xfy
c6e7091089
filterHealthy() allocated 2 slices (available + backups) per call. filterHealthyAndExclude() allocated 3 (adds excludeSet map). IPHash allocated fnv.New64a() object per call. All triggered on every request's LB selection. Changes: - Add filterContext struct holding reusable buffers, managed by sync.Pool - Replace filterHealthy → filterInto (writes into pooled buffers) - Replace filterHealthyAndExclude → filterIntoExcluding (pooled buffers) - Add inline fnvHash64a() to avoid fnv.New64a() heap allocation - Update all 6 balancer algorithms (RoundRobin, WeightedRoundRobin, LeastConnections, IPHash, Random, ConsistentHash) to use pooled filterContext via acquire/release pattern - ConsistentHash.SelectExcludingByKey also uses pool for targetSet - Remove buildExcludeSet (merged into filterIntoExcluding) Result: allocs/op reduced from 2-3 to 0-1 on all LB Select paths.
81 lines
2.0 KiB
Go
81 lines
2.0 KiB
Go
// Package loadbalance 提供多种负载均衡算法实现，支持随机、轮询、加权、一致性哈希等策略。
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//
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// 包含随机负载均衡算法相关的逻辑。
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//
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// 作者：xfy
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package loadbalance
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import (
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"math/rand/v2"
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"sync/atomic"
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)
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// Random 实现随机负载均衡（Power of Two Choices 算法）。
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//
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// 随机选择两个候选目标，从中选择连接数较少的那个。
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// 相比纯随机，Power of Two Choices 能更好地均衡负载，
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// 同时保持 O(1) 的选择复杂度。
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//
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// 当只有一个候选目标时直接返回；当 MaxConns 限制生效时
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// 自动跳过已满的目标。
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type Random struct{}
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// NewRandom 创建一个新的随机负载均衡器。
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func NewRandom() *Random {
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return &Random{}
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}
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// Select 使用 Power of Two Choices 算法选择目标。
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// 随机选择两个候选，返回连接数较少的那个。
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// 只考虑可用目标。如果没有可用目标则返回 nil。
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func (r *Random) Select(targets []*Target) *Target {
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fc := acquireFilterContext()
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defer releaseFilterContext(fc)
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available := filterInto(fc, targets)
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if len(available) == 0 {
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return nil
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}
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if len(available) == 1 {
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return available[0]
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}
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i := rand.IntN(len(available))
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j := rand.IntN(len(available) - 1)
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if j >= i {
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j++
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}
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a, b := available[i], available[j]
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if atomic.LoadInt64(&a.Connections) <= atomic.LoadInt64(&b.Connections) {
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return a
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}
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return b
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}
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// SelectExcluding 使用 Power of Two Choices 算法选择目标，排除指定的目标列表。
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func (r *Random) SelectExcluding(targets []*Target, excluded []*Target) *Target {
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fc := acquireFilterContext()
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defer releaseFilterContext(fc)
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available := filterIntoExcluding(fc, targets, excluded)
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if len(available) == 0 {
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return nil
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}
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if len(available) == 1 {
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return available[0]
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}
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i := rand.IntN(len(available))
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j := rand.IntN(len(available) - 1)
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if j >= i {
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j++
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}
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a, b := available[i], available[j]
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if atomic.LoadInt64(&a.Connections) <= atomic.LoadInt64(&b.Connections) {
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return a
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}
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return b
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}
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