限流
https://github.com/uber-go/ratelimit
import (
"fmt"
"time"
"go.uber.org/ratelimit"
)
func main() {
rl := ratelimit.New(100) // per second
prev := time.Now()
for i := 0; i < 10; i++ {
now := rl.Take()
fmt.Println(i, now.Sub(prev))
prev = now
}