[jira] [Comment Edited] (SOLR-14274) Multiple CoreContainers will register the same JVM Metrics

["Mike Drob (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SOLR-14274?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17042129#comment-17042129 ] 

Mike Drob edited comment on SOLR-14274 at 2/21/20 7:54 PM:
-----------------------------------------------------------

The comment in {{SolrMetricManagerTest}}:
{code}
    // this should simply skip existing names
    metricManager.registerAll(registryName, mr, true);
{code}
confuses me regarding what the expected behavior really is.

And the java doc on {{registerAll}}:
{code}
   * Register all metrics in the provided {@link MetricSet}, optionally skipping those that
   * already exist.
{code}
But there doesn't appear to be a way to actually skip. Either replace or throw exception on conflict.


was (Author: mdrob):
The comment in {{SolrMetricManagerTest}}:
{code}
    // this should simply skip existing names
    metricManager.registerAll(registryName, mr, true);
{code}
confuses me regarding what the expected behavior really is.

> Multiple CoreContainers will register the same JVM Metrics
> ----------------------------------------------------------
>
>                 Key: SOLR-14274
>                 URL: https://issues.apache.org/jira/browse/SOLR-14274
>             Project: Solr
>          Issue Type: Bug
>      Security Level: Public(Default Security Level. Issues are Public) 
>            Reporter: Mike Drob
>            Priority: Major
>
> When running multiple CoreContainer in the same JVM, either because we called {{SolrCloudTestCase.configureCluster(int n)}} with {{n > 1}} or because we have multiple tests running in the same JVM in succession, we will have contention on the shared JVM {{metricsRegistry}} as they each replace the existing metrics with their own. Further, with multiple nodes at the same time, some of these metrics will be incorrect anyway, since they will only reflect a single core container. Others will be fine since I think they are reading system-level information so it doesn't matter where it comes from.
> I think this is a test-only issue, since the circumstances where somebody is running multiple core containers in a single JVM in production should be rare, but maybe there are edge cases affected with EmbeddedSolrServer and MapReduce or Spark, or other unusual deployment patterns.
> Removing the metrics registration entirely can speed up {{configureCluster(100).build()}} on my machine from 2 minutes to 30 seconds, so I'm optimistic that there can be gains here without sacrificing the feature entirely.



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