限制速率

---

package main

import (
	"fmt"
	"github.com/gocolly/colly"
	"github.com/gocolly/colly/debug"
)

func main() {
	url := "https://httpbin.org/delay/2"

	// 实例化一个 collector
	c := colly.NewCollector(
		// 打开异步请求
		colly.Async(true),
		// 关联 debugger
		colly.Debugger(&debug.LogDebugger{}),
	)

	c.Limit(&colly.LimitRule{
		DomainGlob:  "*httpbin.*",
		Parallelism: 2,
		//Delay:      5 * time.Second,
	})

	// 4线程开始爬取 https://httpbin.org/delay/2
	for i := 0; i < 5; i++ {
		c.Visit(fmt.Sprintf("%s?n=%d", url, i))
	}
	// 等待线程结束
	c.Wait()
}