[LRUG] AMQP threads. Where did my messages go?

[Steve]

*"On my production servers, the job is queued in RabbitMq, processed
perfectly and the notification is published apparently."*

Is this apparent because you have acknowledgements on the RabbitMQ server
for the sent messages?
I believe the ACK config and UI for RabbitMQ will report what was sent and
received using acknowledgements from the client.


On 21 March 2014 11:47, Simon Morley <simon at polkaspots.com> wrote:

> Morning All
>
> Having asked SO, I remembered we were supposed to be encouraging more
> questions here! I hope you can help (sorry this is a long message).
>
> Relatively new to the world of RabbitMQ, I'm getting stuck debugging the
> problem of missing messages. All was / is fine in my dev. environment, the
> problems arise when we start chucking thousand of messages at things.
>
> I've narrowed the problem down to messages that are sent from within
> another job. For example, we have a job that moves a customer's
> subscription when they sign up. We publish this to our rabbit servers using
> the AMQP gem and EM using something like this:
>
> https://gist.github.com/simonmorley/9684010
>
> def queue_process_subscription
>    user. process_subscription
> end
>
> def process_subscription
>   hammer_time
>   MESSAGE_QUEUE.push(json_message, 'ps.routing.key')
> end
>
> After the job's been completed, we use MESSAGE_QUEUE to push a message to
> our notification servers (which run NodeJS, node-amqp and SocketIO).
>
> On my lonely laptop, the jobs process perfectly, the notification are sent
> and my SocketIO client receives them. Happy days.
>
> On my production servers, the job is queued in RabbitMq, processed
> perfectly and the notification is published apparently. The problem is, it
> doesn't appear to be received by the node amqp consumer 100% of the time.
> Maybe 1 in 10 get delivered (and sometimes they don't look like the full
> message). The rest just vanish.. It gets worse as we load the servers up.
>
> I thought it was the AMQP on the Node servers but I created a loop to run
> MESSAGE_QUEUE 10,000 times and they were all consumed..
>
> So, I'm assuming the problem is that we're sending a message from within
> another thread. At least, that's what I think it is. My knowledge of such
> things has now come to an end...
>
> We've now replaced the last notification with Redis publish which works a
> treat. But that's another cog to think about.
>
> Like I said, I'm new to this messaging / threading stuff,  and would
> appreciate it if someone can point me in the right direction, tell me what
> to read or suggestion something else to try. Or tell me to give up and go
> home.
>
> Cheers
>
> Simon
>
>
>
> Simon Morley
> Big Chief | PolkaSpots Supafly Wi-Fi
>
> simon at PolkaSpots.com
> 020 7183 1471
> @polkaspots
>
>
>
>
>
>
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