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https://issues.apache.org/jira/browse/HDFS-14084?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16719331#comment-16719331
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Íñigo Goiri commented on HDFS-14084:
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Thanks [~pranay_singh] for adding the log capturer.
Minor comments:
* The import in {{Client}} is a dded in a weird place and removing a space. Can
you put it in the right order in {{org.apache.hadoop}}?
* For {{rpcDetailedMetrics}} can you put the protected first? Follow the common
order.
* Extra break line after {{Client#218}}.
* Add javadoc to {{Client#updateMetrics}} and {{Client#getRpcDetailedMetrics}}?
* Why is there a space in the debug message {{ RPC Client stats:}}? It should
be right away.
* Add a break line in {{RpcDetailedMetrics#83}}.
* In {{TestClientMetrics}}, can you extract the output and then actually check
for the number of operations? {{output.contains("MkdirsNumOps = 1")}}.
* In the {{assertTrue}}, we should print the output: assertTrue("Unexpected
output in: " + output, output.contains("MkdirsNumOps = 1"));
> Need for more stats in DFSClient
> --------------------------------
>
> Key: HDFS-14084
> URL: https://issues.apache.org/jira/browse/HDFS-14084
> Project: Hadoop HDFS
> Issue Type: Improvement
> Affects Versions: 3.0.0
> Reporter: Pranay Singh
> Assignee: Pranay Singh
> Priority: Minor
> Attachments: HDFS-14084.001.patch, HDFS-14084.002.patch,
> HDFS-14084.003.patch, HDFS-14084.004.patch, HDFS-14084.005.patch
>
>
> The usage of HDFS has changed from being used as a map-reduce filesystem, now
> it's becoming more of like a general purpose filesystem. In most of the cases
> there are issues with the Namenode so we have metrics to know the workload or
> stress on Namenode.
> However, there is a need to have more statistics collected for different
> operations/RPCs in DFSClient to know which RPC operations are taking longer
> time or to know what is the frequency of the operation.These statistics can
> be exposed to the users of DFS Client and they can periodically log or do
> some sort of flow control if the response is slow. This will also help to
> isolate HDFS issue in a mixed environment where on a node say we have Spark,
> HBase and Impala running together. We can check the throughput of different
> operation across client and isolate the problem caused because of noisy
> neighbor or network congestion or shared JVM.
> We have dealt with several problems from the field for which there is no
> conclusive evidence as to what caused the problem. If we had metrics or stats
> in DFSClient we would be better equipped to solve such complex problems.
> List of jiras for reference:
> -------------------------
> HADOOP-15538 HADOOP-15530 ( client side deadlock)
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