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https://issues.apache.org/jira/browse/SOLR-10130?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15863948#comment-15863948
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Walter Underwood commented on SOLR-10130:
-----------------------------------------

I’m seeing similar problems here. With 6.4.0, we were handling 6000 
requests/minute. With 6.4.1 it is 1000 rpm with median response times around 
2.5 seconds. I also switched to the G1 collector. I’m going to back that out 
and retest today to see if the performance comes back.

Does disabling metrics fix it or we we need to go back to 6.4.0?

wunder

> Serious performance degradation in Solr 6.4.1 due to the new metrics 
> collection
> -------------------------------------------------------------------------------
>
>                 Key: SOLR-10130
>                 URL: https://issues.apache.org/jira/browse/SOLR-10130
>             Project: Solr
>          Issue Type: Bug
>      Security Level: Public(Default Security Level. Issues are Public) 
>          Components: metrics
>    Affects Versions: 6.4.1
>         Environment: Centos 7, OpenJDK 1.8.0 update 111
>            Reporter: Ere Maijala
>            Priority: Blocker
>              Labels: perfomance
>         Attachments: solr-8983-console-f1.log
>
>
> We've stumbled on serious performance issues after upgrading to Solr 6.4.1. 
> Looks like the new metrics collection system in MetricsDirectoryFactory is 
> causing a major slowdown. This happens with an index configuration that, as 
> far as I can see, has no metrics specific configuration and uses 
> luceneMatchVersion 5.5.0. In practice a moderate load will completely bog 
> down the server with Solr threads constantly using up all CPU (600% on 6 core 
> machine) capacity with a load that normally  where we normally see an average 
> load of < 50%.
> I took stack traces (I'll attach them) and noticed that the threads are 
> spending time in com.codahale.metrics.Meter.mark. I tested building Solr 
> 6.4.1 with the metrics collection disabled in MetricsDirectoryFactory getByte 
> and getBytes methods and was unable to reproduce the issue.
> As far as I can see there are several issues:
> 1. Collecting metrics on every single byte read is slow.
> 2. Having it enabled by default is not a good idea.
> 3. The comment "enable coarse-grained metrics by default" at 
> https://github.com/apache/lucene-solr/blob/branch_6x/solr/core/src/java/org/apache/solr/update/SolrIndexConfig.java#L104
>  implies that only coarse-grained metrics should be enabled by default, and 
> this contradicts with collecting metrics on every single byte read.



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