Clear the previous  hashmap once new SS is downloaded.

listener.go

diff --git a/listener.go b/listener.go
index 9c002f2..f770dba 100644
--- a/listener.go
+++ b/listener.go
@@ -25,8 +25,15 @@
 )
 
 func processSnapshot(snapshot *common.Snapshot) {
-	log.Debugf("Snapshot received. Switching to DB version: %s", snapshot.SnapshotInfo)
 
+	if apidInfo.LastSnapshot != "" && apidInfo.LastSnapshot != snapshot.SnapshotInfo {
+		log.Debugf("Release snapshot for {%s}. Switching to version {%s}",
+			apidInfo.LastSnapshot , snapshot.SnapshotInfo)
+		dataService.ReleaseDB(apidInfo.LastSnapshot)
+	} else {
+		log.Debugf("Process snapshot for version {%s}",
+			snapshot.SnapshotInfo)
+	}
 	db, err := dataService.DBVersion(snapshot.SnapshotInfo)
 	if err != nil {
 		log.Panicf("Unable to access database: %v", err)