[jira] [Resolved] (HBASE-29399) Update hadoop-metrics2-hbase.properties template

["Junegunn Choi (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HBASE-29399?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Junegunn Choi resolved HBASE-29399.
-----------------------------------
    Fix Version/s: 2.7.0
                   3.0.0-beta-2
                   2.6.3
                   2.5.12
       Resolution: Fixed

Pushed to the following branches:
  * master
  * branch-3
  * branch-2
  * branch-2.5
  * branch-2.6

Thanks to [~zhangduo] for the review.

> Update hadoop-metrics2-hbase.properties template
> ------------------------------------------------
>
>                 Key: HBASE-29399
>                 URL: https://issues.apache.org/jira/browse/HBASE-29399
>             Project: HBase
>          Issue Type: Improvement
>          Components: conf, documentation
>            Reporter: Junegunn Choi
>            Assignee: Junegunn Choi
>            Priority: Major
>             Fix For: 2.7.0, 3.0.0-beta-2, 2.6.3, 2.5.12
>
>
> h2. Problem
> The [hadoop-metrics2-hbase.properties|https://github.com/apache/hbase/blob/master/conf/hadoop-metrics2-hbase.properties] configuration template has a few errors, and it doesn't provide enough examples to show how to configure the metrics.
> h2. Issues and suggestions
> h3. Invalid wildcard pattern
> {code}
> *.sink.file*.class=org.apache.hadoop.metrics2.sink.FileSink
> {code}
> It seems the original intention of {{file\*}} was to match all instances with {{file}} prefix. However, it doesn't work as expected. Such partial wildcard patterns are not allowed by [the regular expression|https://github.com/apache/hadoop/blob/8378ab9f92c72dc6164b62f7be71826fd750dba4/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/metrics2/impl/MetricsConfig.java#L88] in the Hadoop codebase.
> If we change it to {{\*.sink.\*.class}}, then it does match all instances. But that would be overly broad and likely unintended, so I don't think we should do that. Instead, I suggest just removing this line because it's pointless and misleading. We're already repeating {{org.apache.hadoop.metrics2.sink.FileSink}} on every sink anyway.
> h3. Incorrect context
> {code}
> # hbase.sink.file0.context=hmaster
> {code}
> The context should be {{master}}, not {{hmaster}}.
> h3. Incorrect filename
> {code}
> # hbase.sink.file1.class=org.apache.hadoop.metrics2.sink.FileSink
> # hbase.sink.file1.context=thrift-one
> # hbase.sink.file1.filename=thrift-one.metrics
> # hbase.sink.file2.class=org.apache.hadoop.metrics2.sink.FileSink
> # hbase.sink.file2.context=thrift-two
> # hbase.sink.file2.filename=thrift-one.metrics
> {code}
> You see the problem?
> h3. Missing regionserver context example
> I think it's strange that we don't show a sink example for {{regionserver}}, when we have others like thrift1, thrift2, and rest.
> h3. Better naming of instances
> The instances are named {{file-all}}, then {{file0}}, {{file1}}, {{file2}}, and so on. More descriptive names like {{file-master}} or {{file-thrift1}} would make the configuration easier to understand and maintain.
> h3. Provide a filtering example
> HBase emits a large number of metrics, and it is sometimes desired to reduce the number by filtering out the metrics you are not interested in. But the template doesn't provide a good example of how to do it.
> Here is a sample configuration (we actually use) that demonstrates how to exclude some metrics.
> {code}
> hbase.source.metric.filter.class=org.apache.hadoop.metrics2.filter.RegexFilter
> hbase.source.metric.filter.exclude=.*_((25|75|90|95|98)th_percentile|min|mean)
> {code}



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