substack-concurrency-11.go

myPool := &sync.Pool{
    New: func() interface{}{
        fmt.Println("Creating new instance.")
        return struct{}{}
    }
}

myPool.Get() // no instance available, calls New;
instance := myPool.Get() // no instance available, calls New;
myPool.Put(instance) // instances in pool = 1
myPool.Get() // get instance from pool

// Creating new instance.
// Creating new instance.