--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/hotspot/jtreg/gc/TestFullGCCount.java	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,97 @@
+/*
+ * Copyright (c) 2011, 2016, 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 TestFullGCCount.java
+ * @bug 7072527
+ * @summary CMS: JMM GC counters overcount in some cases
+ * @requires !(vm.gc.ConcMarkSweep & vm.opt.ExplicitGCInvokesConcurrent == true)
+ * @modules java.management
+ * @run main/othervm -Xlog:gc TestFullGCCount
+ */
+
+import java.lang.management.GarbageCollectorMXBean;
+import java.lang.management.ManagementFactory;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+
+/*
+ * Originally for a specific failure in CMS, this test now monitors all
+ * collectors for double-counting of collections.
+ */
+public class TestFullGCCount {
+
+    static List<GarbageCollectorMXBean> collectors = ManagementFactory.getGarbageCollectorMXBeans();
+
+    public static void main(String[] args) {
+        int iterations = 20;
+        boolean failed = false;
+        String errorMessage = "";
+        HashMap<String, List> counts = new HashMap<>();
+
+        // Prime the collection of count lists for all collectors.
+        for (int i = 0; i < collectors.size(); i++) {
+            GarbageCollectorMXBean collector = collectors.get(i);
+            counts.put(collector.getName(), new ArrayList<>(iterations));
+        }
+
+        // Perform some gc, record collector counts.
+        for (int i = 0; i < iterations; i++) {
+            System.gc();
+            addCollectionCount(counts, i);
+        }
+
+        // Check the increments:
+        //   Old gen collectors should increase by one,
+        //   New collectors may or may not increase.
+        //   Any increase >=2 is unexpected.
+        for (String collector : counts.keySet()) {
+            System.out.println("Checking: " + collector);
+
+            for (int i = 0; i < iterations - 1; i++) {
+                List<Long> theseCounts = counts.get(collector);
+                long a = theseCounts.get(i);
+                long b = theseCounts.get(i + 1);
+                if (b - a >= 2) {
+                    failed = true;
+                    errorMessage += "Collector '" + collector + "' has increment " + (b - a) +
+                                    " at iteration " + i + "\n";
+                }
+            }
+        }
+        if (failed) {
+            System.err.println(errorMessage);
+            throw new RuntimeException("FAILED: System.gc collections miscounted.");
+        }
+        System.out.println("Passed.");
+    }
+
+    private static void addCollectionCount(HashMap<String, List> counts, int iteration) {
+        for (int i = 0; i < collectors.size(); i++) {
+            GarbageCollectorMXBean collector = collectors.get(i);
+            List thisList = counts.get(collector.getName());
+            thisList.add(collector.getCollectionCount());
+        }
+    }
+}