qpid broker allows consuming messages from browse-only queue when transactions are used

Solution Verified - Updated -

Environment

  • Red Hat Enterprise MRG Messaging 2.3 and 2.3.3

Issue

  • browse-only queue used (where any consumer do not cause message removal from the queue, in fact any consumer is just a browser)
  • a consumer using transactions fetches messages from the queue
  • the messages from the queue are really consumed / dequeued

Resolution

  • The underlying bug is tracked in this Red Hat bugzilla and its fix is available in this errata.

Root Cause

  • The underlying bug allowed - when committing a transaction - that any message from the transaction to be dequeued, regardless of its acquired/ended state.

  • Apart from this impact, the bug causes qpid broker segfault when attempting to twice commit the same message acquire - see this solution for details.

Diagnostic Steps

  • Reproduction steps:
qpid-send -a "q; {create:always, node:{type:queue, durable:false, x-declare:{arguments:{qpid.browse-only:1}}}}" -m 4
echo "queue depth (should be 4): $(qpid-stat -q q | grep queue-depth | awk '{ print $2 }')"
qpid-receive -a q --tx 2 -m 4 --print-content=no
echo "queue depth (should be 4): $(qpid-stat -q q | grep queue-depth | awk '{ print $2 }')"

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