diff --git a/dubbo-metrics/dubbo-metrics-api/src/main/java/org/apache/dubbo/metrics/aggregate/DubboMergingDigest.java b/dubbo-metrics/dubbo-metrics-api/src/main/java/org/apache/dubbo/metrics/aggregate/DubboMergingDigest.java
index 24bdfe1c74..b4bfe34b74 100644
--- a/dubbo-metrics/dubbo-metrics-api/src/main/java/org/apache/dubbo/metrics/aggregate/DubboMergingDigest.java
+++ b/dubbo-metrics/dubbo-metrics-api/src/main/java/org/apache/dubbo/metrics/aggregate/DubboMergingDigest.java
@@ -18,11 +18,12 @@
 package org.apache.dubbo.metrics.aggregate;
 
 
+import org.apache.dubbo.metrics.exception.MetricsNeverHappenException;
+
 import com.tdunning.math.stats.Centroid;
 import com.tdunning.math.stats.ScaleFunction;
 import com.tdunning.math.stats.Sort;
 import com.tdunning.math.stats.TDigest;
-import org.apache.dubbo.metrics.exception.MetricsNeverHappenException;
 
 import java.nio.ByteBuffer;
 import java.util.AbstractCollection;
@@ -285,16 +286,17 @@ public class DubboMergingDigest extends DubboAbstractTDigest {
             throw new IllegalArgumentException("Cannot add NaN to t-digest");
         }
 
+        int where;
         synchronized (this) {
             // There is a small probability of entering here
             if (tempUsed.get() >= tempWeight.length - lastUsedCell.get() - 1) {
                 mergeNewValues();
             }
+            where = tempUsed.getAndIncrement();
+            tempWeight[where] = w;
+            tempMean[where] = x;
+            unmergedWeight.addAndGet(w);
         }
-        int where = tempUsed.getAndIncrement();
-        tempWeight[where] = w;
-        tempMean[where] = x;
-        unmergedWeight.addAndGet(w);
         if (x < min) {
             min = x;
         }
diff --git a/dubbo-metrics/dubbo-metrics-api/src/test/java/org/apache/dubbo/metrics/aggregate/TimeWindowQuantileTest.java b/dubbo-metrics/dubbo-metrics-api/src/test/java/org/apache/dubbo/metrics/aggregate/TimeWindowQuantileTest.java
index 4d2aa21baa..170efd61f9 100644
--- a/dubbo-metrics/dubbo-metrics-api/src/test/java/org/apache/dubbo/metrics/aggregate/TimeWindowQuantileTest.java
+++ b/dubbo-metrics/dubbo-metrics-api/src/test/java/org/apache/dubbo/metrics/aggregate/TimeWindowQuantileTest.java
@@ -18,6 +18,7 @@
 package org.apache.dubbo.metrics.aggregate;
 
 import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.RepeatedTest;
 import org.junit.jupiter.api.Test;
 
 import java.util.concurrent.ExecutorService;
@@ -37,6 +38,7 @@ class TimeWindowQuantileTest {
     }
 
     @Test
+    @RepeatedTest(100)
     void testMulti() {
 
         ExecutorService executorService = Executors.newFixedThreadPool(200);
@@ -51,12 +53,14 @@ class TimeWindowQuantileTest {
                     quantile.add(finalI));
             }
             index++;
-            try {
-                Thread.sleep(100);
-            } catch (InterruptedException e) {
-                e.printStackTrace();
-            }
+//            try {
+//                Thread.sleep(1);
+//            } catch (InterruptedException e) {
+//                e.printStackTrace();
+//            }
         }
+
+        executorService.shutdown();
     }
 
 }