ratelimits.md

golang.org rate limiter:

	rl := rate.NewLimiter(1000000, 1)
 
	last := time.Now()
	for i := 0; i < 10; i++ {
		rl.Wait(context.Background())
		cur := time.Now()
		fmt.Println("last", cur.Sub(last))
		last = cur
	}

Output:

last 16.038µs
last 11.367µs
last 4.051µs
last 4.582µs
last 2.146µs
last 3.085µs
last 2.173µs
last 3.121µs
last 1.984µs
last 3.09µs

uber-go rate limiter:

	rl := ratelimit.New(1000000, ratelimit.WithoutSlack)

	last := time.Now()
	for i := 0; i < 10; i++ {
		rl.Take()
		cur := time.Now()
		fmt.Println("last", cur.Sub(last))
		last = cur
	}

Output:

last 315ns
last 1.846µs
last 1.3µs
last 1.218µs
last 1.191µs
last 1.202µs
last 1.206µs
last 1.216µs
last 1.166µs
last 1.18µs

What about the context.Background() call? You're measuring that, too!

@tgulacsi context.Background returns a global variable, it doesn't really cost anything:
https://golang.org/src/context/context.go?s=7222:7247#L205

Just to confirm, I re-ran with the context.Backgroundout of the loop,

    ctx := context.Background()
    last := time.Now()
    for i := 0; i < 10; i++ {
        rl.Wait(ctx)
        cur := time.Now()
        fmt.Println("last", cur.Sub(last))
        last = cur
    }

And as expected, there's no performance difference:

last 19.098µs
last 9.628µs
last 4.207µs
last 2.839µs
last 2.767µs
last 2.619µs
last 4.12µs
last 2.977µs
last 3.946µs
last 2.535µs