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From "Mingliang Liu (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-9521) TransferFsImage.receiveFile should account and log separate times for image download and fsync to disk
Date Mon, 14 Dec 2015 19:37:46 GMT

    [ https://issues.apache.org/jira/browse/HDFS-9521?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15056559#comment-15056559
] 

Mingliang Liu commented on HDFS-9521:
-------------------------------------

The overhead should be fine. Overall information may be useful so that the operator does not
have to calculate from verbose information.

> TransferFsImage.receiveFile should account and log separate times for image download
and fsync to disk 
> -------------------------------------------------------------------------------------------------------
>
>                 Key: HDFS-9521
>                 URL: https://issues.apache.org/jira/browse/HDFS-9521
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>            Reporter: Wellington Chevreuil
>            Assignee: Wellington Chevreuil
>            Priority: Minor
>         Attachments: HDFS-9521.patch
>
>
> Currently, TransferFsImage.receiveFile is logging total transfer time as below:
> {noformat}
> double xferSec = Math.max(
>        ((float)(Time.monotonicNow() - startTime)) / 1000.0, 0.001);    
> long xferKb = received / 1024;
> LOG.info(String.format("Transfer took %.2fs at %.2f KB/s",xferSec, xferKb / xferSec))
> {noformat}
> This is really useful, but it just measures the total method execution time, which includes
time taken to download the image and do an fsync to all the namenode metadata directories.
> Sometime when troubleshooting these imager transfer problems, it's interesting to know
which part of the process is being the bottleneck (whether network or disk write).
> This patch accounts time for image download and fsync to each disk separately, logging
how much time did it take on each operation.
>  



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