| /* |
| * 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, |
| "-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<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 |
| ); |
| } |
| } |
| } |