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https://issues.apache.org/jira/browse/HDFS-10175?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15254197#comment-15254197
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Ming Ma commented on HDFS-10175:
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This is a great idea. It also addresses an issue at the consumption side. MR
iterates through these counters in all FileSystems regardless they are
implemented or not, which will increase the number of MR Counters causing
unnecessary overhead at MR layer such as rpc, history file, webUI, etc.
As part of the patch evaluation, it might be useful to try this out with MR end
to end. Ideally MR doesn't need to change code each time a new method is added
to HDFS ClientProtocol. If so, MR File System Counter needs to be more dynamic;
maybe the more descriptive File System Counter string should come from
FileSystem, etc. It might help to flush out some of the details.
> add per-operation stats to FileSystem.Statistics
> ------------------------------------------------
>
> Key: HDFS-10175
> URL: https://issues.apache.org/jira/browse/HDFS-10175
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: hdfs-client
> Reporter: Ram Venkatesh
> Assignee: Mingliang Liu
> Attachments: 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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