[rabbitmq-discuss] QueueingConsumer basicPublish safety

Thu Jul 29 17:11:28 BST 2010

> Channel.flow has been asserted and therefore the basic.publish call has
> blocked. We are aware that our API documentation is incorrect in
> claiming that basic.publish is safe to use in the given context. This
> will be updated.

So this probably only happens when rabbit thinks it's overloaded?

> You need to enable consumption of messages while publishers are
> potentially blocked. This will allow memory pressure on the broker to be
> relieved and publishers to resume eventually. In your example
> consumption and publication happens in the same thread and therefore
> your application gets completely stuck as soon as publication blocks.

So is it safe to publish messages on a channel when some other thread
is consuming on that channel?  If I acquire a lock on the channel in a
different thread, and the channel blocks in basicPublish, will that
still allow new messages to be delivered to the consumer?

> You could also consider using separate channels for publishing and
> consuming messages.

I'm currently doing acks and publishes in a transaction, but I'm not
sure if that's entirely necessary.  It's certainly convenient and
safe, but I don't know that I really need to do it.  Are acks
guaranteed not to block the way that publishes do?  I obviously can't
send my acks on a different channel :)