fix: Remove watching config event in rate limiter (#32313)

Remove watching config event in rate limiter to prevent object leaks.
Instead, reset limiter rates periodically.

issue: https://github.com/milvus-io/milvus/issues/32312

---------

Signed-off-by: bigsheeper <yihao.dai@zilliz.com>

internal/proxy/simple_rate_limiter.go

@@ -30,7 +30,6 @@ import (
 	"github.com/milvus-io/milvus/internal/proto/proxypb"
 	"github.com/milvus-io/milvus/internal/util/quota"
 	rlinternal "github.com/milvus-io/milvus/internal/util/ratelimitutil"
-	"github.com/milvus-io/milvus/pkg/config"
 	"github.com/milvus-io/milvus/pkg/log"
 	"github.com/milvus-io/milvus/pkg/metrics"
 	"github.com/milvus-io/milvus/pkg/util/paramtable"
@@ -168,6 +167,28 @@ func (m *SimpleLimiter) GetQuotaStates() ([]milvuspb.QuotaState, []string) {
 func (m *SimpleLimiter) SetRates(rootLimiter *proxypb.LimiterNode) error {
 	m.quotaStatesMu.Lock()
 	defer m.quotaStatesMu.Unlock()
+
+	// Reset the limiter rates due to potential changes in configurations.
+	var (
+		clusterConfigs    = getDefaultLimiterConfig(internalpb.RateScope_Cluster)
+		databaseConfigs   = getDefaultLimiterConfig(internalpb.RateScope_Database)
+		collectionConfigs = getDefaultLimiterConfig(internalpb.RateScope_Collection)
+		partitionConfigs  = getDefaultLimiterConfig(internalpb.RateScope_Partition)
+	)
+	initLimiter(m.rateLimiter.GetRootLimiters(), clusterConfigs)
+	m.rateLimiter.GetRootLimiters().GetChildren().Range(func(_ int64, dbLimiter *rlinternal.RateLimiterNode) bool {
+		initLimiter(dbLimiter, databaseConfigs)
+		dbLimiter.GetChildren().Range(func(_ int64, collLimiter *rlinternal.RateLimiterNode) bool {
+			initLimiter(collLimiter, collectionConfigs)
+			collLimiter.GetChildren().Range(func(_ int64, partitionLimiter *rlinternal.RateLimiterNode) bool {
+				initLimiter(partitionLimiter, partitionConfigs)
+				return true
+			})
+			return true
+		})
+		return true
+	})
+
 	if err := m.updateRateLimiter(rootLimiter); err != nil {
 		return err
 	}
@@ -182,26 +203,6 @@ func initLimiter(rln *rlinternal.RateLimiterNode, rateLimiterConfigs map[interna
 		limit := ratelimitutil.Limit(p.GetAsFloat())
 		burst := p.GetAsFloat() // use rate as burst, because SimpleLimiter is with punishment mechanism, burst is insignificant.
 		rln.GetLimiters().GetOrInsert(rt, ratelimitutil.NewLimiter(limit, burst))
-		onEvent := func(rateType internalpb.RateType, formatFunc func(originValue string) string) func(*config.Event) {
-			return func(event *config.Event) {
-				f, err := strconv.ParseFloat(formatFunc(event.Value), 64)
-				if err != nil {
-					log.Info("Error format for rateLimit",
-						zap.String("rateType", rateType.String()),
-						zap.String("key", event.Key),
-						zap.String("value", event.Value),
-						zap.Error(err))
-					return
-				}
-				l, ok := rln.GetLimiters().Get(rateType)
-				if !ok {
-					log.Info("rateLimiter not found for rateType", zap.String("rateType", rateType.String()))
-					return
-				}
-				l.SetLimit(ratelimitutil.Limit(f))
-			}
-		}(rt, p.Formatter)
-		paramtable.Get().Watch(p.Key, config.NewHandler(fmt.Sprintf("rateLimiter-%d", rt), onEvent))
 		log.RatedDebug(30, "RateLimiter register for rateType",
 			zap.String("rateType", internalpb.RateType_name[(int32(rt))]),
 			zap.String("rateLimit", ratelimitutil.Limit(p.GetAsFloat()).String()),
@@ -235,8 +236,8 @@ func newCollectionLimiters() *rlinternal.RateLimiterNode {
 
 func newPartitionLimiters() *rlinternal.RateLimiterNode {
 	partRateLimiters := rlinternal.NewRateLimiterNode(internalpb.RateScope_Partition)
-	collectionLimiterConfigs := getDefaultLimiterConfig(internalpb.RateScope_Partition)
+	partitionLimiterConfigs := getDefaultLimiterConfig(internalpb.RateScope_Partition)
-	initLimiter(partRateLimiters, collectionLimiterConfigs)
+	initLimiter(partRateLimiters, partitionLimiterConfigs)
 	return partRateLimiters
 }