[HADOOP-3398] ReduceTask::closestPowerOf2 is inefficient

• Type: Improvement
• Status: Closed
• Priority: Trivial
• Resolution: Fixed
• Fix Version/s: 0.18.0
• Hadoop Flags: Reviewed
• Assignee: Christopher Douglas
• Reporter: Christopher Douglas
• Created: 15/May/08 22:19
• Updated: 08/Jul/09 16:52
• Resolved: 19/May/08 21:20

Description

ReduceTask computes the "closest power of 2" using loops

private static int getClosestPowerOf2(int value) {
  int power = 0;
  int approx = 1;
  while (approx < value) {
    ++power;
    approx = (approx << 1);
  }
  if ((value - (approx >> 1)) < (approx - value)) {
    --power;
  }
  return power;
}

This could be improved.