[jira] [Created] (KAFKA-938) High CPU usage when more or less idle

["Sam Meder (JIRA)" <ji...@apache.org>]

Sam Meder created KAFKA-938:
-------------------------------

             Summary: High CPU usage when more or less idle
                 Key: KAFKA-938
                 URL: https://issues.apache.org/jira/browse/KAFKA-938
             Project: Kafka
          Issue Type: Bug
          Components: core
    Affects Versions: 0.8
            Reporter: Sam Meder
            Priority: Critical
             Fix For: 0.8


We've noticed Kafka using a lot of CPU in a pretty much idle environment and tracked it down to it's DelayedItem implementation. In particular, the time conversion for how much longer to wait:

  def getDelay(unit: TimeUnit): Long = {
    val elapsedMs = (SystemTime.milliseconds - createdMs)
    unit.convert(max(delayMs - elapsedMs, 0), unit)
  }

does not actually convert, so Kafka ends up treating a ms value like nanoseconds, e.g. waking up every 100 ns or so. The above code should really be:

  def getDelay(unit: TimeUnit): Long = {
    val elapsedMs = (SystemTime.milliseconds - createdMs)
    unit.convert(max(delayMs - elapsedMs, 0), TimeUnit.MILLISECONDS)
  }

I'll attach a patch.



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