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https://issues.apache.org/jira/browse/HDFS-13674?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16534752#comment-16534752
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Yiqun Lin commented on HDFS-13674:
----------------------------------
[~csun], thanks for updating the patch.
{noformat}
....if `rpc.metrics.quantile.enable` is set to true. *num* is specified by
`rpc.metrics.percentiles.intervals`. |
{noformat}
The config {{rpc.metrics.quantile.enable}} and
{{rpc.metrics.percentiles.intervals}} is making sense for Aggregate RPC metrics
in COMMON. For NameNode metrics you updated in patch, following description is
correct.
{noformat}
Percentile measurement is off by default, by watching no intervals. The
intervals are specified by `dfs.metrics.percentiles.intervals`. |
{noformat}
Related codes:
{code}
public static NameNodeMetrics create(Configuration conf, NamenodeRole r) {
String sessionId = conf.get(DFSConfigKeys.DFS_METRICS_SESSION_ID_KEY);
String processName = r.toString();
MetricsSystem ms = DefaultMetricsSystem.instance();
JvmMetrics jm = JvmMetrics.create(processName, sessionId, ms);
// Percentile measurement is off by default, by watching no intervals
int[] intervals =
conf.getInts(DFSConfigKeys.DFS_METRICS_PERCENTILES_INTERVALS_KEY);
return ms.register(new NameNodeMetrics(processName, sessionId,
intervals, jm));
}
{code}
> Improve documentation on Metrics
> --------------------------------
>
> Key: HDFS-13674
> URL: https://issues.apache.org/jira/browse/HDFS-13674
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: documentation, metrics
> Reporter: Chao Sun
> Assignee: Chao Sun
> Priority: Minor
> Attachments: HDFS-13674.000.patch, HDFS-13674.001.patch
>
>
> There are a few confusing places in the [Hadoop Metrics
> page|https://hadoop.apache.org/docs/stable/hadoop-project-dist/hadoop-common/Metrics.html].
> For instance, there are duplicated entries such as {{FsImageLoadTime}}; some
> quantile metrics do not have corresponding entries, description on some
> quantile metrics are not very specific on what is the {{num}} variable in the
> metrics name, etc.
> This JIRA targets at improving this.
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