Index: web/web-core/src/main/java/org/apache/catalina/core/StandardContext.java
===================================================================
--- web/web-core/src/main/java/org/apache/catalina/core/StandardContext.java	(revision 55254)
+++ web/web-core/src/main/java/org/apache/catalina/core/StandardContext.java	(working copy)
@@ -104,6 +104,7 @@
 import java.security.PrivilegedAction;
 import java.util.*;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
@@ -211,7 +212,7 @@
      * The set of application parameters defined for this application.
      */
     private List<ApplicationParameter> applicationParameters =
-        new ArrayList<ApplicationParameter>();
+        new CopyOnWriteArrayList<ApplicationParameter>();
 
     /**
      * The application available flag for this Context.
Index: web/web-core/src/main/java/org/apache/catalina/core/ApplicationContext.java
===================================================================
--- web/web-core/src/main/java/org/apache/catalina/core/ApplicationContext.java	(revision 55254)
+++ web/web-core/src/main/java/org/apache/catalina/core/ApplicationContext.java	(working copy)
@@ -157,7 +157,7 @@
     /**
      * The merged context initialization parameters for this Context.
      */
-    private Map<String, String> parameters =
+    private ConcurrentHashMap<String, String> parameters =
         new ConcurrentHashMap<String, String>();
 
     private volatile boolean parametersMerged = false;
@@ -1026,16 +1026,14 @@
         }
         List<ApplicationParameter> params =
             context.findApplicationParameters();
-        synchronized(params) {
-            Iterator<ApplicationParameter> i = params.iterator(); 
-            while (i.hasNext()) {
-                ApplicationParameter param = i.next();
-                if (param.getOverride()) {
-                    if (parameters.get(param.getName()) == null)
-                        parameters.put(param.getName(), param.getValue());
-                } else {
-                    parameters.put(param.getName(), param.getValue());
-                }
+        Iterator<ApplicationParameter> i = params.iterator(); 
+        while (i.hasNext()) {
+            ApplicationParameter param = i.next();
+            if (param.getOverride()) {
+                if (parameters.get(param.getName()) == null)
+                    parameters.putIfAbsent(param.getName(), param.getValue());
+            } else {
+                parameters.put(param.getName(), param.getValue());
             }
         }
         parametersMerged = true;
Index: web/war-util/src/main/java/org/glassfish/web/loader/WebappClassLoader.java
===================================================================
--- web/war-util/src/main/java/org/glassfish/web/loader/WebappClassLoader.java	(revision 55254)
+++ web/war-util/src/main/java/org/glassfish/web/loader/WebappClassLoader.java	(working copy)
@@ -1533,7 +1533,9 @@
                     Permission p = perms.next();
                     pc.add(p);
                 }
-                loaderPC.put(codeUrl,pc);
+                PermissionCollection tmpPc = loaderPC.putIfAbsent(codeUrl,pc);
+                if(tmpPc != null)
+                    pc = tmpPc;
             }
         }
         return (pc);
Index: web/web-glue/src/main/java/com/sun/enterprise/web/logger/FileLoggerHandlerFactory.java
===================================================================
--- web/web-glue/src/main/java/com/sun/enterprise/web/logger/FileLoggerHandlerFactory.java	(revision 55254)
+++ web/web-glue/src/main/java/com/sun/enterprise/web/logger/FileLoggerHandlerFactory.java	(working copy)
@@ -65,20 +65,22 @@
     public void postConstruct() {
     }
 
-    public synchronized FileLoggerHandler getHandler(String logFile) {
+    public FileLoggerHandler getHandler(String logFile) {
         FileLoggerHandler handler = map.get(logFile);
         if (handler == null) {
             handler = new FileLoggerHandler(logFile);
             if (logFormatter != null) {
                 handler.setFormatter(logFormatter);
             }
-            map.put(logFile, handler);
+            FileLoggerHandler tmpHandler = map.putIfAbsent(logFile, handler);
+            if(tmpHandler != null)
+                handler = tmpHandler;
         }
 
         return handler;
     }
 
-    public synchronized void removeHandler(String logFile) {
+    public void removeHandler(String logFile) {
         map.remove(logFile);
     }
 }
Index: web/web-glue/src/main/java/com/sun/enterprise/web/ContextFacade.java
===================================================================
--- web/web-glue/src/main/java/com/sun/enterprise/web/ContextFacade.java	(revision 55254)
+++ web/web-glue/src/main/java/com/sun/enterprise/web/ContextFacade.java	(working copy)
@@ -313,7 +313,11 @@
             regis = (DynamicServletRegistrationImpl)
                     createDynamicServletRegistrationImpl((StandardWrapper) wrapper);
 
-            servletRegisMap.put(servletName, regis);
+            DynamicServletRegistrationImpl tmpRegis = 
+                    (DynamicServletRegistrationImpl)
+                            servletRegisMap.putIfAbsent(servletName, regis);
+            if(tmpRegis != null)
+                regis = tmpRegis;
             servlets.put(servletName, className);
         }