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From "Lin Yiqun (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HDFS-9756) Hard-Code value in DataTransferThrottler
Date Fri, 05 Feb 2016 02:14:39 GMT

     [ https://issues.apache.org/jira/browse/HDFS-9756?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Lin Yiqun updated HDFS-9756:
----------------------------
    Attachment: HDFS-9756.002.patch

Fix checkstyle errors and other errors, kindly review.

> Hard-Code value in DataTransferThrottler
> ----------------------------------------
>
>                 Key: HDFS-9756
>                 URL: https://issues.apache.org/jira/browse/HDFS-9756
>             Project: Hadoop HDFS
>          Issue Type: Bug
>    Affects Versions: 2.7.1
>            Reporter: Lin Yiqun
>            Assignee: Lin Yiqun
>         Attachments: HDFS-9756.001.patch, HDFS-9756.002.patch
>
>
> In DataTransferThrottler, the period time is hard-code for 500 ms. Even though it has
other construction method, 
> {code}
> /**
>    * Constructor
>    * @param period in milliseconds. Bandwidth is enforced over this
>    *        period.
>    * @param bandwidthPerSec bandwidth allowed in bytes per second. 
>    */
>   public DataTransferThrottler(long period, long bandwidthPerSec) {
>     this.curPeriodStart = monotonicNow();
>     this.period = period;
>     this.curReserve = this.bytesPerPeriod = bandwidthPerSec*period/1000;
>     this.periodExtension = period*3;
>   }
> {code}
> but it was only invoked by this method 
> {code}
> public DataTransferThrottler(long bandwidthPerSec) {
>     this(500, bandwidthPerSec);  // by default throttling period is 500ms 
> }
> {code}
> So the period is a hard-code. This value can also influence the data-transfering. If
period time value set small, the number of times to waitting for next period will be increased
and the total waitting-time also  be increased. So the average bandwidth will be decreased.



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