diff --git a/WHATSNEW b/WHATSNEW
index 7f4110d15..6e1e4dacd 100644
--- a/WHATSNEW
+++ b/WHATSNEW
@@ -7,9 +7,18 @@ Changes that could break older environments:
 Fixed bugs:
 -----------
 
+ * Tasks that iterate over task or type definitions, references or
+   targets now iterate over copies instead of the live maps to avoid
+   ConcurrentModificationExceptions if another thread changes the
+   maps.
+   Bugzilla Report 48310.
+
 Other changes:
 --------------
 
+ * Project provides new get methods that return copies instead of the
+   live maps of task and type definitions, references and targets.
+
 Changes from Ant 1.8.0RC1 TO Ant 1.8.0
 ======================================
 
diff --git a/src/main/org/apache/tools/ant/Project.java b/src/main/org/apache/tools/ant/Project.java
index 875352fa3..b2446f267 100644
--- a/src/main/org/apache/tools/ant/Project.java
+++ b/src/main/org/apache/tools/ant/Project.java
@@ -425,10 +425,10 @@ public class Project implements ResourceFactory {
     }
 
     /**
-         * Return a copy of the list of build listeners for the project.
-         * 
-         * @return a list of build listeners for the project
-         */
+     * Return a copy of the list of build listeners for the project.
+     * 
+     * @return a list of build listeners for the project
+     */
     public Vector getBuildListeners() {
         synchronized (listenersLock) {
             Vector r = new Vector(listeners.length);
@@ -1024,6 +1024,19 @@ public class Project implements ResourceFactory {
         return ComponentHelper.getComponentHelper(this).getTaskDefinitions();
     }
 
+    /**
+     * Return the current task definition map. The returned map is a
+     * copy of the "live" definitions.
+     *
+     * @return a map of from task name to implementing class
+     *         (String to Class).
+     *
+     * @since Ant 1.8.1
+     */
+    public Map getCopyOfTaskDefinitions() {
+        return new HashMap(getTaskDefinitions());
+    }
+
     /**
      * Add a new datatype definition.
      * Attempting to override an existing definition with an
@@ -1053,6 +1066,19 @@ public class Project implements ResourceFactory {
         return ComponentHelper.getComponentHelper(this).getDataTypeDefinitions();
     }
 
+    /**
+     * Return the current datatype definition map. The returned
+     * map is a copy pf the "live" definitions.
+     *
+     * @return a map of from datatype name to implementing class
+     *         (String to Class).
+     *
+     * @since Ant 1.8.1
+     */
+    public Map getCopyOfDataTypeDefinitions() {
+        return new HashMap(getDataTypeDefinitions());
+    }
+
     /**
      * Add a <em>new</em> target to the project.
      *
@@ -1123,6 +1149,16 @@ public class Project implements ResourceFactory {
         return targets;
     }
 
+    /**
+     * Return the map of targets. The returned map
+     * is a copy of the &quot;live&quot; targets.
+     * @return a map from name to target (String to Target).
+     * @since Ant 1.8.1
+     */
+    public Map getCopyOfTargets() {
+        return new HashMap(targets);
+    }
+
     /**
      * Create a new instance of a task, adding it to a list of
      * created tasks for later invalidation. This causes all tasks
@@ -1970,6 +2006,19 @@ public class Project implements ResourceFactory {
         return references.containsKey(key);
     }
 
+    /**
+     * Return a map of the references in the project (String to
+     * Object).  The returned hashtable is a copy of the
+     * &quot;live&quot; references.
+     *
+     * @return a map of the references in the project (String to Object).
+     *
+     * @since Ant 1.8.1
+     */
+    public Map getCopyOfReferences() {
+        return new HashMap(references);
+    }
+
     /**
      * Look up a reference by its key (ID).
      *
diff --git a/src/main/org/apache/tools/ant/taskdefs/AntStructure.java b/src/main/org/apache/tools/ant/taskdefs/AntStructure.java
index 5468305b0..475cc832f 100644
--- a/src/main/org/apache/tools/ant/taskdefs/AntStructure.java
+++ b/src/main/org/apache/tools/ant/taskdefs/AntStructure.java
@@ -27,6 +27,7 @@ import java.io.PrintWriter;
 import java.io.UnsupportedEncodingException;
 import java.util.Enumeration;
 import java.util.Hashtable;
+import java.util.Iterator;
 import java.util.Vector;
 import org.apache.tools.ant.BuildException;
 import org.apache.tools.ant.IntrospectionHelper;
@@ -95,22 +96,24 @@ public class AntStructure extends Task {
             }
 
             printer.printHead(out, getProject(),
-                              getProject().getTaskDefinitions(),
-                              getProject().getDataTypeDefinitions());
+                              new Hashtable(getProject().getTaskDefinitions()),
+                              new Hashtable(getProject().getDataTypeDefinitions()));
 
             printer.printTargetDecl(out);
 
-            Enumeration dataTypes = getProject().getDataTypeDefinitions().keys();
-            while (dataTypes.hasMoreElements()) {
-                String typeName = (String) dataTypes.nextElement();
+            Iterator dataTypes = getProject().getCopyOfDataTypeDefinitions()
+                .keySet().iterator();
+            while (dataTypes.hasNext()) {
+                String typeName = (String) dataTypes.next();
                 printer.printElementDecl(
                     out, getProject(), typeName,
                     (Class) getProject().getDataTypeDefinitions().get(typeName));
             }
 
-            Enumeration tasks = getProject().getTaskDefinitions().keys();
-            while (tasks.hasMoreElements()) {
-                String tName = (String) tasks.nextElement();
+            Iterator tasks = getProject().getCopyOfTaskDefinitions().keySet()
+                .iterator();
+            while (tasks.hasNext()) {
+                String tName = (String) tasks.next();
                 printer.printElementDecl(out, getProject(), tName,
                                          (Class) getProject().getTaskDefinitions().get(tName));
             }
diff --git a/src/main/org/apache/tools/ant/util/ScriptRunnerBase.java b/src/main/org/apache/tools/ant/util/ScriptRunnerBase.java
index 1bba545ae..b6f39248b 100644
--- a/src/main/org/apache/tools/ant/util/ScriptRunnerBase.java
+++ b/src/main/org/apache/tools/ant/util/ScriptRunnerBase.java
@@ -306,8 +306,8 @@ public abstract class ScriptRunnerBase {
         project = component.getProject();
         addBeans(project.getProperties());
         addBeans(project.getUserProperties());
-        addBeans(project.getTargets());
-        addBeans(project.getReferences());
+        addBeans(project.getCopyOfTargets());
+        addBeans(project.getCopyOfReferences());
         addBean("project", project);
         addBean("self", component);
     }