web 性能压测工具

package main
import (
	"errors"
	"fmt"
	"github.com/golang/glog"
	"net/http"
	"sync"
	"time"
)
func main(){
	url := "http://www.baidu.com"
	count := 10
	workers := 10
	topK := 8
	ch := make(chan interface{}, workers)
	costs := make([]int, count)
	var wait sync.WaitGroup
	for i := 0; i < count; i++ {
		ch <- struct {}{}
		wait.Add(1)
		go func(i int) {
			defer func() {
				<- ch
				wait.Done()
			}()
			begin := time.Now().UnixNano()
			_, err := http.Get(url)
			if err != nil {
				glog.Error(err)
			}
			costs[i]= int(time.Now().UnixNano() - begin) / int(time.Microsecond)
		}(i)
	}
	wait.Wait()
	c, err := TopKByQuickSort(costs, topK)
	if err != nil {
		fmt.Println(err)
	}
	fmt.Printf("平均响应时间：%d \n", avg(costs))
	fmt.Printf("95%%响应时间 %d \n", c)
}
func avg(nums []int) int {
	total := 0
	for _, value := range nums {
		total += value
	}
	return total / len(nums)
}
func TopKByQuickSort(nums []int, k int) (int, error) {
	length := len(nums)
	if length < k {
		return 0, errors.New(fmt.Sprintf("nums length less then %d", k))
	}
	left := 0
	right := length
	pivotIndex := partition(nums, left, right)
	for pivotIndex != k {
		if pivotIndex < k {
			left = pivotIndex + 1
		} else {
			right = pivotIndex
		}
		pivotIndex = partition(nums, left, right)
	}
	return nums[k], nil
}
func partition(nums []int, left, right int) int {
	pivot := nums[left]
	pos := left
	for i := left; i < right; i++ {
		if nums[i] < pivot {
			nums[i], nums[pos] = nums[pos], nums[i]
			pos++
		}
	}
	return pos
}