Mojolicious and RabbitMQ

[Bakanov Dmitriy]

Hello, community

Currently I have 2 Mojolicious applications. I want first application notify second application about some messages it receives. I decided, that RabbitMQ will be the best way to implement it, because RabbitMQ tool is widespread, it has monitoring features, it's fast and allow flexibility. But, I have some troubles to use RabbitMQ from mojolicious. There are clients to RabbitMQ that allow non-blocking mode, but due to company's coding standards I don't want to use unsupported client like AnyEvent::RabbitMQ. Now I have the following Idea:
1. I found a client https://github.com/markwellis/net-amqp-rabbitmq that has some support and has commits in a recently few months
2. Unfortunately, it's blocking.
3. But I can call method 'get' to get messages from RabbitMQ if they exist, or it will return undef, if there no messages
4. I want to emit event 'receiving' in IOLoop and call Rabbit's 'get' method.
5. If there is a message I will emit 'received' event in IOLoop and then will be handle it in callback.
6. After this handling I will emit 'receiving' again.
7. If there are no messages in 'receiving' call, I will start IOLoop's timer to fire after 0.1 sec and emit 'receiving' in timer's callback
8. So, I will have the system, that works non-blocking, using blocking library (?)
9. But I will have some overhead when RabbitMQ is idle, and I will be check it every 0.1 sec. I think it's not a problem for me, because RabbitMQ always should have a load in production. I did measured, that idle Mojolicious in this 'receiving' mode don't consume much resources. Just a 1-2% of CPU. But again, I think it really never will be idle.

QUESTION: Do you see some pitfalls in this schema I have described? Is it OK?
QUESTION 2: Maybe some advices to use another configuration or instruments to achieve my goals?

Thanks,
Dmitry

[Denis Fedoseev]

Hi, Dmitry

What problem with AnyEvent::RabbitMQ do you have? Right now, I see that this module is updated 21th of march and it doesn't looks like unsupported.

Anyway, blocking library in non-blocking system is not a problem. But you should understand that is a potential bottleneck in whole application. Because if this library blocks - all your apllication will blocks.

For example, if single request costs 1ms and you have 10rps - your application will locks for 10ms. But, if one of requests is longer than 1s - you will have the DOS.

Best regards,
Denis

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С уважением, Денис Федосеев

[Bakanov Dmitriy]

Thanks, now I see it's currently supported by bobtfish. If you use it in production, could you please share your impressions?

пятница, 5 июня 2015 г., 12:24:53 UTC+5 пользователь alpha6 написал:

[Denis Fedoseev]

Sorry, I don't use Mojo and RabbitMQ together.

[Sebastian Podjasek]

If you're still interested in using RabbitMQ with Mojo, please take a look at this:

https://github.com/InWayOpenSource/mojo-rabbitmq-client

I just started to rewrite AnyEvent::RabbitMQ to work on Mojo::IOLoop and Mojo::EventEmitter.
Any help or criticism would be greatly appreciated.