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https://issues.apache.org/jira/browse/SOLR-12386?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17089813#comment-17089813
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David Smiley commented on SOLR-12386:
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I think I know what the problem is: We're not taking care to ensure the reader
of a configSet (SolrCore load / ZkSolrResourceLoader) is seeing the most up to
date information from ZK on this configSet.
Public service reminder: ZooKeeper can appear to be eventually consistent
between clients (e.g. between Solr nodes). Thus clientA writes data then
clientB doesn't necessarily see it yet. One mechanism ZK has to help is a
"sync" call which can be used preceding a read when you need to guarantee
seeing the most recent information:
https://github.com/apache/zookeeper/blob/master/zookeeper-docs/src/main/resources/markdown/zookeeperProgrammers.md#ch_zkGuarantees
(see call-out note at the end of this section)
[~dragonsinth] I'd like your input on this, since you have more experience with
Curator / ZK than I do. A simple (naive?) solution is to add a ZK sync call in
the constructor of ZkSolrResourceLoader. However, might that potentially be
expensive, delaying the load of all SolrCores? Might there be a better way?
> Test fails for "Can't find resource" for files in the _default configset
> ------------------------------------------------------------------------
>
> Key: SOLR-12386
> URL: https://issues.apache.org/jira/browse/SOLR-12386
> Project: Solr
> Issue Type: Test
> Components: SolrCloud
> Reporter: David Smiley
> Priority: Minor
> Attachments: cant find resource, stacktrace.txt
>
>
> Some tests, especially ConcurrentCreateRoutedAliasTest, have failed
> sporadically failed with the message "Can't find resource" pertaining to a
> file that is in the default ConfigSet yet mysteriously can't be found. This
> happens when a collection is being created that ultimately fails for this
> reason.
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