Suggestion: per queue message size limit

[johanrhodin]

An operator can limit the global message size with max_message_size. For some environments this is too broad. A user might want to limit the message size in more detail for only some queues (such as quorum queues), but not other queues (classic queues, streams), or for queues A, B, C, but not D. This could be designed as a policy.

Before doing a full implementation we (CloudAMQP) wanted to check if there are any opinions on this in the community.

[michaelklishin]

I don't remember seeing similar requests.

max_message_size is enforced by channels (rabbit_channel:check_msg_size/2) and AMQP 1.0 sessions (rabbit_amqp_session:handle_control/1), neither of which is queue (at the time of limit enforcement) or policy aware.

Enforcing limits at the queue level means risky changes to the queue <=> channel communication "protocol" and to me, the benefit does not seem to be worth that risk.

[michaelklishin]

One variation of this that would be easy to implement with no risks that I can think of is a virtual host-level limit. Channels and AMQP 1.0 sessions can fetch it when they initialize.