diff --git a/jaxrs/providers/jaxb/src/main/java/org/jboss/resteasy/plugins/providers/jaxb/XmlJAXBContextFinder.java b/jaxrs/providers/jaxb/src/main/java/org/jboss/resteasy/plugins/providers/jaxb/XmlJAXBContextFinder.java
index 67699a4..3a62c34 100644
--- a/jaxrs/providers/jaxb/src/main/java/org/jboss/resteasy/plugins/providers/jaxb/XmlJAXBContextFinder.java
+++ b/jaxrs/providers/jaxb/src/main/java/org/jboss/resteasy/plugins/providers/jaxb/XmlJAXBContextFinder.java
@@ -66,7 +66,9 @@ public class XmlJAXBContextFinder extends AbstractJAXBContextFinder implements C
       if (ctx != null) return ctx;
 
       ctx = createContext(paraAnnotations, classes);
-      collectionCache.put(key, ctx);
+      JAXBContext tmpCtx = collectionCache.putIfAbsent(key, ctx);
+      if(tmpCtx != null)
+         ctx = tmpCtx;
 
       return ctx;
    }
@@ -79,7 +81,9 @@ public class XmlJAXBContextFinder extends AbstractJAXBContextFinder implements C
       if (ctx != null) return ctx;
 
       ctx = createXmlTypeContext(paraAnnotations, classes);
-      xmlTypeCollectionCache.put(key, ctx);
+      JAXBContext tmpCtx = xmlTypeCollectionCache.putIfAbsent(key, ctx);
+      if(tmpCtx != null)
+         ctx = tmpCtx;
 
       return ctx;
    }
diff --git a/jaxrs/providers/jaxb/src/test/java/org/jboss/resteasy/test/providers/jaxb/JAXBCache.java b/jaxrs/providers/jaxb/src/test/java/org/jboss/resteasy/test/providers/jaxb/JAXBCache.java
index c96f05b..5b80144 100644
--- a/jaxrs/providers/jaxb/src/test/java/org/jboss/resteasy/test/providers/jaxb/JAXBCache.java
+++ b/jaxrs/providers/jaxb/src/test/java/org/jboss/resteasy/test/providers/jaxb/JAXBCache.java
@@ -68,7 +68,9 @@ public final class JAXBCache
          {
             throw new ExceptionAdapter(e);
          }
-         contextCache.putIfAbsent(classes, context);
+         JAXBContext tmpContext = contextCache.putIfAbsent(classes, context);
+         if(tmpContext != null)
+            context = tmpContext;
       }
       logger.debug("Locating JAXBContext for package: {0}", classes);
       return context;
diff --git a/jaxrs/providers/jettison/src/main/java/org/jboss/resteasy/plugins/providers/jaxb/json/JsonJAXBContextFinder.java b/jaxrs/providers/jettison/src/main/java/org/jboss/resteasy/plugins/providers/jaxb/json/JsonJAXBContextFinder.java
index 23bc01e..b52fdc1 100644
--- a/jaxrs/providers/jettison/src/main/java/org/jboss/resteasy/plugins/providers/jaxb/json/JsonJAXBContextFinder.java
+++ b/jaxrs/providers/jettison/src/main/java/org/jboss/resteasy/plugins/providers/jaxb/json/JsonJAXBContextFinder.java
@@ -108,7 +108,9 @@ public class JsonJAXBContextFinder extends AbstractJAXBContextFinder implements
          JAXBContext ctx = badgerCollectionCache.get(key);
          if (ctx != null) return ctx;
          ctx = new BadgerContext(classes);
-         badgerCollectionCache.put(key, ctx);
+         JAXBContext tmpCtx = badgerCollectionCache.putIfAbsent(key, ctx);
+         if(tmpCtx != null)
+            ctx = tmpCtx;
          return ctx;
       }
       else
@@ -116,7 +118,9 @@ public class JsonJAXBContextFinder extends AbstractJAXBContextFinder implements
          JAXBContext ctx = mappedCollectionCache.get(key);
          if (ctx != null) return ctx;
          ctx = new JettisonMappedContext(mapped, classes);
-         mappedCollectionCache.put(key, ctx);
+         JAXBContext tmpCtx = mappedCollectionCache.putIfAbsent(key, ctx);
+         if(tmpCtx != null)
+            ctx = tmpCtx;
          return ctx;
       }
    }
@@ -146,7 +150,9 @@ public class JsonJAXBContextFinder extends AbstractJAXBContextFinder implements
             jaxb = new JettisonMappedContext(type);
          }
       }
-      cache.putIfAbsent(type, jaxb);
+      JAXBContext tmpJaxb = cache.putIfAbsent(type, jaxb);
+      if(tmpJaxb != null)
+         jaxb = tmpJaxb;
       return jaxb;
    }
 
