[GitHub] [skywalking] kezhenxu94 commented on a change in pull request #2930: One more time for heigher performance

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kezhenxu94 commented on a change in pull request #2930: One more time for heigher performance
URL: https://github.com/apache/skywalking/pull/2930#discussion_r296446407
 
 

 ##########
 File path: apm-commons/apm-datacarrier/src/main/java/org/apache/skywalking/apm/commons/datacarrier/common/AtomicRangeInteger.java
 ##########
 @@ -18,23 +18,32 @@
 
 
 package org.apache.skywalking.apm.commons.datacarrier.common;
-
 import java.io.Serializable;
 import java.util.concurrent.atomic.AtomicInteger;
 
 /**
- * Created by wusheng on 2016/10/25.
+ * Created by lkxiaolou on 2019/06/22.
  */
 public class AtomicRangeInteger extends Number implements Serializable {
     private static final long serialVersionUID = -4099792402691141643L;
+
+    /**
+     * please dont't change the left and right Placeholders
+     * to disable false-sharing for more performance
+     */
+    private int[] leftPlaceholders;
     private AtomicInteger value;
+    private int[] rightPlaceholders;
+
     private int startValue;
     private int endValue;
 
     public AtomicRangeInteger(int startValue, int maxValue) {
         this.value = new AtomicInteger(startValue);
         this.startValue = startValue;
         this.endValue = maxValue - 1;
+        leftPlaceholders = new int[15];
+        rightPlaceholders = new int[15];
 
 Review comment:
   > I don't find the place to use `leftPlaceholders` and `rightPlaceholders`. And why the length is 15?
   
   It's indeed not used in the code because it's only declared to pad the cache line (64 bytes per line ), 15 * 4 = 60,  plus the value to occupy the entire cache line to dismiss the false-sharing, am I right ? @lkxiaolou but why do we need padding right? Did I miss anything ?

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