[rabbitmq-discuss] Connection is always in "flow" State.

Jason McIntosh mcintoshj at gmail.com
Thu Jul 10 15:31:09 BST 2014


Just a quick confirmation on this.  The documentation states that flow
control is:

   - A per-connection mechanism that prevents messages being published
   faster than they can be routed to queues.
   - A global mechanism that prevents any messages from being published
   when the memory usage <http://www.rabbitmq.com/memory-use.html> exceeds
   a configured threshold or free disk space drops below a configured
   threshold.

In my testing, I've actually seen this as well - where messages can backlog
(so far seems to the point of available resources), while a consumer is
chugging along at half the publish speed.  SO is flow control also
triggered by consumer processing?  At what point does consumer handling
trigger flow control if so?  Just looking for a little bit of clarification
on this - I'm guessing there's some internal logic someplace I'm missing on
this,
Thanks!
Jason


On Tue, Jul 8, 2014 at 3:33 AM, Michael Klishin <mklishin at gopivotal.com>
wrote:

>
>
> On 8 July 2014 at 07:49:26, Lost (w_pg at qq.com) wrote:
> > > I have a client to publish message to rabbitmq(1 connection
> > and 1 channel, in same machine with rabbitmq), no consumer.
> > Message rates is 2000/s ~ 3000/s
> > Traffic is 300Kb/s ~ 750kB/s
> > The channel state is "running", but the connection state is always
> > "flow".
> > I found erl.exe cpu is only 5% ~ 10%, but why connection is in "flow"
> > state?
>
> Flow control does not depend on CPU usage but rather whether consumers
> can keep up with producers. Try adding a consumer.
> --
> MK
>
> Staff Software Engineer, Pivotal/RabbitMQ
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-- 
Jason McIntosh
https://github.com/jasonmcintosh/
573-424-7612
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