Go Optimizations 101

[ivanburak]

3.9 Use value cache pool to avoid some allocations

You write:

Personally, I find the design of sync.Pool seldom satisfies the needs in practice. So I often use
custom value cache pool implementations in my Go projects.

Could you give some examples of your custom value cache pool?

[go101]

The example above the quoted text shows how to use the custom value cache pool.
It is very simple, but it does show the whole mechanism.

import "container/list"

var npcPool = struct {
	sync.Mutex
	*list.List
}{
	List: list.New(),
}

func newNPC() *NPC {
	npcPool.Lock()
	defer npcPool.Unlock()
	if npcPool.Len() == 0 {
		return &NPC{}
	}
	return npcPool.Remove(npcPool.Front()).(*NPC)
}

func releaseNPC(npc *NPC) {
	npcPool.Lock()
	defer npcPool.Unlock()
	*npc = NPC{} // zero the released NPC
	npcPool.PushBack(npc)
}

[go101]

I will add a generic version when Go 1.18 is released.