allow payload length filtering

[norman shen]

In one of our production environment, I saw unexpected long notification from cinder backup. It is mainly caused by cinder backup is backing up a very huge volume (>1T) and got too many slices (object size is 48MB configured).

Rabbitmq had hard time handling very large objects and what's worse is that we are using a mirroring queue setup.

So I thinking if it is possible to create a filter which will filter out unexpected message passed by program, by doing this in oslo.messaging, individual users do not have to implement their own logics.

[Ken Giusti (kgiusti)]

> Rabbitmq had hard time handling very large objects and what's worse is that we are using a mirroring queue setup.

How does the failure manifest? RPC timeout/call failure?

What will happen if the messages are filtered? Won't that result in an RPC timeout/call failure as well?

I'm not sure that adding a filter feature to oslo.messaging will provide any value here.

Since 3.8+ (IIUC) rabbitmq has a configurable maximum message size (up to 512MB per message). What happens if the size limit is set in rabbitmq to < 48BM? Does that effectively do the same thing as having a filter in oslo.messaging?

Can the cinder object size be reduced?

[Ken Giusti (kgiusti)]

For reference:

https://github.com/rabbitmq/rabbitmq-server/pull/1812
https://github.com/rabbitmq/rabbitmq-server/commit/4876e9346d7cb82da594b7831c0ef8bd194a03cf