Uploaded image for project: 'Kafka'
  1. Kafka
  2. KAFKA-1441

Purgatory purge causes latency spikes

    Details

    • Type: Bug
    • Status: Resolved
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: None
    • Component/s: None
    • Labels:
      None

      Description

      The request purgatory has a funky thing where it periodically loops over all watches and purges them. If you have a fair number of partitions you can accumulate lots of watches and purging them can take a long time. During this time all expiry is halted.

      Here is an example log:
      [2014-05-08 21:07:41,950] INFO ExpiredRequestReaper-2 Expired request after 10ms: 5829 (kafka.server.RequestPurgatory$ExpiredRequestReaper)
      [2014-05-08 21:07:41,952] INFO ExpiredRequestReaper-2 Expired request after 10ms: 5882 (kafka.server.RequestPurgatory$ExpiredRequestReaper)
      [2014-05-08 21:07:41,967] INFO ExpiredRequestReaper-2 Expired request after 11ms: 5884 (kafka.server.RequestPurgatory$ExpiredRequestReaper)
      [2014-05-08 21:07:41,968] INFO ExpiredRequestReaper-2 Purging purgatory (kafka.server.RequestPurgatory$ExpiredRequestReaper)
      [2014-05-08 21:07:41,969] INFO ExpiredRequestReaper-2 Purged 0 requests from delay queue. (kafka.server.RequestPurgatory$ExpiredRequestReaper)
      [2014-05-08 21:07:42,305] INFO ExpiredRequestReaper-2 Purged 340809 (watcher) requests. (kafka.server.RequestPurgatory$ExpiredRequestReaper)
      [2014-05-08 21:07:42,305] INFO ExpiredRequestReaper-2 Expired request after 106ms: 5847 (kafka.server.RequestPurgatory$ExpiredRequestReaper)
      [2014-05-08 21:07:42,305] INFO ExpiredRequestReaper-2 Expired request after 106ms: 5904 (kafka.server.RequestPurgatory$ExpiredRequestReaper)
      [2014-05-08 21:07:42,328] INFO ExpiredRequestReaper-2 Expired request after 10ms: 5908 (kafka.server.RequestPurgatory$ExpiredRequestReaper)
      [2014-05-08 21:07:42,329] INFO ExpiredRequestReaper-2 Expired request after 10ms: 5852 (kafka.server.RequestPurgatory$ExpiredRequestReaper)
      [2014-05-08 21:07:42,343] INFO ExpiredRequestReaper-2 Expired request after 11ms: 5854 (kafka.server.RequestPurgatory$ExpiredRequestReaper)

      Combined with our buggy purgatory request impls that can sometimes hit their expiration this can lead to huge latency spikes.

        Attachments

          Issue Links

            Activity

              People

              • Assignee:
                Unassigned
                Reporter:
                jkreps Jay Kreps
              • Votes:
                0 Vote for this issue
                Watchers:
                1 Start watching this issue

                Dates

                • Created:
                  Updated:
                  Resolved: