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From "Erik Krogen (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-14084) Need for more stats in DFSClient
Date Thu, 06 Dec 2018 17:33:00 GMT

    [ https://issues.apache.org/jira/browse/HDFS-14084?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16711760#comment-16711760
] 

Erik Krogen commented on HDFS-14084:
------------------------------------

[~pranay_singh] - thanks for taking this on, this is really valuable work. Regarding:
{quote}
the problem with StorageStatistics is that it just records the frequency of a particular operation
and not it's latency
{quote}
Ideally this would be great time to _extend_ {{StorageStatistics}} to support latency as well
as frequency. This is work I am particularly interested in and was planning on tackling soon,
I would love to collaborate. {{StorageStatistics}} has had some great work done on it so far,
and it isn't quite where it needs to be yet, but the only way it will get there is by us continuing
to make it better. Going down a parallel path that doesn't have long-term and/or shareable
benefits isn't good in the long run.

> 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
>
>
> 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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