diff --git a/apm-collector/apm-collector-core/src/main/java/org/apache/skywalking/apm/collector/core/util/TimeBucketUtils.java b/apm-collector/apm-collector-core/src/main/java/org/apache/skywalking/apm/collector/core/util/TimeBucketUtils.java
index 8bb4366db..9597231b3 100644
--- a/apm-collector/apm-collector-core/src/main/java/org/apache/skywalking/apm/collector/core/util/TimeBucketUtils.java
+++ b/apm-collector/apm-collector-core/src/main/java/org/apache/skywalking/apm/collector/core/util/TimeBucketUtils.java
@@ -27,37 +27,35 @@ import java.util.Calendar;
 public enum TimeBucketUtils {
     INSTANCE;
 
-    public static final SimpleDateFormat MONTH_DATE_FORMAT = new SimpleDateFormat("yyyyMM");
-    public static final SimpleDateFormat DAY_DATE_FORMAT = new SimpleDateFormat("yyyyMMdd");
-    public static final SimpleDateFormat HOUR_DATE_FORMAT = new SimpleDateFormat("yyyyMMddHH");
-    public static final SimpleDateFormat MINUTE_DATE_FORMAT = new SimpleDateFormat("yyyyMMddHHmm");
-    public static final SimpleDateFormat SECOND_DATE_FORMAT = new SimpleDateFormat("yyyyMMddHHmmss");
-
     public long getMinuteTimeBucket(long time) {
+        SimpleDateFormat minuteDateFormat = new SimpleDateFormat("yyyyMMddHHmm");
         Calendar calendar = Calendar.getInstance();
         calendar.setTimeInMillis(time);
-        String timeStr = MINUTE_DATE_FORMAT.format(calendar.getTime());
+        String timeStr = minuteDateFormat.format(calendar.getTime());
         return Long.valueOf(timeStr);
     }
 
     public long getSecondTimeBucket(long time) {
+        SimpleDateFormat secondDateFormat = new SimpleDateFormat("yyyyMMddHHmmss");
         Calendar calendar = Calendar.getInstance();
         calendar.setTimeInMillis(time);
-        String timeStr = SECOND_DATE_FORMAT.format(calendar.getTime());
+        String timeStr = secondDateFormat.format(calendar.getTime());
         return Long.valueOf(timeStr);
     }
 
     public long getHourTimeBucket(long time) {
+        SimpleDateFormat hourDateFormat = new SimpleDateFormat("yyyyMMddHH");
         Calendar calendar = Calendar.getInstance();
         calendar.setTimeInMillis(time);
-        String timeStr = HOUR_DATE_FORMAT.format(calendar.getTime()) + "00";
+        String timeStr = hourDateFormat.format(calendar.getTime()) + "00";
         return Long.valueOf(timeStr);
     }
 
     public long getDayTimeBucket(long time) {
+        SimpleDateFormat dayDateFormat = new SimpleDateFormat("yyyyMMdd");
         Calendar calendar = Calendar.getInstance();
         calendar.setTimeInMillis(time);
-        String timeStr = DAY_DATE_FORMAT.format(calendar.getTime()) + "0000";
+        String timeStr = dayDateFormat.format(calendar.getTime()) + "0000";
         return Long.valueOf(timeStr);
     }
 
diff --git a/docker-compose.yml b/docker-compose.yml
index 09db04f8e..aeb1328f7 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -1,7 +1,7 @@
 version: '2.1'
 services:
   skywalking-webui:
-    image: skywalking/skywalking-ui:5.0-2018-preview
+    image: skywalking/skywalking-ui:5.0.0-alpha
     expose:
       - "8080"
     ports:
@@ -15,7 +15,7 @@ services:
       - COLLECTOR_SERVERS=skywalking-collector:10800
 
   skywalking-collector:
-    image: skywalking/skywalking-collector:5.0-2018-preview
+    image: skywalking/skywalking-collector:5.0.0-alpha
     expose:
       - "10800"
       - "11800"