Set prefetch/QoS across all Channels from the server side?

[Gavriel Fishel]

Hello Rabbitmq-users!

I have an issue with producers creating channels without QoS causing tons of "unacked messages" by slow consumers.

I can't control what the producers or consumers do as I'm the one responsible for the RabbitMQ server / policies.

 

The "unacked messages" pile up and cause lots of memory issues.

Is there a way I can enforce "Prefetch" or "QoS" across all Channels?

If it's controlled only from the service side, what other measures can I do to protect the server? ("max-length" and "ttl" work only on "ready messages").

Thanks,

Gavriel

[Luke Bakken]

Hello,

There is no way to enforce QoS or a limit on un-acked messages from the server. You will have to ensure applications are written correctly.

Thanks,

Luke

[Gavriel Fishel]

Thanks for the answer!

BR,
Gavriel

[Johan Rhodin]

Hi,

Maybe not enforce but at least a default:

You can use: default_consumer_prefetch

{rabbit, [{default_consumer_prefetch, {true, 5}}]}

See https://github.com/rabbitmq/rabbitmq-server/pull/1408

You can combine that with channel_max and the new in 3.7 vhost connection/queue limits.

/Johan

[Gavriel Fishel]

Thanks for the info but im not sure it helped :(

I run on every node:
rabbitmqctl eval 'application:set_env(rabbit, default_consumer_prefetch, {true, 50}).'

And I still have over 20K unacked messages
also the "Global prefetch count" and "prefetch count" are still "0"

See attached screenshot

[Luke Bakken]

Hello Gavriel,

You will have to make that setting in your configuration file and restart RabbitMQ.

Thanks,

Luke

[Gavriel Fishel]

Thanks for the help!

Gavriel