Amqp: Question: Is it safe to share channels/connections across goroutines?

[cenkalti]

[streadway]

The types in this library are designed to be safe to used from multiple goroutines, though it's generally simpler to keep a single goroutine that manages the IO to the broker and communicate into or out of your AMQP logic with a chan in a type relevant to your application.

[cenkalti]

Thanks for the answer.

[michaelklishin]

@cenkalti publishing from multiple goroutines on the same channel is not safe.
To be more specific: every time you publish a non-empty message,
the client sends 3 (or more) frames on the wire:

[method: basic.publish] [content headers] [content body]+

When publishing on the same channel from multiple threads/goroutines/processes,
you may end up with incorrect interleaving, e.g.

[method: basic.publish] [content headers] [method: basic.publish] [content body] [content headers] [content body]

RabbitMQ won't be able to parse this frame sequence and raises a fatal error. The solution
is to either

• Avoid publishing on _the same_ channel from multiple threads/goroutines/processes
• Synchronize publishing in your own code

[streadway]

@michaelklishin the interleaving of frames from different threads on the same channel is a concern for most library implementations. This library serializes sends until all frames are delivered whether it's a method with content or not.

This is the mutex: https://github.com/streadway/amqp/blob/master/channel.go#L206 that ensures all frames for a publishing are written before the next send is begun per channel.

This test uses multiple goroutines to deliver a payload that would need to be split across multiple body frames over the same channel: https://github.com/streadway/amqp/blob/master/client_test.go#L466