[rabbitmq-discuss] Odd delay in federation exchanges being recognized

Matt Pietrek mpietrek at skytap.com
Thu Sep 6 17:18:05 BST 2012

Thanks Simon.

I agree, it's odd. I'll keep an eye out for further clues if/when I see it
again. I mostly wanted to know if there was something obvious to you folks.
For instance (totally a stab in the dark here...) perhaps connections
between federated brokers taking a long time to establish.


On Thu, Sep 6, 2012 at 2:58 AM, Simon MacMullen <simon at rabbitmq.com> wrote:

> That... certainly sounds very odd.
> So the "unknown exchange type" message is what you get when you declare an
> exchange using a plugin, and then remove that plugin.
> So could the exchange type be getting registered slowly somehow? Hard to
> believe, the registration happens during startup, and RabbitMQ shouldn't be
> able to get to the point where it's accepting connections without all
> exchange types being registered.
> I'll have a look at that code in case anything jumps out, but it's pretty
> simple so don't hold your breath...
> Cheers, Simon
> On 05/09/2012 7:27PM, Matt Pietrek wrote:
>> Let me admit up front that this is a weird one, but I'll press ahead on
>> the chance there's something there.
>> I've got two brokers I'm using the federation plugin with. I create a
>> single exchange 'skytap' on each broker, and make the 'skytap' exchange
>> on the other broker its upstream.
>> I create the rabbitmq.config file dynamically before starting each
>> broker. Starting from a blank slate (blowing away the mnesia directory),
>> I launch the two nodes concurrently.
>> When I go to the Exchange tab in either broker, I see two Exchanges as
>> expected:
>>   * federation: skytap -> rabbit at mq2.skytap.com
>>     <mailto:rabbit at mq2.skytap.com> B
>>   * skytap
>> The type of the exchanges is x-federation-upstream and x-federation,
>> respectively. However, when first starting up, the type column is a red
>> color indicating a problem, and hovering over it, I get a message to the
>> effect of "unknown exchange type x-federation. Messages published to
>> this exchange won't work."
>> Now, here's the interesting thing: I*f I wait long enough (usually
>> around 10-15 minutes) **and without doing anything, the error state
>> eventually goes away* and the Exchanges seem happy. This has happened at
>> least three times, so it doesn't seem like a random fluke or that I
>> accidentally did something.
>> Here's my config file, FWIW...
>> [
>> {rabbit, [{cluster_nodes, [rabbit at mq1]}, {disk_free_limit, 104857600}]},
>> {mnesia, [{debug, trace}]},
>> {rabbitmq_federation, [{exchanges, [[{type, "topic"}, {upstream_set,
>> "skytap_upstreams"}, {virtual_host, "/"}, {exchange, "skytap"}]]},
>> {upstream_sets, [{"skytap_upstreams", [[{connection, "upstream-mq2"},
>> {max_hops, 1}, {exchange, "skytap"}]]}]},
>> {connections, [{"upstream-mq2", [{host, "mq2"}, {port, 5672}]}]}]}
>> ].
>> Again, I realize this sounds a bit wonky, but it's happened enough times
>> to make me not think I'm crazy.
>> Thanks,
>> Matt
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