Merge 960ff8bd39 into f1ffb55c9a

* Only check latencies once every 10 seconds with `routeByLatency`

`routeByLatency` currently checks latencies any time a server returns
a MOVED or READONLY reply. When a shard is down, the ClusterClient
chooses to issue the request to a random server, which returns a MOVED
reply. This causes a state refresh and a latency update on all servers.
This can lead to significant ping load to clusters with a large number
of clients.

This introduces logic to ping only once every 10 seconds, only
performing a latency update on a node during the `GC` function if the
latency was set later than 10 seconds ago.

Fixes https://github.com/redis/go-redis/issues/2782

* use UnixNano instead of Unix for better precision

---------

Co-authored-by: ofekshenawa <104765379+ofekshenawa@users.noreply.github.com>

extra/redisotel/metrics.go

@@ -83,9 +83,9 @@ func InstrumentMetrics(rdb redis.UniversalClient, opts ...MetricsOption) error {
 }
 
 func reportPoolStats(rdb *redis.Client, conf *config) error {
-	labels := conf.attrs
-	idleAttrs := append(labels, attribute.String("state", "idle"))
-	usedAttrs := append(labels, attribute.String("state", "used"))
+	poolAttrs := attribute.NewSet(conf.attrs...)
+	idleAttrs := attribute.NewSet(append(poolAttrs.ToSlice(), attribute.String("state", "idle"))...)
+	usedAttrs := attribute.NewSet(append(poolAttrs.ToSlice(), attribute.String("state", "used"))...)
 
 	idleMax, err := conf.meter.Int64ObservableUpDownCounter(
 		"db.client.connections.idle.max",
@@ -132,14 +132,14 @@ func reportPoolStats(rdb *redis.Client, conf *config) error {
 		func(ctx context.Context, o metric.Observer) error {
 			stats := rdb.PoolStats()
 
-			o.ObserveInt64(idleMax, int64(redisConf.MaxIdleConns), metric.WithAttributes(labels...))
-			o.ObserveInt64(idleMin, int64(redisConf.MinIdleConns), metric.WithAttributes(labels...))
-			o.ObserveInt64(connsMax, int64(redisConf.PoolSize), metric.WithAttributes(labels...))
+			o.ObserveInt64(idleMax, int64(redisConf.MaxIdleConns), metric.WithAttributeSet(poolAttrs))
+			o.ObserveInt64(idleMin, int64(redisConf.MinIdleConns), metric.WithAttributeSet(poolAttrs))
+			o.ObserveInt64(connsMax, int64(redisConf.PoolSize), metric.WithAttributeSet(poolAttrs))
 
-			o.ObserveInt64(usage, int64(stats.IdleConns), metric.WithAttributes(idleAttrs...))
-			o.ObserveInt64(usage, int64(stats.TotalConns-stats.IdleConns), metric.WithAttributes(usedAttrs...))
+			o.ObserveInt64(usage, int64(stats.IdleConns), metric.WithAttributeSet(idleAttrs))
+			o.ObserveInt64(usage, int64(stats.TotalConns-stats.IdleConns), metric.WithAttributeSet(usedAttrs))
 
-			o.ObserveInt64(timeouts, int64(stats.Timeouts), metric.WithAttributes(labels...))
+			o.ObserveInt64(timeouts, int64(stats.Timeouts), metric.WithAttributeSet(poolAttrs))
 			return nil
 		},
 		idleMax,

osscluster.go

@@ -21,6 +21,10 @@ import (
 	"github.com/redis/go-redis/v9/internal/rand"
 )
 
+const (
+	minLatencyMeasurementInterval = 10 * time.Second
+)
+
 var errClusterNoNodes = fmt.Errorf("redis: cluster has no nodes")
 
 // ClusterOptions are used to configure a cluster client and should be
@@ -316,6 +320,10 @@ type clusterNode struct {
 	latency    uint32 // atomic
 	generation uint32 // atomic
 	failing    uint32 // atomic
+
+	// last time the latency measurement was performed for the node, stored in nanoseconds
+	// from epoch
+	lastLatencyMeasurement int64 // atomic
 }
 
 func newClusterNode(clOpt *ClusterOptions, addr string) *clusterNode {
@@ -368,6 +376,7 @@ func (n *clusterNode) updateLatency() {
 		latency = float64(dur) / float64(successes)
 	}
 	atomic.StoreUint32(&n.latency, uint32(latency+0.5))
+	n.SetLastLatencyMeasurement(time.Now())
 }
 
 func (n *clusterNode) Latency() time.Duration {
@@ -397,6 +406,10 @@ func (n *clusterNode) Generation() uint32 {
 	return atomic.LoadUint32(&n.generation)
 }
 
+func (n *clusterNode) LastLatencyMeasurement() int64 {
+	return atomic.LoadInt64(&n.lastLatencyMeasurement)
+}
+
 func (n *clusterNode) SetGeneration(gen uint32) {
 	for {
 		v := atomic.LoadUint32(&n.generation)
@@ -406,6 +419,15 @@ func (n *clusterNode) SetGeneration(gen uint32) {
 	}
 }
 
+func (n *clusterNode) SetLastLatencyMeasurement(t time.Time) {
+	for {
+		v := atomic.LoadInt64(&n.lastLatencyMeasurement)
+		if t.UnixNano() < v || atomic.CompareAndSwapInt64(&n.lastLatencyMeasurement, v, t.UnixNano()) {
+			break
+		}
+	}
+}
+
 //------------------------------------------------------------------------------
 
 type clusterNodes struct {
@@ -493,10 +515,11 @@ func (c *clusterNodes) GC(generation uint32) {
 	c.mu.Lock()
 
 	c.activeAddrs = c.activeAddrs[:0]
+	now := time.Now()
 	for addr, node := range c.nodes {
 		if node.Generation() >= generation {
 			c.activeAddrs = append(c.activeAddrs, addr)
-			if c.opt.RouteByLatency {
+			if c.opt.RouteByLatency && node.LastLatencyMeasurement() < now.Add(-minLatencyMeasurementInterval).UnixNano() {
 				go node.updateLatency()
 			}
 			continue