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Posted to dev@lucene.apache.org by "Noble Paul (JIRA)" <ji...@apache.org> on 2015/02/26 14:29:04 UTC
[jira] [Resolved] (SOLR-7129) CloudSolrClient can put extra load on
ZooKeeper for collections with stateFormat=2
[ https://issues.apache.org/jira/browse/SOLR-7129?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Noble Paul resolved SOLR-7129.
------------------------------
Resolution: Duplicate
> CloudSolrClient can put extra load on ZooKeeper for collections with stateFormat=2
> ----------------------------------------------------------------------------------
>
> Key: SOLR-7129
> URL: https://issues.apache.org/jira/browse/SOLR-7129
> Project: Solr
> Issue Type: Bug
> Components: SolrCloud, SolrJ
> Affects Versions: 5.0
> Reporter: Shalin Shekhar Mangar
> Assignee: Noble Paul
> Labels: difficulty-medium, impact-high
> Fix For: Trunk, 5.1
>
>
> Each stale state response from the server causes CloudSolrClient to evict the requested collection from the local cache. At this point, the request is retried and the latest collection state is fetched live from ZooKeeper. -There is nothing preventing multiple request threads to simultaneously hit ZooKeeper and cause a thundering herd effect.- There is synchronization to prevent multiple request threads from simultaneously trying to refresh the state but that is not enough. Each request thread which receives a stale state will sequentially refresh state from ZK after acquiring the lock.
> We should use the past and current znode version of the cluster state to make sure that redundant fetches from ZooKeeper are never possible.
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