diff --git a/config/config.go b/config/config.go
index 76b03b425..6ed4c8957 100644
--- a/config/config.go
+++ b/config/config.go
@@ -16,6 +16,7 @@ package config
 
 import (
 	"github.com/BurntSushi/toml"
+	"sync"
 )
 
 const (
@@ -134,6 +135,17 @@ type RecommendConfig struct {
 	EnableItemBasedRecommend     bool               `toml:"enable_item_based_recommend"`
 	EnableColRecommend           bool               `toml:"enable_collaborative_recommend"`
 	EnableClickThroughPrediction bool               `toml:"enable_click_through_prediction"`
+	exploreRecommendLock         sync.Mutex
+}
+
+func (config *RecommendConfig) GetExploreRecommend(key string) (value float64, exist bool) {
+	if config == nil {
+		return 0.0, false
+	}
+	config.exploreRecommendLock.Lock()
+	defer config.exploreRecommendLock.Unlock()
+	value, exist = config.ExploreRecommend[key]
+	return
 }
 
 // LoadDefaultIfNil loads default settings if config is nil.
@@ -155,6 +167,7 @@ func (config *RecommendConfig) LoadDefaultIfNil() *RecommendConfig {
 			EnableItemBasedRecommend:     false,
 			EnableColRecommend:           true,
 			EnableClickThroughPrediction: false,
+			exploreRecommendLock:         sync.Mutex{},
 		}
 	}
 	return config
@@ -282,6 +295,7 @@ func (config *Config) FillDefault(meta toml.MetaData) {
 	if !meta.IsDefined("recommend", "enable_click_through_prediction") {
 		config.Recommend.EnableClickThroughPrediction = defaultRecommendConfig.EnableClickThroughPrediction
 	}
+	config.Recommend.exploreRecommendLock = sync.Mutex{}
 }
 
 // LoadConfig loads configuration from toml file.
diff --git a/config/config_test.go b/config/config_test.go
index c7216ae80..0f5147028 100644
--- a/config/config_test.go
+++ b/config/config_test.go
@@ -56,6 +56,14 @@ func TestLoadConfig(t *testing.T) {
 	assert.Equal(t, 1, config.Recommend.RefreshRecommendPeriod)
 	assert.Equal(t, []string{"item_based", "latest"}, config.Recommend.FallbackRecommend)
 	assert.Equal(t, map[string]float64{"popular": 0.1, "latest": 0.2}, config.Recommend.ExploreRecommend)
+	value, exist := config.Recommend.GetExploreRecommend("popular")
+	assert.Equal(t, true, exist)
+	assert.Equal(t, 0.1, value)
+	value, exist = config.Recommend.GetExploreRecommend("latest")
+	assert.Equal(t, true, exist)
+	assert.Equal(t, 0.2, value)
+	_, exist = config.Recommend.GetExploreRecommend("unknown")
+	assert.Equal(t, false, exist)
 	assert.Equal(t, "similar", config.Recommend.ItemNeighborType)
 	assert.Equal(t, "similar", config.Recommend.UserNeighborType)
 	assert.True(t, config.Recommend.EnableColRecommend)
@@ -67,9 +75,9 @@ func TestLoadConfig(t *testing.T) {
 }
 
 func TestConfig_FillDefault(t *testing.T) {
-	var config Config
+	var config *Config
 	meta, err := toml.Decode("", &config)
 	assert.NoError(t, err)
 	config.FillDefault(meta)
-	assert.Equal(t, *(*Config)(nil).LoadDefaultIfNil(), config)
+	assert.Equal(t, (*Config)(nil).LoadDefaultIfNil(), config)
 }
diff --git a/worker/worker.go b/worker/worker.go
index d7a50d9f2..b63899d07 100644
--- a/worker/worker.go
+++ b/worker/worker.go
@@ -713,11 +713,11 @@ func (w *Worker) exploreRecommend(exploitRecommend []cache.Scored, excludeSet *s
 	localExcludeSet := excludeSet.Copy()
 	// create thresholds
 	explorePopularThreshold := 0.0
-	if threshold, exist := w.cfg.Recommend.ExploreRecommend["popular"]; exist {
+	if threshold, exist := w.cfg.Recommend.GetExploreRecommend("popular"); exist {
 		explorePopularThreshold = threshold
 	}
 	exploreLatestThreshold := explorePopularThreshold
-	if threshold, exist := w.cfg.Recommend.ExploreRecommend["latest"]; exist {
+	if threshold, exist := w.cfg.Recommend.GetExploreRecommend("latest"); exist {
 		exploreLatestThreshold += threshold
 	}
 	// load popular items