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From "Jungtaek Lim (JIRA)" <>
Subject [jira] [Commented] (AMBARI-16946) Storm Metrics Sink has high chance to discard some datapoints
Date Mon, 30 May 2016 02:08:12 GMT


Jungtaek Lim commented on AMBARI-16946:

Since it's not an issue for specific version I left this blank for now.
Please guide how to label affects version/s if this issue is valid on 2.0.0 and above.

> Storm Metrics Sink has high chance to discard some datapoints
> -------------------------------------------------------------
>                 Key: AMBARI-16946
>                 URL:
>             Project: Ambari
>          Issue Type: Bug
>          Components: ambari-metrics
>            Reporter: Jungtaek Lim
>         Attachments: AMBARI-16946.patch
> There's a mismatch between TimelineMetricsCache and Storm metrics unit, while TimelineMetricsCache
considers "metric name + timestamp" to be unique but Storm is not.
> For example, assume that bolt B has task T1, T2 and B has registered metrics M1. It's
possible for metrics sink to receive (T1, M1) and (T2, M1) with same timestamp TS1 (in TaskInfo,
not current time), and received later will be discarded from TimelineMetricsCache.
> If we want to have unique metric point of Storm, we should use "topology name + component
name + task id + metric name" to metric name so that "metric name + timestamp" will be unique.
> There're other issues I would like to address, too.
> - Currently, hostname is written to hostname of the machine which runs metrics sink.
Since TaskInfo has hostname of the machine which runs task, we're better to use this.
> - Unit of timestamp of TaskInfo is second, while Storm Metrics Sink uses this as millisecond,
resulting in timestamp flaw, and malfunction of cache eviction. It should be multiplied by
> - 'component name' is not unique across the cluster, so it's not fit for app id. 'topology
name' is unique so proper value of app id is topology name. 

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