Probably wouldn't do this unless you really needed to; nbd workloads are probably easier than HTTP workloads (a single NBD "mount" might have lots of connections, but you're not adding and removing hundres of connections per second).
You might be right. Different workloads will definitely have different effects. That said, implementing the gnet api is pretty easy and doesn't require a huge context switch. It is worth a test to see which one performs better.
I used it for a tcp connection (json-rpc) workload and it was far better and the code was cleaner.
Right, I don't want to talk down gnet, it's neat, but you're basically writing non-idiomatic libevent-style networking code --- ie, very non-idiomatic Go code --- and it seems to me like most of the perf win here is minimizing the number of goroutines you have serving blocking operations, which is not really a problem you're going to have with an NBD implementation.
I see your point. In my case it was basically a proxy concentrator. On one side, accept and hold open a huge number of connections, then maintain a single open connection on the other side. It worked really well for this situation.
