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https://issues.apache.org/jira/browse/SOLR-8785?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15684725#comment-15684725
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Jeff Wartes commented on SOLR-8785:
-----------------------------------
Understood, I'm all for incremental change, and I don't see "how to make a
Reporter" as part of this issue. I will be slightly disappointed though, if we
convert to the library without also providing a recommended access path for the
use of that library. Gathering metrics you can't report on is useless, and one
of the things I liked about the original patch was this:
{code}
if(this.pluginInfo==null) {
// if a request handler has a name, use a persistent, reportable timer
under that name
if (pluginInfo.name != null)
requestTimes = Metrics.namedTimer(Metrics.mkName(this.getClass(),
pluginInfo.name), REGISTRY_NAME);
this.pluginInfo = pluginInfo;
}
{code}
This meant that I automatically got access to all the relevant metrics for any
named request handler, using any Reporters (Log, JMX, Graphite, whatever) I
cared to attach. This, in turn, was only possible because all those metrics
were in a well-defined and accessible location.
> Use Metrics library for core metrics
> ------------------------------------
>
> Key: SOLR-8785
> URL: https://issues.apache.org/jira/browse/SOLR-8785
> Project: Solr
> Issue Type: Improvement
> Affects Versions: 4.1
> Reporter: Jeff Wartes
> Labels: patch, patch-available
> Attachments: SOLR-8785-increment.patch, SOLR-8785.patch,
> SOLR-8785.patch
>
>
> The Metrics library (https://dropwizard.github.io/metrics/3.1.0/) is a
> well-known way to track metrics about applications.
> In SOLR-1972, latency percentile tracking was added. The comment list is
> long, so here’s my synopsis:
> 1. An attempt was made to use the Metrics library
> 2. That attempt failed due to a memory leak in Metrics v2.1.1
> 3. Large parts of Metrics were then copied wholesale into the
> org.apache.solr.util.stats package space and that was used instead.
> Copy/pasting Metrics code into Solr may have been the correct solution at the
> time, but I submit that it isn’t correct any more.
> The leak in Metrics was fixed even before SOLR-1972 was released, and by
> copy/pasting a subset of the functionality, we miss access to other important
> things that the Metrics library provides, particularly the concept of a
> Reporter. (https://dropwizard.github.io/metrics/3.1.0/manual/core/#reporters)
> Further, Metrics v3.0.2 is already packaged with Solr anyway, because it’s
> used in two contrib modules. (map-reduce and morphines-core)
> I’m proposing that:
> 1. Metrics as bundled with Solr be upgraded to the current v3.1.2
> 2. Most of the org.apache.solr.util.stats package space be deleted outright,
> or gutted and replaced with simple calls to Metrics. Due to the copy/paste
> origin, the concepts should mostly map 1:1.
> I’d further recommend a usage pattern like:
> SharedMetricRegistries.getOrCreate(System.getProperty(“solr.metrics.registry”,
> “solr-registry”))
> There are all kinds of areas in Solr that could benefit from metrics tracking
> and reporting. This pattern allows diverse areas of code to track metrics
> within a single, named registry. This well-known-name then becomes a handle
> you can use to easily attach a Reporter and ship all of those metrics off-box.
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