8.2.2. Queue Threshold Alerts

Queue Threshold Alerts are issued by the broker when a queue with a capacity limit set (either qpid.max_size or qpid.max_count) approaches 80% of its limit. The figure of 80% is configurable across the server using the broker option --default-event-threshold-ratio. If you set this to zero, alerts are disabled for all queues by default. Additionally, you can override the default alert threshold per-queue using qpid.alert_count and qpid.alert_size when creating the queue.
The Alerts are sent via the QMF framework. You can subscribe to the alert messages by listening to the address qmf.default.topic/agent.ind.event.org_apache_qpid_broker.queueThresholdExceeded.#. Alerts are sent as map messages.
The following code demonstrates subscribing to and consuming alert messages:
Python
conn = Connection.establish("localhost:5672")
session = conn.session()
rcv = session.receiver("qmf.default.topic/agent.ind.event.org_apache_qpid_broker.queueThresholdExceeded.#")
while True:
  event = rcv.fetch()
  print "Threshold exceeded on queue %s" % event.content[0]["_values"]["qName"]
  print "     at a depth of %s messages, %s bytes" % (event.content[0]["_values"]["msgDepth"], event.content[0]["_values"]["byteDepth"])
  session.acknowledge()
Alert Repeat Gap

To avoid alert message flooding, there is a 60 second gap between alert messages. This can be overridden on a per-queue basis using the qpid.alert_repeat_gap to specify a different value in seconds.

Backwards-compatible aliases

The following aliases are maintained for compatibility with earlier clients:

  • x-qpid-maximum-message-count is equivalent to qpid.alert_count
  • x-qpid-maximum-message-size is equivalent to qpid.alert_size
  • x-qpid-minimum-alert-repeat-gap is equivalent to qpid.alert_repeat_gap
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