AMPQ broker connection reusing

[requilence]

Is there a reason to open/close broker connection on every message publishing?
In a single goroutine with AMPQ connection reusing I have 110 msg publish/sec vs 55 msg/sec with current implementation.
Also with using of goroutines to publish messages I was able to get 34000 msg/sec on the same configuration. Looks like goroutines is safe when reusing AMPQ connection

[RichardKnop]

@requilence Hi Roman. There is no specific reason for it. You can submit a PR if you want. I'm a bit busy at the moment but performance improvements like this are needed. The way I did it was the easiest implementation but it would be much better to reuse connections.

[requilence]

@RichardKnop Ok, I will test my solution and if everything works great I will create PR.

[wizard580]

@requilence
Can you show your solution? I'll try to test it.

[requilence]

@wizard580 #36

[mission-liao]

I've working on some go-amqp stuff (another worker queue project) and found this (issue)[https://github.com/streadway/amqp/issues/119] in that project. Quote from one discussant:

I personally saw massive performance improvements by using a channel per go routine. 

In current implementation of machinery, we create a channel (and connection) per 'SendTask', it seems a reasonable implementation, or maybe we would at least maintain a 'channel pool' for each request from different go routine.

[requilence]

@mission-liao Also the similar approach is using in https://github.com/go-mgo/mgo.
Initially I made the same decision (reusing connection, reinit channel) but doesn't see any performance benefits from this. I will repeat tests today and come back with results

[RichardKnop]

Great work and investigation guys. It seems reusing channels might be the way to go.