Doesn't quorum queue support idle_since in management plugin?

[Peter]

Hello,

When I requested the quorum queue using /api/queues, the idle_since field does not exist, so the queue always comes out as running.

here is)
curl -s -u id:pw http://localhost:15672/api/queues

i can't find idle_since.
Doesn't quorum queue support idle_since in management plugin?

thank you.

[Michal Kuratczyk]

Hi,

Yes, quorum queues currently don't expose this metric (this metric is related to Erlang process hibernation and quorum queues don't hibernate).

What do you use this metric for?

Best,

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Michał

RabbitMQ team

[Peter]

Thanks for answer.

As I understand it, when the queue status tab shows running, it means queue producing and consuming.

but when quorum queue not doing anything, it only shows runing. ( in rabbitmq web-management(localhost:15672) )

so i wonder when the quorum queue becomes idle.( in rabbitmq web-management(localhost:15672) )

Best,

2022년 11월 17일 목요일 오전 2시 40분 31초 UTC+9에 mkura...@gmail.com님이 작성:

[Michal Kuratczyk]

Hi,

It depends on the definition of "idle". :) There is no universally accepted definition of an idle queue, it's just that years ago someone on the RabbitMQ

team decided that after 5 seconds of idleness (no new messages being published to the queue and no consumers receiving messages from the queue),

the queue is marked as idle and the Erlang process for this queue is hibernated to save some resources (you can learn more about this

in Erlang's documentation: https://www.erlang.org/doc/man/erlang.html#hibernate-3)

5 seconds is a completely arbitrary value. For example, if you run "perf-test -ad false -f persistent -qa x-queue-version=2 -u cq -c 1 -P 4"

(using https://perftest.rabbitmq.com/), a message is published every 4 seconds, so the queue will never be marked as idle, even though

it's idle almost all the time (accepting the message and delivering it to the user takes a fraction of a second and for the rest of the time,

this queue process has nothing to do).

The same queue would be marked as idle often, if you published at a slightly lower frequency.

Quorum queues currently never hibernate. It's just a technical decision that can be revisited in the future. As with everything, it's a trade-off:

you save some resources while a process is idle, but you increase the latency when a message is published to a hibernated queue and you risk

a lot of additional work in some scenarios (eg. some users have large fan-out use cases: a message is delivered to many queues at the same time,

if all those queues are hibernated when this happens, there will be a sudden increase in resource usage when all of them are de-hibernated to accept the message).

If you are interested in the metric or hibernation of quorum queues, please share some details of your scenario and what you'd use this metric for.

Best,

To view this discussion on the web, visit https://groups.google.com/d/msgid/rabbitmq-users/64b9a4b8-9d7a-43c1-b6ec-bfd3da8aff04n%40googlegroups.com.

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Michał

RabbitMQ team

[Peter]

Thank you for your kind and detailed reply.

Can I refer the code for this explanation?

===

There is no universally accepted definition of an idle queue, it's just that years ago someone on the RabbitMQ

team decided that after 5 seconds of idleness (no new messages being published to the queue and no consumers receiving messages from the queue),

the queue is marked as idle and the Erlang process for this queue is hibernated to save some resources

===

I would like to see implemented code in github.

Best,

2022년 11월 17일 목요일 오후 5시 56분 28초 UTC+9에 mkura...@gmail.com님이 작성:

[Michal Kuratczyk]

You can start here:

https://github.com/rabbitmq/rabbitmq-server/blob/main/deps/rabbit/src/rabbit_amqqueue_process.erl#L1779-L1796

To view this discussion on the web, visit https://groups.google.com/d/msgid/rabbitmq-users/ef0a6314-2ef1-4be7-835d-91a365d6332fn%40googlegroups.com.

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Michał

RabbitMQ team