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https://issues.apache.org/jira/browse/SOLR-5986?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14159212#comment-14159212
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Steve Davids commented on SOLR-5986:
------------------------------------

Why wouldn't it return partial results? When sending a distributed request if 
all but one return results but one shard lags behind at query expansion one 
would think that you would get the appropriate partial results message. Unless 
this is partially related to SOLR-6496 which would retry a different replica in 
the shard group and thus *could* cause a timeout at the Solr distributed 
aggregation layer.

> Don't allow runaway queries from harming Solr cluster health or search 
> performance
> ----------------------------------------------------------------------------------
>
>                 Key: SOLR-5986
>                 URL: https://issues.apache.org/jira/browse/SOLR-5986
>             Project: Solr
>          Issue Type: Improvement
>          Components: search
>            Reporter: Steve Davids
>            Assignee: Anshum Gupta
>            Priority: Critical
>             Fix For: 5.0
>
>         Attachments: SOLR-5986.patch, SOLR-5986.patch, SOLR-5986.patch, 
> SOLR-5986.patch, SOLR-5986.patch, SOLR-5986.patch, SOLR-5986.patch, 
> SOLR-5986.patch, SOLR-5986.patch, SOLR-5986.patch, SOLR-5986.patch, 
> SOLR-5986.patch
>
>
> The intent of this ticket is to have all distributed search requests stop 
> wasting CPU cycles on requests that have already timed out or are so 
> complicated that they won't be able to execute. We have come across a case 
> where a nasty wildcard query within a proximity clause was causing the 
> cluster to enumerate terms for hours even though the query timeout was set to 
> minutes. This caused a noticeable slowdown within the system which made us 
> restart the replicas that happened to service that one request, the worst 
> case scenario are users with a relatively low zk timeout value will have 
> nodes start dropping from the cluster due to long GC pauses.
> [~amccurry] Built a mechanism into Apache Blur to help with the issue in 
> BLUR-142 (see commit comment for code, though look at the latest code on the 
> trunk for newer bug fixes).
> Solr should be able to either prevent these problematic queries from running 
> by some heuristic (possibly estimated size of heap usage) or be able to 
> execute a thread interrupt on all query threads once the time threshold is 
> met. This issue mirrors what others have discussed on the mailing list: 
> http://mail-archives.apache.org/mod_mbox/lucene-solr-user/200903.mbox/%3c856ac15f0903272054q2dbdbd19kea3c5ba9e105b...@mail.gmail.com%3E



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