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https://issues.apache.org/jira/browse/HDFS-9756?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16825834#comment-16825834
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bianqi commented on HDFS-9756:
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Why is there no one paying attention to this problem?
> 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: Yiqun Lin
> Assignee: Yiqun Lin
> Priority: Major
> 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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