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https://issues.apache.org/jira/browse/HADOOP-13065?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Mingliang Liu updated HADOOP-13065:
-----------------------------------
    Attachment: HADOOP-13065.010.patch

Thanks [~cmccabe] for the comment. The v10 patch deprecates the getStatistics() 
API, and fixes the simple checkstyle warning.

One quick question is that, some of the storage statistics classes (e.g. 
{{GlobalStorageStatistics}} are annotated as {{Stable}}, do we have to be a bit 
more conservative by making them {{Unstable}} before ultimately removing the 
Statistics?

As follow-on work,
# We can move the rack-awareness read bytes to a separate storage statistics as 
it's only used by HDFS
# We can remove Statistics API, but keep the thread local implementation in  
{{FileSystemStorageStatistics}} class.

I will update the previously filed jiras [HADOOP-13032] and [HADOOP-13031] 
accordingly after this patch is in the trunk.

> Add a new interface for retrieving FS and FC Statistics
> -------------------------------------------------------
>
>                 Key: HADOOP-13065
>                 URL: https://issues.apache.org/jira/browse/HADOOP-13065
>             Project: Hadoop Common
>          Issue Type: Improvement
>          Components: fs
>            Reporter: Ram Venkatesh
>            Assignee: Mingliang Liu
>         Attachments: HADOOP-13065-007.patch, HADOOP-13065.008.patch, 
> HADOOP-13065.009.patch, HADOOP-13065.010.patch, HDFS-10175.000.patch, 
> HDFS-10175.001.patch, HDFS-10175.002.patch, HDFS-10175.003.patch, 
> HDFS-10175.004.patch, HDFS-10175.005.patch, HDFS-10175.006.patch, 
> TestStatisticsOverhead.java
>
>
> Currently FileSystem.Statistics exposes the following statistics:
> BytesRead
> BytesWritten
> ReadOps
> LargeReadOps
> WriteOps
> These are in-turn exposed as job counters by MapReduce and other frameworks. 
> There is logic within DfsClient to map operations to these counters that can 
> be confusing, for instance, mkdirs counts as a writeOp.
> Proposed enhancement:
> Add a statistic for each DfsClient operation including create, append, 
> createSymlink, delete, exists, mkdirs, rename and expose them as new 
> properties on the Statistics object. The operation-specific counters can be 
> used for analyzing the load imposed by a particular job on HDFS. 
> For example, we can use them to identify jobs that end up creating a large 
> number of files.
> Once this information is available in the Statistics object, the app 
> frameworks like MapReduce can expose them as additional counters to be 
> aggregated and recorded as part of job summary.



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