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https://issues.apache.org/jira/browse/HADOOP-13065?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15289689#comment-15289689
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Ming Ma commented on HADOOP-13065:
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[~liuml07] [~cmccabe], yeah the perf could be an issue. Regarding moving it to
ReadStatistics, the problem is there is no easy way for MR framework to get
hold of the HDFS streams used by the application.
> 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
> Fix For: 2.8.0
>
> Attachments: HADOOP-13065-007.patch, HADOOP-13065.008.patch,
> HADOOP-13065.009.patch, HADOOP-13065.010.patch, HADOOP-13065.011.patch,
> HADOOP-13065.012.patch, HADOOP-13065.013.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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