Hi All,

We have been validating the new Qpid broker (version 6.0.4) and have
compared against broker version 0.32 and are seeing major regressions.
Following is the summary of our test setup and results:

*1. Test Setup *
  *a). *Qpid broker runs on a dedicated host (12 cores, 32 GB RAM).
  *b).* For 0.32, we allocated 16 GB heap. For 6.0.6 broker, we use 8GB
heap and 8GB direct memory.
  *c).* For 6.0.4, flow to disk has been configured at 60%.
  *d).* Both the brokers use BDB host type.
  *e).* Brokers have around 6000 queues and we create 16 listener
sessions/threads spread over 3 connections, where each session is listening
to 3000 queues. However, messages are only enqueued and processed from 10
  *f).* We enqueue 1 million messages across 10 different queues (evenly
divided), at the start of the test. Dequeue only starts once all the
messages have been enqueued. We run the test for 2 hours and process as
many messages as we can. Each message runs for around 200 milliseconds.
  *g).* We have used both 0.16 and 6.0.4 clients for these tests (6.0.4
client only with 6.0.4 broker)

*2. Test Results *
  *a).* System Load Average (read notes below on how we compute it), for
6.0.4 broker is 5x compared to 0.32 broker. During start of the test (when
we are not doing any dequeue), load average is normal (0.05 for 0.32 broker
and 0.1 for new broker), however, while we are dequeuing messages, the load
average is very high (around 0.5 consistently).

  *b). *Time to create listeners in new broker has gone up by 220% compared
to 0.32 broker (when using 0.16 client). For old broker, creating 16
sessions each listening to 3000 queues takes 142 seconds and in new broker
it took 456 seconds. If we use 6.0.4 client, it took even longer at 524%
increase (887 seconds).
     *I).* The time to create consumers increases as we create more
listeners on the same connections. We have 20 sessions (but end up using
around 5 of them) on each connection and we create about 3000 consumers and
attach MessageListener to it. Each successive session takes longer
(approximately linear increase) to setup same number of consumers and

*3). How we compute System Load Average *
We query the Mbean SysetmLoadAverage and divide it by the value of MBean
AvailableProcessors. Both of these MBeans are available under

I am not sure what is causing these regressions and would like your help in
understanding it. We are aware about the changes with respect to threading
model in the new broker, are there any design docs that we can refer to
understand these changes at a high level? Can we tune some parameters to
address these issues?


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