diff --git a/balancer/balancer.go b/balancer/balancer.go
index 3f96dc26..bc4faa90 100644
--- a/balancer/balancer.go
+++ b/balancer/balancer.go
@@ -1,6 +1,7 @@
 package balancer
 
 import (
+	"context"
 	"math"
 	"math/rand"
 	"sort"
@@ -18,7 +19,7 @@ var _ Balancer = (*rttBasedBalancer)(nil)
 // Balancer is interface for load balancers
 type Balancer interface {
 	// Pick picks a qualified nodes
-	Pick(network string) string
+	Pick(ctx context.Context, network string) string
 	// Networks returns the supported network types
 	Networks() []string
 }
@@ -27,6 +28,7 @@ type rttBasedBalancer struct {
 	nodes   []*Node
 	rttFunc rttFunc
 	options *option.BalancerOutboundOptions
+	logger  log.ContextLogger
 
 	*HealthCheck
 	costs *WeightManager
@@ -43,6 +45,7 @@ func newRTTBasedBalancer(
 	return &rttBasedBalancer{
 		rttFunc:     rttFunc,
 		options:     &options,
+		logger:      logger,
 		HealthCheck: NewHealthCheck(router, options.Outbounds, logger, &options.Check),
 		costs: NewWeightManager(
 			logger, options.Pick.Costs, 1,
@@ -94,7 +97,7 @@ func (s *rttBasedBalancer) Networks() []string {
 }
 
 // Select selects qualified nodes
-func (s *rttBasedBalancer) Pick(network string) string {
+func (s *rttBasedBalancer) Pick(ctx context.Context, network string) string {
 	nodes := s.HealthCheck.Nodes(network)
 	var candidates []*Node
 	if len(nodes.Qualified) > 0 {
@@ -113,8 +116,10 @@ func (s *rttBasedBalancer) Pick(network string) string {
 		return ""
 	}
 	picked := selects[rand.Intn(count)]
-	s.logger.Debug(
-		"pick [", picked.Tag, "]",
+	s.logger.DebugContext(
+		ctx,
+		"(network=", network, ", candidates=", count, ")",
+		" => [", picked.Tag, "]",
 		" +W=", picked.Weighted,
 		" STD=", picked.Deviation,
 		" AVG=", picked.Average,
diff --git a/outbound/balancer.go b/outbound/balancer.go
index 387e0b5f..0b753201 100644
--- a/outbound/balancer.go
+++ b/outbound/balancer.go
@@ -87,7 +87,7 @@ func (s *Balancer) Network() []string {
 
 // Now implements adapter.OutboundGroup
 func (s *Balancer) Now() string {
-	return s.pick("").Tag()
+	return s.pick(context.Background(), "").Tag()
 }
 
 // All implements adapter.OutboundGroup
@@ -97,22 +97,22 @@ func (s *Balancer) All() []string {
 
 // DialContext implements adapter.Outbound
 func (s *Balancer) DialContext(ctx context.Context, network string, destination M.Socksaddr) (net.Conn, error) {
-	return s.pick(network).DialContext(ctx, network, destination)
+	return s.pick(ctx, network).DialContext(ctx, network, destination)
 }
 
 // ListenPacket implements adapter.Outbound
 func (s *Balancer) ListenPacket(ctx context.Context, destination M.Socksaddr) (net.PacketConn, error) {
-	return s.pick(N.NetworkUDP).ListenPacket(ctx, destination)
+	return s.pick(ctx, N.NetworkUDP).ListenPacket(ctx, destination)
 }
 
 // NewConnection implements adapter.Outbound
 func (s *Balancer) NewConnection(ctx context.Context, conn net.Conn, metadata adapter.InboundContext) error {
-	return s.pick(N.NetworkTCP).NewConnection(ctx, conn, metadata)
+	return s.pick(ctx, N.NetworkTCP).NewConnection(ctx, conn, metadata)
 }
 
 // NewPacketConnection implements adapter.Outbound
 func (s *Balancer) NewPacketConnection(ctx context.Context, conn N.PacketConn, metadata adapter.InboundContext) error {
-	return s.pick(N.NetworkUDP).NewPacketConnection(ctx, conn, metadata)
+	return s.pick(ctx, N.NetworkUDP).NewPacketConnection(ctx, conn, metadata)
 }
 
 // Close implements io.Closer
@@ -149,24 +149,26 @@ func (s *Balancer) setBalancer(b balancer.Balancer) error {
 	return nil
 }
 
-func (s *Balancer) pick(network string) adapter.Outbound {
-	tag := s.pickTag(network)
+func (s *Balancer) pick(ctx context.Context, network string) adapter.Outbound {
+	tag := s.pickTag(ctx, network)
 	if tag == "" {
+		s.logger.DebugContext(ctx, "(network=", network, ", candidates=0) => fallback [", s.fallbackTag, "]")
 		return s.fallback
 	}
 	outbound, ok := s.router.Outbound(tag)
 	if !ok {
+		s.logger.DebugContext(ctx, "[", tag, "] not exist, fallback to [", s.fallbackTag, "]")
 		return s.fallback
 	}
 	return outbound
 }
 
-func (s *Balancer) pickTag(network string) string {
+func (s *Balancer) pickTag(ctx context.Context, network string) string {
 	if s.Balancer == nil {
 		// not started yet, pick a random one
 		return s.randomTag()
 	}
-	tag := s.Balancer.Pick(network)
+	tag := s.Balancer.Pick(ctx, network)
 	if tag == "" {
 		return ""
 	}