--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/hotspot/jtreg/serviceability/attach/AttachSetGetFlag.java	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,178 @@
+/*
+ * Copyright (c) 2014, 2017, 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
+ * @bug 8054823
+ * @summary Tests the setFlag and printFlag attach command
+ * @library /test/lib
+ * @modules java.base/jdk.internal.misc
+ *          java.compiler
+ *          java.management
+ *          jdk.attach/sun.tools.attach
+ *          jdk.internal.jvmstat/sun.jvmstat.monitor
+ * @run main AttachSetGetFlag
+ */
+
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+import java.io.InputStream;
+import java.lang.reflect.Field;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+
+import sun.tools.attach.HotSpotVirtualMachine;
+
+import jdk.test.lib.Asserts;
+import jdk.test.lib.Platform;
+import jdk.test.lib.process.ProcessTools;
+import com.sun.tools.attach.VirtualMachine;
+
+public class AttachSetGetFlag {
+
+  public static void main(String... args) throws Exception {
+    // Test a manageable uintx flag.
+    testGetFlag("MaxHeapFreeRatio", "60");
+    testSetFlag("MaxHeapFreeRatio", "50", "60");
+
+    // Test a non-manageable size_t flag.
+    // Since it is not manageable, we can't test the setFlag functionality.
+    testGetFlag("ArrayAllocatorMallocLimit", "128");
+    // testSetFlag("ArrayAllocatorMallocLimit", "64", "128");
+
+    // Test a uint flag.
+    testGetFlag("ParallelGCThreads", "10");
+  }
+
+  public static ProcessBuilder runTarget(String flagName, String flagValue) throws Exception {
+    return ProcessTools.createJavaProcessBuilder(
+        "-XX:+UnlockExperimentalVMOptions",
+        "-XX:" + flagName + "=" + flagValue,
+        "AttachSetGetFlag$Target");
+  }
+
+  public static void testGetFlag(String flagName, String flagValue) throws Exception {
+    ProcessBuilder pb = runTarget(flagName, flagValue);
+
+    Process target = pb.start();
+
+    try {
+      waitForReady(target);
+
+      int pid = (int)target.pid();
+
+      HotSpotVirtualMachine vm = (HotSpotVirtualMachine)VirtualMachine.attach(((Integer)pid).toString());
+
+      // Test Get
+      BufferedReader remoteDataReader = new BufferedReader(new InputStreamReader(
+          vm.printFlag(flagName)));
+
+      boolean foundExpectedLine = false;
+
+      String line = null;
+      while((line = remoteDataReader.readLine()) != null) {
+        System.out.println("printFlag: " + line);
+        if (line.equals("-XX:" + flagName + "=" + flagValue)) {
+          foundExpectedLine = true;
+        }
+      }
+
+      Asserts.assertTrue(foundExpectedLine, "Didn't get the expected output: '-XX:" + flagName + "=" + flagValue + "'");
+
+      vm.detach();
+    }
+    finally {
+      target.destroy();
+      target.waitFor();
+    }
+  }
+
+  public static void testSetFlag(String flagName, String initialFlagValue, String flagValue) throws Exception {
+    ProcessBuilder pb = runTarget(flagName, initialFlagValue);
+
+    Process target = pb.start();
+
+    try {
+      waitForReady(target);
+
+      int pid = (int)target.pid();
+
+      HotSpotVirtualMachine vm = (HotSpotVirtualMachine)VirtualMachine.attach(((Integer)pid).toString());
+
+      // First set the value.
+      BufferedReader remoteDataReader = new BufferedReader(new InputStreamReader(
+          vm.setFlag(flagName, flagValue)));
+
+      String line;
+      while((line = remoteDataReader.readLine()) != null) {
+        System.out.println("setFlag: " + line);
+        // Just empty the stream.
+      }
+      remoteDataReader.close();
+
+      // Then read and make sure we get back the set value.
+      remoteDataReader = new BufferedReader(new InputStreamReader(vm.printFlag(flagName)));
+
+      boolean foundExpectedLine = false;
+      line = null;
+      while((line = remoteDataReader.readLine()) != null) {
+        System.out.println("getFlag: " + line);
+        if (line.equals("-XX:" + flagName + "=" + flagValue)) {
+          foundExpectedLine = true;
+        }
+      }
+
+      Asserts.assertTrue(foundExpectedLine, "Didn't get the expected output: '-XX:" + flagName + "=" + flagValue + "'");
+
+      vm.detach();
+
+    } finally {
+      target.destroy();
+      target.waitFor();
+    }
+  }
+
+  private static void waitForReady(Process target) throws Exception {
+    InputStream os = target.getInputStream();
+    try (BufferedReader reader = new BufferedReader(new InputStreamReader(os))) {
+      String line;
+      while ((line = reader.readLine()) != null) {
+        if ("Ready".equals(line)) {
+          return;
+        }
+      }
+    }
+  }
+
+
+  public static class Target {
+    public static void main(String [] args) throws Exception {
+      System.out.println("Ready");
+      System.out.flush();
+      while (true) {
+        Thread.sleep(1000);
+      }
+    }
+  }
+}