[rabbitmq-discuss] flow control blocked producers vs consumers

Kobi Biton kbiton at outbrain.com
Mon Aug 5 07:58:07 BST 2013

you are 100% right after a cerfull look consumers (which are on a
separated channels) were not blocked , the problem was the producers
which flow control blocks.
That said the results of blocked producers , I will execute the
rabbitmqctl report when the problem reproduces and share this.

Our current suspicion is that the consumers cannot write fast enough
to the graphite thus slowing down the producers until they get


On Fri, Aug 2, 2013 at 5:24 PM, Emile Joubert <emile at rabbitmq.com> wrote:
> On 26/07/13 12:39, Kobi Biton wrote:
>> Our logstash consumers do use their own connection , we do not use the
>> same connection for publishing (logstash rabbitmq output) and for
>> consuming (logstash rabbitmq input) , I was under the impression that
>> the consumers are blocked due to the fact that when rabbitmq starts to
>> block producers due to flow rates looking at the logstash consumers
>> logs I see errors connecting to the broker (connection reset by host)
>> which implies that the broker rejects the consumers connection this of
>> course leads us to shaky state where messages are no delivered and the
>> only workaround we found is capturing the blocked producers list from
>> rabbitmq_ctl and restarting the logstash agents by looping on all the
>> blocked producers.
> If publishers and consumers use separate connections then blocking of
> publishers due to flow control won't affect consumers directly. Though
> if publishers slow down that will eventually slow down consumers too
> when queues are empty.
> Can you explain what you mean when you say consumers are blocked? Are
> there messages available in queues that are not being delivered? It
> should be possible to determine the reason for messages not being
> delivered if you provide the output of "rabbitmqctl report".
> -Emile

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