应该使用基于例程/通道的机制替换并发映射吗？

Question

There's a map[PlayerId]Player to check whether player is online and perform state alterations knowing his ID. This must be done from multiple goroutines concurrently.

For now I plan to use streamrail's concurrent map, but what about a regular map and synchronization using channels?

• Should it always be preferred in Go?
• Should it be preferred in certain circumstances?
• Are they basically just two ways to accomplish the same thing?

BTW, I know the slogan:

don't communicate by sharing memory share memory by communicating

but there are locking mechanisms in stdlib and no words in docs about not using them at all.

Answer 1

Start with the simplest approach: a map and RWMutex.

I cannot recommend using concurrency library unless it is widely used and tested (see https://github.com/streamrail/concurrent-map/issues/6 for example).

Note that even if you use github.com/streamrail/concurrent-map you will still need to implement your own synhronisation (use RWMutex) in the following scenario:

if _, ok = m[k]; !ok {
   m[k] = newPlayer()
}

If your game is super popular and played by many players you will find that this approach doesn't scale but I would worry about it only if it becomes a problem.