Golang加權(quán)輪詢負載均衡的實現(xiàn)

更新時間：2021年06月18日 11:34:11 作者：銳玩道

負載均衡器在向后端服務(wù)分發(fā)流量負載時可以使用幾種策略。本文主要介紹了Golang加權(quán)輪詢負載均衡，具有一定的參考價值，感興趣的小伙伴們可以參考一下

實現(xiàn)加權(quán)輪詢負載均衡思路

代碼實現(xiàn)一個加權(quán)負載均衡

Weight 初始化時對節(jié)點約定的權(quán)重
currentWeight 節(jié)點臨時權(quán)重，每輪都會變化
effectiveWeight 節(jié)點有效權(quán)重，默認與Weight相同
totalWeight 所有節(jié)點有效權(quán)重之和：sum(effectiveWeight)

代碼實現(xiàn)一個加權(quán)負載均衡

currentWeight = currentWeight+effecitveWeight
選中最大的 currentWeight 節(jié)點為選中節(jié)點
currentWeight = currentWeight-totalWeight (4+3+2=9)

所以我們能夠在表格模擬運行情況：

請求次數(shù)	請求前currentWelght	選中的節(jié)點	請求后currentWelght
1	[serverA=4,serverB=3,serverC=2]	serverA	[serverA=-1,serverB=6,serverC=4]
2	[serverA=-1,serverB=6,serverC=4]	serverB	[serverA=3,serverB=0,serverC=6]
3	[serverA=3,serverB=0,serverC=6]	serverc	[serverA=7,serverB=3,serverC=-1]
4	[serverA=7,serverB=3,serverC=-1]	serverA	[serverA=2,serverB=6,serverC=1]
5	[serverA=2,serverB=6,serverC=1]	serverB	[serverA=6,serverB=0,serverC=3]
6	[serverA=6,serverB=0,serverC=3]	serverA	[serverA=1,serverB=3,serverC=5]
7	[serverA=1,serverB=3,serverC=5]	serverc	[serverA=5,serverB=6,serverC=-2]

加權(quán)輪詢負載均衡代碼

package load_balance

import (
 "errors"
 "strconv"

)

type WeightRoundRobinBalance struct {
 curIndex int
 rss      []*WeightNode
 rsw      []int

 //觀察主體
 conf LoadBalanceConf
}

// 配置主題
type LoadBalanceConf interface {
 GetConf() []string
 WatchConf()
 UpdateConf(conf []string)
}

type WeightNode struct {
 addr            string // 服務(wù)器地址
 weight          int //權(quán)重值
 currentWeight   int //節(jié)點當(dāng)前權(quán)重
 effectiveWeight int //有效權(quán)重
}

func (r *WeightRoundRobinBalance) Add(params ...string) error {
 if len(params) != 2 {
  return errors.New("param len need 2")
 }
 parInt, err := strconv.ParseInt(params[1], 10, 64)
 if err != nil {
  return err
 }
 node := &WeightNode{addr: params[0], weight: int(parInt)}
 node.effectiveWeight = node.weight
 r.rss = append(r.rss, node)
 return nil
}

func (r *WeightRoundRobinBalance) Next() string {
 total := 0
 var best *WeightNode
 for i := 0; i < len(r.rss); i++ {
  w := r.rss[i]
  //step 1 統(tǒng)計所有有效權(quán)重之和
  total += w.effectiveWeight

  //step 2 變更節(jié)點臨時權(quán)重為的節(jié)點臨時權(quán)重+節(jié)點有效權(quán)重
  w.currentWeight += w.effectiveWeight

  //step 3 有效權(quán)重默認與權(quán)重相同，通訊異常時-1, 通訊成功+1，直到恢復(fù)到weight大小
  if w.effectiveWeight < w.weight {
   w.effectiveWeight++
  }
  //step 4 選擇最大臨時權(quán)重點節(jié)點
  if best == nil || w.currentWeight > best.currentWeight {
   best = w
  }
 }
 if best == nil {
  return ""
 }
 //step 5 變更臨時權(quán)重為 臨時權(quán)重-有效權(quán)重之和
 best.currentWeight -= total
 return best.addr
}

func (r *WeightRoundRobinBalance) Get(key string) (string, error) {
 return r.Next(), nil
}

func (r *WeightRoundRobinBalance) SetConf(conf LoadBalanceConf) {
 r.conf = conf
}

測試代碼

package load_balance

import (
 "fmt"
 "testing"
)

func TestLB(t *testing.T) {
 rb := &WeightRoundRobinBalance{}
 rb.Add("127.0.0.1:2003", "4") //0
 // rb.Add("127.0.0.1:2004", "3") //1
 rb.Add("127.0.0.1:2005", "2") //2

 fmt.Println(rb.Next())
 fmt.Println(rb.Next())
 fmt.Println(rb.Next())
 fmt.Println(rb.Next())
 fmt.Println(rb.Next())
 fmt.Println(rb.Next())
 fmt.Println(rb.Next())
 fmt.Println(rb.Next())
 fmt.Println(rb.Next())
 fmt.Println(rb.Next())
 fmt.Println(rb.Next())
 fmt.Println(rb.Next())
 fmt.Println(rb.Next())
 fmt.Println(rb.Next())
}

測試結(jié)果

$ go test
127.0.0.1:2003
127.0.0.1:2005
127.0.0.1:2003
127.0.0.1:2003
127.0.0.1:2005
127.0.0.1:2003
127.0.0.1:2003
127.0.0.1:2005
127.0.0.1:2003
127.0.0.1:2003
127.0.0.1:2005
127.0.0.1:2003
127.0.0.1:2003
127.0.0.1:2005
PASS
ok gateway/_test/demo 0.080s

## 127.0.0.1:2003 為 127.0.0.1:2005 權(quán)重兩倍。而從答應(yīng)結(jié)果上看，符合要求