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https://issues.apache.org/jira/browse/YARN-1529?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13856023#comment-13856023
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Hitesh Shah commented on YARN-1529:
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[~jira.shegalov] Could you add more details on how users should interpret these
new metrics? Does the cache ratio account for the local resource visibility
i.e. public cache misses are more important than cache misses for application
visibility? I assume the "LocalizationDownloadNanos" is an average per
container? How does an average help when there are numerous application types
with diff no. of resources and each container facing a different cache hit
ratio? Is this something which needs to be augmented into the container status
and not a general NM metric? For that matter, what is the better option -
trackinglocalization metrics on the NM level or tracking them on a per
container/per app level?
Further thoughts:
- Shouldn't there be a metric that tracks the actual size of the local
resource cache on disk?
- How are public/private/application caches being considered?
- What about different resource types - file/archive/pattern?
> Add Localization overhead metrics to NM
> ---------------------------------------
>
> Key: YARN-1529
> URL: https://issues.apache.org/jira/browse/YARN-1529
> Project: Hadoop YARN
> Issue Type: Bug
> Components: nodemanager
> Reporter: Gera Shegalov
> Assignee: Gera Shegalov
> Attachments: YARN-1529.v01.patch
>
>
> Users are often unaware of localization cost that their jobs incur. To
> measure effectiveness of localization caches it is necessary to expose the
> overhead in the form of metrics.
> We propose addition of the following metrics to NodeManagerMetrics.
> When a container is about to launch, its set of LocalResources has to be
> fetched from a central location, typically on HDFS, that results in a number
> of download requests for the files missing in caches.
> LocalizedFilesMissed: total files (requests) downloaded from DFS. Cache
> misses.
> LocalizedFilesCached: total localization requests that were served from local
> caches. Cache hits.
> LocalizedBytesMissed: total bytes downloaded from DFS due to cache misses.
> LocalizedBytesCached: total bytes satisfied from local caches.
> Localized(Files|Bytes)CachedRatio: percentage of localized (files|bytes) that
> were served out of cache: ratio = 100 * caches / (caches + misses)
> LocalizationDownloadNanos: total elapsed time in nanoseconds for a container
> to go from ResourceRequestTransition to LocalizedTransition
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