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https://issues.apache.org/jira/browse/SOLR-11730?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16316378#comment-16316378
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ASF subversion and git services commented on SOLR-11730:
--------------------------------------------------------

Commit a9fec9bf7caee2620d09086efde4a29b245aab7b in lucene-solr's branch 
refs/heads/master from [~ab]
[ https://git-wip-us.apache.org/repos/asf?p=lucene-solr.git;h=a9fec9b ]

SOLR-11730: Collect more stats in the benchmark. Add simulation framework 
package docs.


> Test NodeLost / NodeAdded dynamics
> ----------------------------------
>
>                 Key: SOLR-11730
>                 URL: https://issues.apache.org/jira/browse/SOLR-11730
>             Project: Solr
>          Issue Type: Sub-task
>      Security Level: Public(Default Security Level. Issues are Public) 
>          Components: AutoScaling
>            Reporter: Andrzej Bialecki 
>
> Let's consider a "flaky node" scenario.
> A node is going up and down at short intervals (eg. due to a flaky network 
> cable). If the frequency of these events coincides with {{waitFor}} interval 
> in {{nodeLost}} trigger configuration, the node may never be reported to the 
> autoscaling framework as lost. Similarly it may never be reported as added 
> back if it's lost again within the {{waitFor}} period of {{nodeAdded}} 
> trigger.
> Other scenarios are possible here too, depending on timing:
> * node being constantly reported as lost
> * node being constantly reported as added
> One possible solution for the autoscaling triggers is that the framework 
> should keep a short-term ({{waitFor * 2}} long?) memory of a node state that 
> the trigger is tracking in order to eliminate flaky nodes (ie. those that 
> transitioned between states more than once within the period).
> Situation like this is detrimental to SolrCloud behavior regardless of 
> autoscaling actions, so it should probably be addressed at a node level by 
> eg. shutting down Solr node after the number of disconnects in a time window 
> reaches a certain threshold.



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