Qpid
  1. Qpid
  2. QPID-2454

[Patch] Messages set with a TTL expire immediately when sent on qpid queues with LVQ ordering

    Details

    • Type: Bug Bug
    • Status: Closed
    • Priority: Major Major
    • Resolution: Fixed
    • Affects Version/s: 0.5, 0.6, 0.7
    • Fix Version/s: 0.8
    • Component/s: C++ Broker
    • Labels:
    • Environment:

      RHEL-5 or later

      Description

      Problem Description:

      MRG LVQ becomes unstable when msg TTLs are used and a message expires. Sometimes when messages expire, it seems to upset the LVQ mechanism. Eg. Once a message with key 'X' has expired, any subsequent messages sent to the LVQ with key 'X' are expired immediately, and never made available to client applications. Once an LVQ begins exhibiting this behaviour, This behaviour continues until the broker is restarted. At this point, another side effect is that the msgDepth and byteDepth properties on an LVQ do not always agree, i.e, when msgDepth is zero, byteDepth is not zero.

      How Reproducible:

      Always:

      Steps to Reproduce:

      • Create a queue with queue ordering as lvq or lvq-no-browse
      • Build and run attached producer for 1 minute
      • Stop the producer for a minute to allow messages to expire
      • Use qpid-tool to monitor the queue depth and wait for the message to be dequeued (usually takes about 10 minutes)
      • Once message has expired, restart the producer
      • Watch queue properties with qpid-tool

      Actual Results:

      The queue depth is always 0, but the byte depth is not. Occasionally, one will get the following error message from the producer:

      Unexpected exception: Attempted size underflow on dequeue

      Expected Results:

      The queue depth should not be 0 (at least till the time expired messages are purged). Also, when queue depth is 0, byte depth should be 0.

      Additional Information:

      The root cause seems to be that the lvq object in the Queue that holds mapping from key to messages (Queue::lvq) is not cleared when messages are expired (Queue::purgeExpired), which leads to incorrect accounting when the next message arrives in the queue with the same LVQ key as the message that expired.

        Activity

        Hide
        Gordon Sim added a comment -

        Clearly more tests are needed in this area, but no reason not to mark this bug fixed now change has been made.

        Show
        Gordon Sim added a comment - Clearly more tests are needed in this area, but no reason not to mark this bug fixed now change has been made.
        Hide
        Carl Trieloff added a comment -

        Committed revision 928003.

        Leaving it open as Gordon had mentioned an additional case he wanted to test out.

        Carl.

        Show
        Carl Trieloff added a comment - Committed revision 928003. Leaving it open as Gordon had mentioned an additional case he wanted to test out. Carl.
        Hide
        Carl Trieloff added a comment -


        I confirmed this issues is not present anywhere else in the Queue.

        Show
        Carl Trieloff added a comment - I confirmed this issues is not present anywhere else in the Queue.
        Hide
        Siddhesh Poyarekar added a comment -

        Attached patch clears the lvq messages from the Queue::lvq map when that message has expired.

        Show
        Siddhesh Poyarekar added a comment - Attached patch clears the lvq messages from the Queue::lvq map when that message has expired.

          People

          • Assignee:
            Carl Trieloff
            Reporter:
            Siddhesh Poyarekar
          • Votes:
            0 Vote for this issue
            Watchers:
            1 Start watching this issue

            Dates

            • Created:
              Updated:
              Resolved:

              Development