--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/hotspot/jtreg/gc/g1/TestPeriodicCollection.java	Mon Dec 10 10:25:27 2018 +0100
@@ -0,0 +1,110 @@
+/*
+ * Copyright (c) 2018, 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 TestPeriodicCollection
+ * @requires vm.gc.G1
+ * @requires vm.compMode != "Xcomp"
+ * @summary Verify that heap shrinks when the application is idle.
+ * @library /test/lib /
+ * @modules java.base/jdk.internal.misc
+ * @modules java.management/sun.management
+ * @run main/othervm -XX:MaxNewSize=32M -XX:InitialHeapSize=48M -Xmx128M -XX:MinHeapFreeRatio=5 -XX:MaxHeapFreeRatio=25 -XX:+UseG1GC -XX:G1PeriodicGCInterval=3000 -XX:+G1PeriodicGCInvokesConcurrent -Xlog:gc,gc+periodic=debug,gc+ergo+heap=debug TestPeriodicCollection
+ * @run main/othervm -XX:MaxNewSize=32M -XX:InitialHeapSize=48M -Xmx128M -XX:MinHeapFreeRatio=5 -XX:MaxHeapFreeRatio=25 -XX:+UseG1GC -XX:G1PeriodicGCInterval=3000 -XX:-G1PeriodicGCInvokesConcurrent -Xlog:gc,gc+periodic=debug,gc+ergo+heap=debug TestPeriodicCollection
+ */
+
+import com.sun.management.HotSpotDiagnosticMXBean;
+
+import gc.testlibrary.Helpers;
+
+import java.lang.management.GarbageCollectorMXBean;
+import java.lang.management.ManagementFactory;
+import java.lang.management.MemoryUsage;
+import java.text.NumberFormat;
+import static jdk.test.lib.Asserts.*;
+
+public class TestPeriodicCollection {
+
+    public static final String MIN_FREE_RATIO_FLAG_NAME = "MinHeapFreeRatio";
+    public static final String MAX_FREE_RATIO_FLAG_NAME = "MaxHeapFreeRatio";
+
+    private static final int IDLE_TIME = 7 * 1000;
+
+    private static boolean gcOccurred() {
+        for (GarbageCollectorMXBean b : ManagementFactory.getGarbageCollectorMXBeans()) {
+            if (b.getCollectionCount() != 0) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    public static void main(String[] args) {
+        MemoryUsage muInitial = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
+        MemoryUsagePrinter.printMemoryUsage("initial", muInitial);
+
+        if (gcOccurred()) {
+          System.out.println("At least one garbage collection occurred. Exiting as this may have already shrunk the heap.");
+          return;
+        }
+
+        try {
+            Thread.sleep(IDLE_TIME);
+        } catch (InterruptedException ie) {
+            System.err.println("Skipped. Failed to wait for idle collection");
+        }
+
+        MemoryUsage muAfter = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
+        MemoryUsagePrinter.printMemoryUsage("after", muAfter);
+
+        assertLessThan(muAfter.getCommitted(), muInitial.getCommitted(), String.format(
+                "committed free heap size is not less than committed full heap size, heap hasn't been shrunk?%n"
+                + "%s = %s%n%s = %s",
+                MIN_FREE_RATIO_FLAG_NAME,
+                ManagementFactory.getPlatformMXBean(HotSpotDiagnosticMXBean.class)
+                    .getVMOption(MIN_FREE_RATIO_FLAG_NAME).getValue(),
+                MAX_FREE_RATIO_FLAG_NAME,
+                ManagementFactory.getPlatformMXBean(HotSpotDiagnosticMXBean.class)
+                    .getVMOption(MAX_FREE_RATIO_FLAG_NAME).getValue()
+        ));
+    }
+}
+
+/**
+ * Prints memory usage to standard output
+ */
+class MemoryUsagePrinter {
+
+    public static final NumberFormat NF = Helpers.numberFormatter();
+
+    public static void printMemoryUsage(String label, MemoryUsage memusage) {
+        float freeratio = 1f - (float) memusage.getUsed() / memusage.getCommitted();
+        System.out.format("[%-24s] init: %-7s, used: %-7s, comm: %-7s, freeRatio ~= %.1f%%%n",
+                label,
+                NF.format(memusage.getInit()),
+                NF.format(memusage.getUsed()),
+                NF.format(memusage.getCommitted()),
+                freeratio * 100
+        );
+    }
+}