diff --git a/build.xml b/build.xml
index 5957194..2511f75 100644
--- a/build.xml
+++ b/build.xml
@@ -399,7 +399,7 @@
     </java>
   </target>
 
-  <target name="group_writer" depends="build" description="Run group writer">
+  <target name="groups_writer" depends="build" description="Run groups writer">
     <java classpath="${build-src.dir}" fork="true"
       classname="${adaptor.pkg.name}.examples.GroupDefinitionsWriter">
       <classpath refid="adaptorlib.run.classpath"/>
@@ -432,6 +432,23 @@
     </java>
   </target>
 
+  <target name="groups_scale_tester" depends="build"
+      description="Run groups scale tester">
+    <java classpath="${build-src.dir}" fork="true"
+      classname="${adaptor.pkg.name}.examples.GroupDefinitionsScaleTester">
+      <classpath refid="adaptorlib.run.classpath"/>
+      <sysproperty key="java.util.logging.config.file"
+        value="${src.dir}/logging.properties"/>
+      <sysproperty key="javax.net.ssl.keyStore" file="keys.jks"/>
+      <sysproperty key="javax.net.ssl.keyStoreType" value="jks"/>
+      <sysproperty key="javax.net.ssl.keyStorePassword" value="changeit"/>
+      <sysproperty key="javax.net.ssl.trustStore" file="cacerts.jks"/>
+      <sysproperty key="javax.net.ssl.trustStoreType" value="jks"/>
+      <sysproperty key="javax.net.ssl.trustStorePassword" value="changeit"/>
+      <arg line="${adaptor.args}"/>
+    </java>
+  </target>
+
   <target name="sim" depends="build" description="run simulator">
     <java classpath="${build-src.dir}" fork="true"
         classname="com.google.enterprise.adaptor.experimental.Sim">
diff --git a/src/com/google/enterprise/adaptor/examples/GroupDefinitionsScaleTester.java b/src/com/google/enterprise/adaptor/examples/GroupDefinitionsScaleTester.java
new file mode 100644
index 0000000..fc93502
--- /dev/null
+++ b/src/com/google/enterprise/adaptor/examples/GroupDefinitionsScaleTester.java
@@ -0,0 +1,115 @@
+// Copyright 2014 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.enterprise.adaptor.examples;
+
+import com.google.enterprise.adaptor.AbstractAdaptor;
+import com.google.enterprise.adaptor.AdaptorContext;
+import com.google.enterprise.adaptor.Config;
+import com.google.enterprise.adaptor.DocIdPusher;
+import com.google.enterprise.adaptor.GroupPrincipal;
+import com.google.enterprise.adaptor.Principal;
+import com.google.enterprise.adaptor.Request;
+import com.google.enterprise.adaptor.Response;
+import com.google.enterprise.adaptor.UserPrincipal;
+
+import java.io.IOException;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import java.util.Random;
+import java.util.TreeMap;
+
+/** Creates groups and users and pushes some number of principals per group. */
+public class GroupDefinitionsScaleTester extends AbstractAdaptor {
+  private static final Logger log
+      = Logger.getLogger(GroupDefinitionsScaleTester.class.getName());
+
+  private int nusers;
+  private int ngroups;
+  private int nuserspergroup;
+  private int ngroupspergroup;
+
+  private String namespace;
+  private String domain;
+
+  private Random rander = new Random();
+
+  @Override
+  public void initConfig(Config config) {
+    config.addKey("test.numusers", null);
+    config.addKey("test.numgroups", null);
+    config.addKey("test.userspergroup", null);
+    config.addKey("test.grouppergroup", null);
+    config.addKey("test.namespace", "duper-draper-scarlet-and-bond");
+    config.addKey("test.domain", "duperduperdomain.net");
+  }
+
+  private static int toInt(String s) {
+    return Integer.parseInt(s);
+  }
+
+  @Override
+  public void init(AdaptorContext context) throws Exception {
+    nusers = toInt(context.getConfig().getValue("test.numusers"));
+    ngroups = toInt(context.getConfig().getValue("test.numgroups"));
+    nuserspergroup = toInt(context.getConfig().getValue("test.userspergroup"));
+    ngroupspergroup = toInt(context.getConfig().getValue("test.grouppergroup"));
+    namespace = context.getConfig().getValue("test.namespace");
+    domain = context.getConfig().getValue("test.domain");
+  }
+
+  private UserPrincipal makeUser(int i) {
+    return new UserPrincipal("user" + i + "@" + domain, namespace);
+  }
+
+  private GroupPrincipal makeGroup(int i) {
+    return new GroupPrincipal("group" + i + "@" + domain, namespace);
+  }
+
+  @Override
+  public void getDocIds(DocIdPusher pusher) throws InterruptedException,
+      IOException {
+    for (int i = 0; i < ngroups; i++) {
+      List<Principal> members = new ArrayList<Principal>();
+      for (int j = 0; j < ngroupspergroup; j++) {
+        int chosen = rander.nextInt(ngroups);
+        members.add(makeGroup(chosen));
+      }
+      for (int j = 0; j < nuserspergroup; j++) {
+        int chosen = rander.nextInt(nusers);
+        members.add(makeUser(chosen));
+      }
+      GroupPrincipal group = makeGroup(i);
+      Map<GroupPrincipal, List<Principal>> groupdef
+          = Collections.singletonMap(group, members);
+      final boolean caseSensitive = false;
+      pusher.pushGroupDefinitions(groupdef, caseSensitive);
+      log.log(Level.INFO, "pushed group {0} with {1} members", new Object[] {
+          group, members.size()});
+    }  
+  }
+
+  @Override
+  public void getDocContent(Request req, Response res) throws IOException {
+    res.respondNotFound();
+  }
+ 
+  public static void main(String args[]) {
+    AbstractAdaptor.main(new GroupDefinitionsScaleTester(), args);
+  }
+}