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https://issues.apache.org/jira/browse/HDFS-9579?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Ming Ma updated HDFS-9579:
--------------------------
    Attachment: HDFS-9579-branch-2.patch

Thank you [~sjlee0], [~liuml07] and [~cmccabe]! Here is the patch for branch-2 
which passed all tests under hadoop-common-project and hadoop-hdfs-project 
locally.

> 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
>             Fix For: 3.0.0
>
>         Attachments: HDFS-9579-10.patch, 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-branch-2.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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