Pulp

To reproduce:

1. Start Pulp normally. I reproduced this on 2.6.4.
2. While Pulp is running, restart qpidd very often (every few seconds). I do that with this shell script:

while true
do sudo service qpidd restart
sleep 1.1
sleep $(($((RANDOM))%2))
done

3. Observe that over a few minutes the CPU will grow. You can watch this by periodically listing the processes and looking at the CPU column. I do this with

ps -awfux | grep celery

4. Once your processes are consuming lots of CPU for no apparent reason, stop the qpidd restart script and ensure that qpidd is started.
5. Observe that your CPU never goes back down even though Pulp is not doing any work and qpidd is running normally.
6. Despair

You can recover from this by restarting the celery processes. The original reporter who told me about this also indicated there was a memory leak, but I haven't confirmed this.