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https://issues.apache.org/jira/browse/SOLR-17106?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ASF GitHub Bot updated SOLR-17106:
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    Labels: pull-request-available  (was: )

> LBSolrClient: Make it configurable to remove zombie ping checks
> ---------------------------------------------------------------
>
>                 Key: SOLR-17106
>                 URL: https://issues.apache.org/jira/browse/SOLR-17106
>             Project: Solr
>          Issue Type: Improvement
>            Reporter: Aparna Suresh
>            Priority: Minor
>              Labels: pull-request-available
>          Time Spent: 1h
>  Remaining Estimate: 0h
>
> Following discussion from a dev list discussion here: 
> [https://lists.apache.org/thread/f0zfmpg0t48xrtppyfsmfc5ltzsq2qqh]
> The issue involves scalability challenges in SolrJ's *LBSolrClient* when a 
> pod with numerous cores experiences connectivity problems. The "zombie" 
> tracking mechanism, operating on a core basis, becomes a bottleneck during 
> distributed search on a massive multi shard collection. Threads attempting to 
> reach unhealthy cores contribute to a high computational load, causing 
> performance issues. 
> As suggested by Chris Hostetter: LBSolrClient could be configured to disable 
> zombie "ping" checks, but retain zombie tracking. Once a replica/endpoint is 
> identified as a zombie, it could be held in zombie jail for X seconds, before 
> being released - hoping that by this timeframe ZK would be updated to mark 
> this endpoint DOWN or the pod is back up and CloudSolrClient would avoid 
> querying it. In any event, only 1 failed query would be needed to send the 
> server back to zombie jail.
>  
> There are benefits in doing this change:
>  * Eliminate the zombie ping requests, which would otherwise overload pod(s) 
> coming up after a restart
>  * Avoid memory leaks, in case a node/replica goes away permanently, but it 
> stays as zombie forever, with a background thread in LBSolrClient constantly 
> pinging it



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