dubbo-go中leastActiveLoadBalance的用法

这篇文章主要介绍"dubbo-go中leastActiveLoadBalance的用法"，在日常操作中，相信很多人在dubbo-go中leastActiveLoadBalance的用法问题上存在疑惑，小编查阅了各式资料，整理出简单好用的操作方法，希望对大家解答"dubbo-go中leastActiveLoadBalance的用法"的疑惑有所帮助！接下来，请跟着小编一起来学习吧！

序

本文主要研究一下dubbo-go的leastActiveLoadBalance

leastActiveLoadBalance

dubbo-go-v1.4.2/cluster/loadbalance/least_active.go

const (        // LeastActive ...        LeastActive = "leastactive")func init() {        extension.SetLoadbalance(LeastActive, NewLeastActiveLoadBalance)}type leastActiveLoadBalance struct {}// NewLeastActiveLoadBalance ...func NewLeastActiveLoadBalance() cluster.LoadBalance {        return &leastActiveLoadBalance{}}

• leastActiveLoadBalance的NewLeastActiveLoadBalance方法创建leastActiveLoadBalance

Select

dubbo-go-v1.4.2/cluster/loadbalance/least_active.go

func (lb *leastActiveLoadBalance) Select(invokers []protocol.Invoker, invocation protocol.Invocation) protocol.Invoker {        count := len(invokers)        if count == 0 {                return nil        }        if count == 1 {                return invokers[0]        }        var (                leastActive  int32                = -1 // The least active value of all invokers                totalWeight  int64                     // The number of invokers having the same least active value (LEAST_ACTIVE)                firstWeight  int64                     // Initial value, used for comparison                leastCount   int                       // The number of invokers having the same least active value (LEAST_ACTIVE)                leastIndexes = make([]int, count)      // The index of invokers having the same least active value (LEAST_ACTIVE)                sameWeight   = true                    // Every invoker has the same weight value?        )        for i := 0; i < count; i++ {                invoker := invokers[i]                // Active number                active := protocol.GetMethodStatus(invoker.GetUrl(), invocation.MethodName()).GetActive()                // current weight (maybe in warmUp)                weight := GetWeight(invoker, invocation)                // There are smaller active services                if leastActive == -1 || active < leastActive {                        leastActive = active                        leastIndexes[0] = i                        leastCount = 1 // next available leastIndex offset                        totalWeight = weight                        firstWeight = weight                        sameWeight = true                } else if active == leastActive {                        leastIndexes[leastCount] = i                        totalWeight += weight                        leastCount++                        if sameWeight && (i > 0) && weight != firstWeight {                                sameWeight = false                        }                }        }        if leastCount == 1 {                return invokers[0]        }        if !sameWeight && totalWeight > 0 {                offsetWeight := rand.Int63n(totalWeight) + 1                for i := 0; i < leastCount; i++ {                        leastIndex := leastIndexes[i]                        offsetWeight -= GetWeight(invokers[i], invocation)                        if offsetWeight <= 0 {                                return invokers[leastIndex]                        }                }        }        index := leastIndexes[rand.Intn(leastCount)]        return invokers[index]}

• Select方法遍历invokers，挨个通过protocol.GetMethodStatus(invoker.GetUrl(), invocation.MethodName()).GetActive()获取active信息，并通过GetWeight(invoker, invocation)获取weight，然后计算leastCount、totalWeight、sameWeight；对于leastCount为1的返回invokers[0]，对于sameWeight为false且totalWeight大于0的，遍历leastIndexes，计算offsetWeight，若offsetWeight小于等于0，则返回invokers[leastIndex]，否则通过leastIndexes[rand.Intn(leastCount)]计算index，返回invokers[index]

GetWeight

dubbo-go-v1.4.2/cluster/loadbalance/util.go

// GetWeight ...func GetWeight(invoker protocol.Invoker, invocation protocol.Invocation) int64 {        url := invoker.GetUrl()        weight := url.GetMethodParamInt64(invocation.MethodName(), constant.WEIGHT_KEY, constant.DEFAULT_WEIGHT)        if weight > 0 {                //get service register time an do warm up time                now := time.Now().Unix()                timestamp := url.GetParamInt(constant.REMOTE_TIMESTAMP_KEY, now)                if uptime := now - timestamp; uptime > 0 {                        warmup := url.GetParamInt(constant.WARMUP_KEY, constant.DEFAULT_WARMUP)                        if uptime < warmup {                                if ww := float64(uptime) / float64(warmup) / float64(weight); ww < 1 {                                        weight = 1                                } else if int64(ww) <= weight {                                        weight = int64(ww)                                }                        }                }        }        return weight}

• GetWeight方法通过url.GetMethodParamInt64(invocation.MethodName(), constant.WEIGHT_KEY, constant.DEFAULT_WEIGHT)获取weight，若weight大于0，则计算warmup，重新计算weight值

小结

leastActiveLoadBalance的NewLeastActiveLoadBalance方法创建leastActiveLoadBalance；Select方法遍历invokers，挨个通过protocol.GetMethodStatus(invoker.GetUrl(), invocation.MethodName()).GetActive()获取active信息，并通过GetWeight(invoker, invocation)获取weight，然后计算leastCount、totalWeight、sameWeight，最后计算index

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