fa, after a replication in
>SolrCloud the replica closes and reopens its searcher
>(solr/core/src/java/org/apache/solr/handler/IndexFetcher.java:679, 807).
>firstSearcher listeners fire whenever no searcher is registered
>(solr/core/src/java/org/apache/solr/core/SolrCore.java:2640-2645), so they can
>run more than once per replica. Is that still the behaviour you see?
🤖 AI-generated 🤖
> SolrCloud opens multiple searchers on replica creation/startup
> --------------------------------------------------------------
>
> Key: SOLR-10726
> URL: https://issues.apache.org/jira/browse/SOLR-10726
> Project: Solr
> Issue Type: Bug
> Components: search, SolrCloud
> Affects Versions: 6.5.1
> Reporter: Shalin Shekhar Mangar
> Priority: Major
> Labels: difficulty-medium, impact-high
> Attachments: SOLR-10726.semaphore.newsearcher.test.patch,
> semaphore.newsearcher.test.log.txt
>
>
> I was investigating some curious behavior reported by a customer around first
> searcher event listeners and multiple searchers being opened when adding a
> new replica.
> Turns out that if you add a new replica to solrcloud:
> 1) Searchers are opened at least twice and possibly a third time
> 2) the first time is because of a new core coming online and opening searcher
> on an empty index -- only firstSearcher event listeners are fired here
> 3) second time is after replication is complete and we have new index files
> available -- firstSearcher event listeners are fired again because the old
> searcher opened on core load has already been closed and disposed so this is
> technically again a first searcher
> 4) third time happens after documents buffered during recovery are replayed
> -- if there was no indexing happening on leader then this step is skipped --
> a newSearcher event is fired here because we had already opened a searcher in
> the last step
> Now if instead of a new replica, a solr node is restarted then there can be
> upto four searcher opens -- the additional open is because of log replay on
> startup.
> So Solr spends a lot of time on unnecessary warming/autowarming on searchers
> that are discarded. It is not just warming because sometimes plugins such as
> SpellCheckComponent and SuggestComponent can also tie in to these listener
> events.
> We can probably cut a few of them or at least defer the decision of whether
> to fire these listeners to places such as RecoveryStrategy which have a
> better idea of whether it is worth it.
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