/* * Copyright (c) 2014, 2015, 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 8129590 * @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 /test/lib * @modules java.base/jdk.internal.misc * java.management/sun.management */ import java.lang.management.ManagementFactory; import java.lang.management.MemoryUsage; import java.util.ArrayList; import java.util.List; import static jdk.test.lib.Asserts.*; import jdk.test.lib.process.OutputAnalyzer; import jdk.test.lib.process.ProcessTools; import com.sun.management.HotSpotDiagnosticMXBean; 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 MAXIMUM_HEAP_SIZE = 256 * 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, "-Xmx" + MAXIMUM_HEAP_SIZE, "-XX:MinHeapFreeRatio=10", "-XX:MaxHeapFreeRatio=11", "-XX:+UseG1GC", "-XX:G1HeapRegionSize=" + REGION_SIZE, "-XX:-ExplicitGCInvokesConcurrent", "-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> 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 stuff = new ArrayList<>(); allocateList(stuff, SMALL_OBJS_COUNT / ALLOCATE_COUNT, SMALL_OBJS_SIZE); garbage.add(stuff); ArrayList 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, 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() ); } 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 ); } } }