[HDFS-9756] Hard-Code value in DataTransferThrottler

• Type: Bug
• Status: Patch Available
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 2.7.1
• Assignee: Yiqun Lin
• Reporter: Yiqun Lin
• Created: 04/Feb/16 15:30
• Updated: 25/Apr/19 08:00

Description

In DataTransferThrottler, the period time is hard-code for 500 ms. Even though it has other construction method,

/**
   * 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;
  }

but it was only invoked by this method

public DataTransferThrottler(long bandwidthPerSec) {
    this(500, bandwidthPerSec);  // by default throttling period is 500ms 
}

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.