diff --git a/jaxrs/providers/test-all-jaxb/src/test/java/org/jboss/resteasy/test/providers/jaxb/JAXBCache.java b/jaxrs/providers/test-all-jaxb/src/test/java/org/jboss/resteasy/test/providers/jaxb/JAXBCache.java
index 7eccee3..a9139dc 100644
--- a/jaxrs/providers/test-all-jaxb/src/test/java/org/jboss/resteasy/test/providers/jaxb/JAXBCache.java
+++ b/jaxrs/providers/test-all-jaxb/src/test/java/org/jboss/resteasy/test/providers/jaxb/JAXBCache.java
@@ -68,7 +68,9 @@ public final class JAXBCache
          {
             throw new ExceptionAdapter(e);
          }
-         contextCache.putIfAbsent(classes, context);
+         JAXBContext tmpContext = contextCache.putIfAbsent(classes, context);
+         if(tmpContext != null)
+            context = tmpContext;
       }
       logger.debug("Locating JAXBContext for package: {0}", classes);
       return context;
diff --git a/jaxrs/resteasy-cache/resteasy-cache-core/src/main/java/org/jboss/resteasy/plugins/cache/server/SimpleServerCache.java b/jaxrs/resteasy-cache/resteasy-cache-core/src/main/java/org/jboss/resteasy/plugins/cache/server/SimpleServerCache.java
index cc0a04c..208ac9d 100644
--- a/jaxrs/resteasy-cache/resteasy-cache-core/src/main/java/org/jboss/resteasy/plugins/cache/server/SimpleServerCache.java
+++ b/jaxrs/resteasy-cache/resteasy-cache-core/src/main/java/org/jboss/resteasy/plugins/cache/server/SimpleServerCache.java
@@ -60,7 +60,7 @@ public class SimpleServerCache implements ServerCache
    }
 
 
-   private Map<String, Map<MediaType, CacheEntry>> cache = new ConcurrentHashMap<String, Map<MediaType, CacheEntry>>();
+   private ConcurrentHashMap<String, Map<MediaType, CacheEntry>> cache = new ConcurrentHashMap<String, Map<MediaType, CacheEntry>>();
 
    public Entry get(String uri, MediaType accept)
    {
@@ -80,7 +80,9 @@ public class SimpleServerCache implements ServerCache
       if (entry == null)
       {
          entry = new ConcurrentHashMap<MediaType, CacheEntry>();
-         cache.put(uri, entry);
+         Map<MediaType, CacheEntry> tmpEntry = cache.putIfAbsent(uri, entry);
+         if(tmpEntry != null)
+            entry = tmpEntry;
       }
       entry.put(mediaType, cacheEntry);
       return cacheEntry;
diff --git a/jaxrs/resteasy-jaxrs/src/main/java/org/jboss/resteasy/core/ResourceLocator.java b/jaxrs/resteasy-jaxrs/src/main/java/org/jboss/resteasy/core/ResourceLocator.java
index 19d13ca..0546cb8 100644
--- a/jaxrs/resteasy-jaxrs/src/main/java/org/jboss/resteasy/core/ResourceLocator.java
+++ b/jaxrs/resteasy-jaxrs/src/main/java/org/jboss/resteasy/core/ResourceLocator.java
@@ -132,7 +132,9 @@ public class ResourceLocator implements ResourceInvoker
          }
          
          registry.addResourceFactory(null, null, target.getClass());//subResourceClass);
-         cachedSubresources.putIfAbsent(target.getClass(), registry);
+         Registry tmpRegistry = cachedSubresources.putIfAbsent(target.getClass(), registry);
+         if(tmpRegistry != null)
+            registry = tmpRegistry;
       }
       ResourceInvoker invoker = registry.getResourceInvoker(request);
       if (invoker == null)
diff --git a/jaxrs/resteasy-jaxrs/src/main/java/org/jboss/resteasy/plugins/server/embedded/SimpleSecurityDomain.java b/jaxrs/resteasy-jaxrs/src/main/java/org/jboss/resteasy/plugins/server/embedded/SimpleSecurityDomain.java
index 1d6109f..83cb227 100644
--- a/jaxrs/resteasy-jaxrs/src/main/java/org/jboss/resteasy/plugins/server/embedded/SimpleSecurityDomain.java
+++ b/jaxrs/resteasy-jaxrs/src/main/java/org/jboss/resteasy/plugins/server/embedded/SimpleSecurityDomain.java
@@ -23,8 +23,9 @@ public class SimpleSecurityDomain implements SecurityDomain
       if (users == null)
       {
          users = new CopyOnWriteArraySet<String>();
-         roles.putIfAbsent(role, users);
-         users = roles.get(role);
+         Set<String> tmpUsers = roles.putIfAbsent(role, users);
+         if(tmpUsers != null)
+            users = tmpUsers;
       }
       users.add(user);
    }
diff --git a/jaxrs/security/resteasy-oauth/src/main/java/org/jboss/resteasy/auth/oauth/OAuthMemoryProvider.java b/jaxrs/security/resteasy-oauth/src/main/java/org/jboss/resteasy/auth/oauth/OAuthMemoryProvider.java
index 0c65666..3cc7dd9 100644
--- a/jaxrs/security/resteasy-oauth/src/main/java/org/jboss/resteasy/auth/oauth/OAuthMemoryProvider.java
+++ b/jaxrs/security/resteasy-oauth/src/main/java/org/jboss/resteasy/auth/oauth/OAuthMemoryProvider.java
@@ -142,7 +142,10 @@ public class OAuthMemoryProvider implements OAuthProvider {
             return consumer;
         }
         consumer = new OAuthConsumer(consumerKey, "therealfrog", displayName, connectURI);
-        consumers.putIfAbsent(consumerKey, consumer);
+        OAuthConsumer tmpConsumer = consumers.putIfAbsent(consumerKey, consumer);
+        if(tmpConsumer != null)
+           consumer = tmpConsumer;
+        
         return consumer;
 	}