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https://issues.apache.org/jira/browse/SOLR-10130?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15870444#comment-15870444
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Erick Erickson commented on SOLR-10130:
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Ah, ok. I take it this is a replica with a bunch of data in it? Although this
doesn't make sense, there shouldn't be that much work do fire up a core absent
tlog replay and the like but it sounds like you're far beyond that so I'm
missing something.
Is there any way you could pull/build a new version of Solr 6.4 (or apply the
patch on this JIRA locally) and try? I'd hate to have the 6.4.2 release get out
(coming soon, due to this) and not have fixed a different issue.
> 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
> Assignee: Andrzej Bialecki
> Priority: Blocker
> Labels: perfomance
> Fix For: master (7.0), 6.4.2
>
> Attachments: SOLR-10130.patch, SOLR-10130.patch,
> 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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