[HDFS-3485] DataTransferThrottler will over-throttle when currentTimeMillis jumps

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.0.0-alpha
• Fix Version/s: 2.0.2-alpha
• Hadoop Flags: Reviewed
• Assignee: Andy Isaacson
• Reporter: Andy Isaacson
• Created: 31/May/12 18:41
• Updated: 11/Oct/12 17:46
• Resolved: 07/Jun/12 18:43

Description

When the system clock is set backwards, DataTransferThrottler will simply pause until the clock reaches the end of the previously calculated transfer period:

    this.curPeriodStart = System.currentTimeMillis();
...
    while (curReserve <= 0) {
      long now = System.currentTimeMillis();
      long curPeriodEnd = curPeriodStart + period;
      if ( now < curPeriodEnd ) {
        try {
          wait( curPeriodEnd - now );

Instead of using currentTimeMillis() which is affected by system-clock-changes, this code should use nanoTime which ticks forward monotonically.