[struts] branch struts-2-5-x updated: [WW-5121] Fix: remove contention during Scope.SINGLETON injection

[yasserzamani]

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yasserzamani pushed a commit to branch struts-2-5-x
in repository https://gitbox.apache.org/repos/asf/struts.git


The following commit(s) were added to refs/heads/struts-2-5-x by this push:
     new ce8b75d  [WW-5121] Fix: remove contention during Scope.SINGLETON 
injection
     new 7e912a2  Merge pull request #479 from 
davoustp/contention-in-singleton-injection-2.5.x
ce8b75d is described below

commit ce8b75de58cca46dade40d76d5d421be5ff808ba
Author: Pascal Davoust <pascal.davo...@eptica.com>
AuthorDate: Mon Mar 22 09:40:02 2021 +0100

    [WW-5121] Fix: remove contention during Scope.SINGLETON injection
---
 core/src/main/java/com/opensymphony/xwork2/inject/Scope.java | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/core/src/main/java/com/opensymphony/xwork2/inject/Scope.java 
b/core/src/main/java/com/opensymphony/xwork2/inject/Scope.java
index 86592bb..3974d6c 100644
--- a/core/src/main/java/com/opensymphony/xwork2/inject/Scope.java
+++ b/core/src/main/java/com/opensymphony/xwork2/inject/Scope.java
@@ -44,15 +44,17 @@ public enum Scope {
         @Override
         <T> InternalFactory<? extends T> scopeFactory(Class<T> type, String 
name, final InternalFactory<? extends T> factory) {
             return new InternalFactory<T>() {
-                T instance;
+                volatile T instance;
 
                 public T create(InternalContext context) {
-                    synchronized (context.getContainer()) {
-                        if (instance == null) {
-                            instance = 
InitializableFactory.wrapIfNeeded(factory).create(context);
+                    if (instance == null) {
+                        synchronized (context.getContainer()) {
+                            if (instance == null) {
+                                instance = 
InitializableFactory.wrapIfNeeded(factory).create(context);
+                            }
                         }
-                        return instance;
                     }
+                    return instance;
                 }
 
                 @Override