[GitHub] [dubbo] stonelion commented on a diff in pull request #10229: refactor: optimize ExtensionLoader code style

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

stonelion commented on code in PR #10229:
URL: https://github.com/apache/dubbo/pull/10229#discussion_r911582889


##########
dubbo-common/src/main/java/org/apache/dubbo/common/extension/ExtensionLoader.java:
##########
@@ -436,18 +425,7 @@ public T getExtension(String name, boolean wrap) {
         if ("true".equals(name)) {
             return getDefaultExtension();
         }
-        final Holder<Object> holder = getOrCreateHolder(name);
-        Object instance = holder.get();
-        if (instance == null) {
-            synchronized (holder) {
-                instance = holder.get();
-                if (instance == null) {
-                    instance = createExtension(name, wrap);
-                    holder.set(instance);
-                }
-            }
-        }
-        return (T) instance;
+        return cachedInstances.computeIfAbsent(name, (k) -> createExtension(k, wrap));

Review Comment:
   The method computeIfAbsent of ConcurrentHashMap is atomic. That function is applied at most once per key.



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