--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/gc/metaspace/G1AddMetaspaceDependency.java	Wed Apr 10 13:27:35 2013 +0200
@@ -0,0 +1,123 @@
+/*
+ * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test G1AddMetaspaceDependency
+ * @bug 8010196
+ * @summary Checks that we don't get locking problems when adding metaspace dependencies with the G1 update buffer monitor
+ * @run main/othervm -XX:+UseG1GC -XX:G1UpdateBufferSize=1 G1AddMetaspaceDependency
+ */
+
+import java.io.InputStream;
+
+public class G1AddMetaspaceDependency {
+
+  static byte[] getClassBytes(String name) {
+    byte[] b = null;
+    try (InputStream is = ClassLoader.getSystemResourceAsStream(name)) {
+      byte[] tmp = new byte[is.available()];
+      is.read(tmp);
+      b = tmp;
+    } finally {
+      if (b == null) {
+        throw new RuntimeException("Unable to load class file");
+      }
+      return b;
+    }
+  }
+
+  static final String a_name = G1AddMetaspaceDependency.class.getName() + "$A";
+  static final String b_name = G1AddMetaspaceDependency.class.getName() + "$B";
+
+  public static void main(String... args) throws Exception {
+    final byte[] a_bytes = getClassBytes(a_name + ".class");
+    final byte[] b_bytes = getClassBytes(b_name + ".class");
+
+    for (int i = 0; i < 1000; i += 1) {
+      runTest(a_bytes, b_bytes);
+    }
+  }
+
+  static class Loader extends ClassLoader {
+    private final String myClass;
+    private final byte[] myBytes;
+    private final String friendClass;
+    private final ClassLoader friendLoader;
+
+    Loader(String myClass, byte[] myBytes,
+           String friendClass, ClassLoader friendLoader) {
+      this.myClass = myClass;
+      this.myBytes = myBytes;
+      this.friendClass = friendClass;
+      this.friendLoader = friendLoader;
+    }
+
+    Loader(String myClass, byte[] myBytes) {
+      this(myClass, myBytes, null, null);
+    }
+
+    @Override
+    public Class<?> loadClass(String name) throws ClassNotFoundException {
+      Class<?> c = findLoadedClass(name);
+      if (c != null) {
+        return c;
+      }
+
+      if (name.equals(friendClass)) {
+        return friendLoader.loadClass(name);
+      }
+
+      if (name.equals(myClass)) {
+        c = defineClass(name, myBytes, 0, myBytes.length);
+        resolveClass(c);
+        return c;
+      }
+
+      return findSystemClass(name);
+    }
+
+  }
+
+  private static void runTest(final byte[] a_bytes, final byte[] b_bytes) throws Exception {
+    Loader a_loader = new Loader(a_name, a_bytes);
+    Loader b_loader = new Loader(b_name, b_bytes, a_name, a_loader);
+    Loader c_loader = new Loader(b_name, b_bytes, a_name, a_loader);
+    Loader d_loader = new Loader(b_name, b_bytes, a_name, a_loader);
+    Loader e_loader = new Loader(b_name, b_bytes, a_name, a_loader);
+    Loader f_loader = new Loader(b_name, b_bytes, a_name, a_loader);
+    Loader g_loader = new Loader(b_name, b_bytes, a_name, a_loader);
+
+    byte[] b = new byte[20 * 2 << 20];
+    Class<?> c;
+    c = b_loader.loadClass(b_name);
+    c = c_loader.loadClass(b_name);
+    c = d_loader.loadClass(b_name);
+    c = e_loader.loadClass(b_name);
+    c = f_loader.loadClass(b_name);
+    c = g_loader.loadClass(b_name);
+  }
+  public class A {
+  }
+  class B extends A {
+  }
+}