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From "Mingliang Liu (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-9579) Provide bytes-read-by-network-distance metrics at FileSystem.Statistics level
Date Thu, 03 Mar 2016 23:50:18 GMT

    [ https://issues.apache.org/jira/browse/HDFS-9579?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15178871#comment-15178871
] 

Mingliang Liu commented on HDFS-9579:
-------------------------------------

+1 (non-binding) pending on Jenkins.

> Provide bytes-read-by-network-distance metrics at FileSystem.Statistics level
> -----------------------------------------------------------------------------
>
>                 Key: HDFS-9579
>                 URL: https://issues.apache.org/jira/browse/HDFS-9579
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>            Reporter: Ming Ma
>            Assignee: Ming Ma
>         Attachments: HDFS-9579-2.patch, HDFS-9579-3.patch, HDFS-9579-4.patch, HDFS-9579-5.patch,
HDFS-9579-6.patch, HDFS-9579-7.patch, HDFS-9579-8.patch, HDFS-9579-9.patch, HDFS-9579.patch,
MR job counters.png
>
>
> For cross DC distcp or other applications, it becomes useful to have insight as to the
traffic volume for each network distance to distinguish cross-DC traffic, local-DC-remote-rack,
etc.
> FileSystem's existing {{bytesRead}} metrics tracks all the bytes read. To provide additional
metrics for each network distance, we can add additional metrics to FileSystem level and have
{{DFSInputStream}} update the value based on the network distance between client and the datanode.
> {{DFSClient}} will resolve client machine's network location as part of its initialization.
It doesn't need to resolve datanode's network location for each read as {{DatanodeInfo}} already
has the info.
> There are existing HDFS specific metrics such as {{ReadStatistics}} and {{DFSHedgedReadMetrics}}.
But these metrics are only accessible via {{DFSClient}} or {{DFSInputStream}}. Not something
that application framework such as MR and Tez can get to. That is the benefit of storing these
new metrics in FileSystem.Statistics.
> This jira only includes metrics generation by HDFS. The consumption of these metrics
at MR and Tez will be tracked by separated jiras.
> We can add similar metrics for HDFS write scenario later if it is necessary.



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