--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/test/gc/g1/TestShrinkDefragmentedHeap.java Thu Sep 11 14:21:13 2014 +0200
@@ -0,0 +1,188 @@
+/*
+ * Copyright (c) 2014, 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 TestShrinkDefragmentedHeap
+ * @bug 8038423
+ * @summary Verify that heap shrinks after GC in the presence of fragmentation due to humongous objects
+ * 1. allocate small objects mixed with humongous ones
+ * "ssssHssssHssssHssssHssssHssssHssssH"
+ * 2. release all allocated object except the last humongous one
+ * "..................................H"
+ * 3. invoke gc and check that memory returned to the system (amount of committed memory got down)
+ *
+ * @library /testlibrary
+ */
+import java.lang.management.ManagementFactory;
+import java.lang.management.MemoryUsage;
+import java.util.ArrayList;
+import java.util.List;
+import sun.management.ManagementFactoryHelper;
+import static com.oracle.java.testlibrary.Asserts.*;
+import com.oracle.java.testlibrary.ProcessTools;
+import com.oracle.java.testlibrary.OutputAnalyzer;
+
+public class TestShrinkDefragmentedHeap {
+ // Since we store all the small objects, they become old and old regions are also allocated at the bottom of the heap
+ // together with humongous regions. So if there are a lot of old regions in the lower part of the heap,
+ // the humongous regions will be allocated in the upper part of the heap anyway.
+ // To avoid this the Eden needs to be big enough to fit all the small objects.
+ private static final int INITIAL_HEAP_SIZE = 200 * 1024 * 1024;
+ private static final int MINIMAL_YOUNG_SIZE = 190 * 1024 * 1024;
+ private static final int REGION_SIZE = 1 * 1024 * 1024;
+
+ public static void main(String[] args) throws Exception, Throwable {
+ ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(
+ "-XX:InitialHeapSize=" + INITIAL_HEAP_SIZE,
+ "-Xmn" + MINIMAL_YOUNG_SIZE,
+ "-XX:MinHeapFreeRatio=10",
+ "-XX:MaxHeapFreeRatio=11",
+ "-XX:+UseG1GC",
+ "-XX:G1HeapRegionSize=" + REGION_SIZE,
+ "-verbose:gc",
+ GCTest.class.getName()
+ );
+
+ OutputAnalyzer output = ProcessTools.executeProcess(pb);
+ output.shouldHaveExitValue(0);
+ }
+
+ static class GCTest {
+
+ private static final String MIN_FREE_RATIO_FLAG_NAME = "MinHeapFreeRatio";
+ private static final String MAX_FREE_RATIO_FLAG_NAME = "MaxHeapFreeRatio";
+ private static final String NEW_SIZE_FLAG_NAME = "NewSize";
+
+ private static final ArrayList<ArrayList<byte[]>> garbage = new ArrayList<>();
+
+ private static final int SMALL_OBJS_SIZE = 10 * 1024; // 10kB
+ private static final int SMALL_OBJS_COUNT = MINIMAL_YOUNG_SIZE / (SMALL_OBJS_SIZE-1);
+ private static final int ALLOCATE_COUNT = 3;
+ // try to put all humongous object into gap between min young size and initial heap size
+ // to avoid implicit GCs
+ private static final int HUMONG_OBJS_SIZE = (int) Math.max(
+ (INITIAL_HEAP_SIZE - MINIMAL_YOUNG_SIZE) / ALLOCATE_COUNT / 4,
+ REGION_SIZE * 1.1
+ );
+
+ private static final long initialHeapSize = getHeapMemoryUsage().getUsed();
+
+ public static void main(String[] args) throws InterruptedException {
+ new GCTest().test();
+ }
+
+ private void test() throws InterruptedException {
+ MemoryUsagePrinter.printMemoryUsage("init");
+
+ allocate();
+ System.gc();
+ MemoryUsage muFull = getHeapMemoryUsage();
+ MemoryUsagePrinter.printMemoryUsage("allocated");
+
+ free();
+ //Thread.sleep(1000); // sleep before measures due lags in JMX
+ MemoryUsage muFree = getHeapMemoryUsage();
+ MemoryUsagePrinter.printMemoryUsage("free");
+
+ assertLessThan(muFree.getCommitted(), muFull.getCommitted(), prepareMessageCommittedIsNotLess() );
+ }
+
+ private void allocate() {
+ System.out.format("Will allocate objects of small size = %s and humongous size = %s",
+ MemoryUsagePrinter.humanReadableByteCount(SMALL_OBJS_SIZE, false),
+ MemoryUsagePrinter.humanReadableByteCount(HUMONG_OBJS_SIZE, false)
+ );
+
+ for (int i = 0; i < ALLOCATE_COUNT; i++) {
+ ArrayList<byte[]> stuff = new ArrayList<>();
+ allocateList(stuff, SMALL_OBJS_COUNT / ALLOCATE_COUNT, SMALL_OBJS_SIZE);
+ garbage.add(stuff);
+
+ ArrayList<byte[]> humongousStuff = new ArrayList<>();
+ allocateList(humongousStuff, 4, HUMONG_OBJS_SIZE);
+ garbage.add(humongousStuff);
+ }
+ }
+
+ private void free() {
+ // do not free last one list
+ garbage.subList(0, garbage.size() - 1).clear();
+
+ // do not free last one element from last list
+ ArrayList stuff = garbage.get(garbage.size() - 1);
+ if (stuff.size() > 1) {
+ stuff.subList(0, stuff.size() - 1).clear();
+ }
+ System.gc();
+ }
+
+ private String prepareMessageCommittedIsNotLess() {
+ return 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,
+ ManagementFactoryHelper.getDiagnosticMXBean().getVMOption(MIN_FREE_RATIO_FLAG_NAME).getValue(),
+ MAX_FREE_RATIO_FLAG_NAME,
+ ManagementFactoryHelper.getDiagnosticMXBean().getVMOption(MAX_FREE_RATIO_FLAG_NAME).getValue()
+ );
+ }
+
+ private static void allocateList(List garbage, int count, int size) {
+ for (int i = 0; i < count; i++) {
+ garbage.add(new byte[size]);
+ }
+ }
+ }
+
+ static MemoryUsage getHeapMemoryUsage() {
+ return ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
+ }
+
+ /**
+ * Prints memory usage to standard output
+ */
+ static class MemoryUsagePrinter {
+
+ public static String humanReadableByteCount(long bytes, boolean si) {
+ int unit = si ? 1000 : 1024;
+ if (bytes < unit) {
+ return bytes + " B";
+ }
+ int exp = (int) (Math.log(bytes) / Math.log(unit));
+ String pre = (si ? "kMGTPE" : "KMGTPE").charAt(exp - 1) + (si ? "" : "i");
+ return String.format("%.1f %sB", bytes / Math.pow(unit, exp), pre);
+ }
+
+ public static void printMemoryUsage(String label) {
+ MemoryUsage memusage = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
+ float freeratio = 1f - (float) memusage.getUsed() / memusage.getCommitted();
+ System.out.format("[%-24s] init: %-7s, used: %-7s, comm: %-7s, freeRatio ~= %.1f%%%n",
+ label,
+ humanReadableByteCount(memusage.getInit(), false),
+ humanReadableByteCount(memusage.getUsed(), false),
+ humanReadableByteCount(memusage.getCommitted(), false),
+ freeratio * 100
+ );
+ }
+ }
+}