[rabbitmq-discuss] Active/Active: shutdown of one service brings down the cluster

Vadim Chekan kot.begemot at gmail.com
Tue Feb 14 20:40:05 GMT 2012

Hi Simon,

Thanks for looking into the logs. Since we fixed channel leak in our
application we do not experience any problems anymore.

Regarding transient queues in HA. I am just not sure how system would
behave when non-HA queue is declared in a cluster environment.
Documentation describes in great details what happen to mirrored queues but
I can't find anything about non-ha queue in HA cluster. Queue will be
created on a single server, and application should be ready to re-declare
queue in case of failover. So far so good. But how does it work with load
balancer? When request is made against a server which does not have a given
queue, will the cluster "know" where the queue is and proxy the request to
the proper server?


On Mon, Feb 13, 2012 at 10:09 AM, Simon MacMullen <simon at rabbitmq.com>wrote:

> On 10/02/12 00:20, Vadim Chekan wrote:
>> I think we nailed down a problem. We had a channel leak in our
>> application. With ~50 connections we had >90 channels per connection and
>> growing. This definitely correlates to high CPU usage.
>> What I still do not understand either it triggered rabbit into unstable
>> state or it was something else. Maybe increasing latencies in message
>> handling triggered cluster members into flipping neighbor aliveness
>> status back and force? Just speculating here: could timeouts because of
>> high load cause network fragmentation, when every node temporally does
>> not see neighbors, becomes a master, than see a neighbor, freak out, etc?
> That's plausible, but I don't think that's what's happening (there's
> nothing about network partitioning in the logs).
>  I've attached logs from all 3 cluster members. They are polluted with
>> load balancer "ping".
> Thanks. I've had a poke at this but nothing is leaping out at me yet. I'll
> keep at it though.
> One thing that's a bit odd: you seem to be creating HA / transient /
> autodelete / exclusive queues. So although they're "HA", they will vanish
> if any of the following happens:
> * The entire cluster goes down (transient) or
> * All consumers for a queue cancel (autodelete) or
> * The connection that created them closes (exclusive)
> Is this intentional? It seems like an odd use of HA.
> Cheers, Simon
> --
> Simon MacMullen
> RabbitMQ, VMware


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