Setting up the configuration rpc_zmq_topic_backlog causing zmq receiver to silently ignore all messages

[Harish Kumar]

Setting up the configuration parameter rpc_zmq_topic_backlog causing zmq receiver to silently ignore all messages - I had run strace on nova-rpc-zmq-receiver, from where I see that, the issue was with one configuration option “rpc_zmq_topic_backlog”, due to which the code was silently returning without processing that message – there was no logs or no trace in the zmq receiver log even after enabling debug.

What I see is that this option is set in zmq_opts array in impl_zmq.py, but when a message come in, the class ZmqProxy check this config item , and the function __getattr__ in the class ConfigOpts (oslo/config/cfg.py) is raising error saying no such option and then return it without processing that message further.

If I just comment out the configuration entry, it just works fine.

Please see attachment for Strace output.

[John Garbutt (johngarbutt)]

Sounds like an oslo bug, rather than nova, but needs an experts eye

[Li Ma (nick-ma-z)]

I deployed a testbed with a given value for rpc_zmq_topic_backlog. It works.