diff --git a/pkg/bbgo/session.go b/pkg/bbgo/session.go
index 7457f9a0c..e305adef5 100644
--- a/pkg/bbgo/session.go
+++ b/pkg/bbgo/session.go
@@ -422,7 +422,6 @@ func (session *ExchangeSession) initSymbol(ctx context.Context, environ *Environ
 
 	// always subscribe the 1m kline so we can make sure the connection persists.
 	klineSubscriptions[minInterval] = struct{}{}
-	log.Warnf("sub: %v", klineSubscriptions)
 
 	for interval := range klineSubscriptions {
 		// avoid querying the last unclosed kline
@@ -451,8 +450,6 @@ func (session *ExchangeSession) initSymbol(ctx context.Context, environ *Environ
 				session.lastPrices[symbol] = lastKLine.Close
 			}
 
-			log.Warnf("load %s", interval)
-
 			for _, k := range kLines {
 				// let market data store trigger the update, so that the indicator could be updated too.
 				marketDataStore.AddKLine(k)
diff --git a/pkg/types/interval.go b/pkg/types/interval.go
index 300ca0865..10c0243af 100644
--- a/pkg/types/interval.go
+++ b/pkg/types/interval.go
@@ -25,7 +25,8 @@ func (i Interval) Seconds() int {
 	return m
 }
 
-// specially handled, for better precision
+// Milliseconds is specially handled, for better precision
+// for ms level interval, calling Seconds and Minutes directly might trigger panic error
 func (i Interval) Milliseconds() int {
 	t := 0
 	index := 0