[GitHub] [rocketmq] mxsm commented on a diff in pull request #5008: [ISSUE #4999]Optimize ConcurrentMap#computeIfAbsent performance on jdk1.8 a workaround

[GitBox <gi...@apache.org>]

mxsm commented on code in PR #5008:
URL: https://github.com/apache/rocketmq/pull/5008#discussion_r964337674


##########
common/src/main/java/org/apache/rocketmq/common/utils/ConcurrentHashMapUtils.java:
##########
@@ -39,10 +37,11 @@ private ConcurrentHashMapUtil() {
      */
     public static <K, V> V computeIfAbsent(ConcurrentMap<K, V> map, K key, Function<? super K, ? extends V> func) {
         if (IS_JDK8) {
-            V v, newValue;
-            return ((v = map.get(key)) == null &&
-                (newValue = func.apply(key)) != null &&
-                (v = map.putIfAbsent(key, newValue)) == null) ? newValue : v;
+            V v = map.get(key);
+            if (null == v) {
+                v = map.computeIfAbsent(key, func);
+            }
+            return v;

Review Comment:
   > Could you also provide JMH test results for this change?
   Ok I will 
   



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