perf: Fanout for async updates in global (#198)

* perf: Fanout for async updates in global

* fix: data race

* use fanout

* make it configurable

* rename config

config.go

@@ -64,6 +64,9 @@ type BehaviorConfig struct {
 	GlobalBatchLimit int
 	// ForceGlobal forces global mode on all rate limit checks.
 	ForceGlobal bool
+
+	// Number of concurrent requests that will be made to peers. Defaults to 100
+	GlobalPeerRequestsConcurrency int
 }
 
 // Config for a gubernator instance
@@ -126,6 +129,8 @@ func (c *Config) SetDefaults() error {
 	setter.SetDefault(&c.Behaviors.GlobalBatchLimit, maxBatchSize)
 	setter.SetDefault(&c.Behaviors.GlobalSyncWait, time.Millisecond*100)
 
+	setter.SetDefault(&c.Behaviors.GlobalPeerRequestsConcurrency, 100)
+
 	setter.SetDefault(&c.LocalPicker, NewReplicatedConsistentHash(nil, defaultReplicas))
 	setter.SetDefault(&c.RegionPicker, NewRegionPicker(nil))
 

global.go

@@ -151,18 +151,23 @@ func (gm *globalManager) sendHits(hits map[string]*RateLimitReq) {
 		}
 	}
 
+	fan := syncutil.NewFanOut(gm.conf.GlobalPeerRequestsConcurrency)
 	// Send the rate limit requests to their respective owning peers.
 	for _, p := range peerRequests {
-		ctx, cancel := context.WithTimeout(context.Background(), gm.conf.GlobalTimeout)
-		_, err := p.client.GetPeerRateLimits(ctx, &p.req)
-		cancel()
-
-		if err != nil {
-			gm.log.WithError(err).
-				Errorf("error sending global hits to '%s'", p.client.Info().GRPCAddress)
-			continue
-		}
+		fan.Run(func(in interface{}) error {
+			p := in.(*pair)
+			ctx, cancel := context.WithTimeout(context.Background(), gm.conf.GlobalTimeout)
+			_, err := p.client.GetPeerRateLimits(ctx, &p.req)
+			cancel()
+
+			if err != nil {
+				gm.log.WithError(err).
+					Errorf("error sending global hits to '%s'", p.client.Info().GRPCAddress)
+			}
+			return nil
+		}, p)
 	}
+	fan.Wait()
 }
 
 // runBroadcasts collects status changes for global rate limits and broadcasts the changes to each peer in the cluster.
@@ -232,24 +237,29 @@ func (gm *globalManager) broadcastPeers(ctx context.Context, updates map[string]
 		})
 	}
 
+	fan := syncutil.NewFanOut(gm.conf.GlobalPeerRequestsConcurrency)
 	for _, peer := range gm.instance.GetPeerList() {
 		// Exclude ourselves from the update
 		if peer.Info().IsOwner {
 			continue
 		}
 
-		ctx, cancel := context.WithTimeout(ctx, gm.conf.GlobalTimeout)
-		_, err := peer.UpdatePeerGlobals(ctx, &req)
-		cancel()
-
-		if err != nil {
-			// Skip peers that are not in a ready state
-			if !IsNotReady(err) {
-				gm.log.WithError(err).Errorf("while broadcasting global updates to '%s'", peer.Info().GRPCAddress)
+		fan.Run(func(in interface{}) error {
+			peer := in.(*PeerClient)
+			ctx, cancel := context.WithTimeout(ctx, gm.conf.GlobalTimeout)
+			_, err := peer.UpdatePeerGlobals(ctx, &req)
+			cancel()
+
+			if err != nil {
+				// Skip peers that are not in a ready state
+				if !IsNotReady(err) {
+					gm.log.WithError(err).Errorf("while broadcasting global updates to '%s'", peer.Info().GRPCAddress)
+				}
 			}
-			continue
-		}
+			return nil
+		}, peer)
 	}
+	fan.Wait()
 }
 
 func (gm *globalManager) Close() {