--- a/hotspot/src/share/vm/runtime/arguments.cpp	Sat Apr 22 12:05:20 2017 +0200
+++ b/hotspot/src/share/vm/runtime/arguments.cpp	Wed Apr 26 22:34:54 2017 -0400
@@ -2305,8 +2305,6 @@
   if (FLAG_SET_CMDLINE(bool, UseParallelGC, true) != Flag::SUCCESS) {
     return JNI_EINVAL;
   }
-  FLAG_SET_DEFAULT(ParallelGCThreads,
-          Abstract_VM_Version::parallel_worker_threads());
 
   // Encourage steady state memory management
   if (FLAG_SET_CMDLINE(uintx, ThresholdTolerance, 100) != Flag::SUCCESS) {

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/test/gc/arguments/TestAggressiveHeap.java	Wed Apr 26 22:34:54 2017 -0400
@@ -0,0 +1,93 @@
+/*
+ * Copyright (c) 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 TestAggressiveHeap
+ * @key gc
+ * @bug 8179084
+ * @requires vm.gc.Parallel
+ * @summary Test argument processing for -XX:+AggressiveHeap.
+ * @library /test/lib
+ * @modules java.base java.management
+ * @run driver TestAggressiveHeap
+ */
+
+import java.lang.management.ManagementFactory;
+import javax.management.MBeanServer;
+import javax.management.ObjectName;
+
+import jdk.test.lib.process.OutputAnalyzer;
+import jdk.test.lib.process.ProcessTools;
+
+public class TestAggressiveHeap {
+
+    public static void main(String args[]) throws Exception {
+        if (canUseAggressiveHeapOption()) {
+            testFlag();
+        }
+    }
+
+    // Note: Not a normal boolean flag; -XX:-AggressiveHeap is invalid.
+    private static final String option = "-XX:+AggressiveHeap";
+
+    // Option requires at least 256M, else error during option processing.
+    private static final long minMemory = 256 * 1024 * 1024;
+
+    // bool UseParallelGC = true {product} {command line}
+    private static final String parallelGCPattern =
+        " *bool +UseParallelGC *= *true +\\{product\\} *\\{command line\\}";
+
+    private static void testFlag() throws Exception {
+        ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(
+            option, "-XX:+PrintFlagsFinal", "-version");
+
+        OutputAnalyzer output = new OutputAnalyzer(pb.start());
+
+        output.shouldHaveExitValue(0);
+
+        String value = output.firstMatch(parallelGCPattern);
+        if (value == null) {
+            throw new RuntimeException(
+                option + " didn't set UseParallelGC as if from command line");
+        }
+    }
+
+    private static boolean haveRequiredMemory() throws Exception {
+        MBeanServer server = ManagementFactory.getPlatformMBeanServer();
+        ObjectName os = new ObjectName("java.lang", "type", "OperatingSystem");
+        Object attr = server.getAttribute(os, "TotalPhysicalMemorySize");
+        String value = attr.toString();
+        long memory = Long.parseLong(value);
+        return memory >= minMemory;
+    }
+
+    private static boolean canUseAggressiveHeapOption() throws Exception {
+        if (!haveRequiredMemory()) {
+            System.out.println(
+                "Skipping test of " + option + " : insufficient memory");
+            return false;
+        }
+        return true;
+    }
+}
+