113 lines
4.1 KiB
Java
113 lines
4.1 KiB
Java
/*
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* Copyright (c) 2018, 2019, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*
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*/
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import java.lang.instrument.ClassFileTransformer;
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import java.lang.instrument.Instrumentation;
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import java.lang.instrument.IllegalClassFormatException;
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import java.security.ProtectionDomain;
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// This test is sensitive to -Xmx. It must be run with -xmx64m.
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// Running with a different -Xmx requires changing the parameters and careful re-testing.
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public class HumongousDuringDumpTransformer implements ClassFileTransformer {
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public byte[] transform(ClassLoader loader, String name, Class<?> classBeingRedefined,
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ProtectionDomain pd, byte[] buffer) throws IllegalClassFormatException {
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if (name.equals("Hello")) {
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try {
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makeHumongousRegions();
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} catch (Throwable t) {
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array = null;
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humon = null;
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System.out.println("Unexpected error: " + t);
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t.printStackTrace();
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}
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}
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array = null;
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return null;
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}
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private static Instrumentation savedInstrumentation;
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public static void premain(String agentArguments, Instrumentation instrumentation) {
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long xmx = Runtime.getRuntime().maxMemory();
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if (xmx < 60 * 1024 * 1024 || xmx > 80 * 1024 * 1024) {
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System.out.println("Running with incorrect heap size: " + xmx);
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System.exit(1);
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}
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System.out.println("ClassFileTransformer.premain() is called");
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instrumentation.addTransformer(new HumongousDuringDumpTransformer(), /*canRetransform=*/true);
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savedInstrumentation = instrumentation;
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}
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public static Instrumentation getInstrumentation() {
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return savedInstrumentation;
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}
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public static void agentmain(String args, Instrumentation inst) throws Exception {
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premain(args, inst);
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}
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Object[] array;
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static final int DUMMY_SIZE = 4096 - 16 - 8;
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static final int HUMON_SIZE = 4 * 1024 * 1024 - 16 - 8;
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static final int SKIP = 13;
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byte humon[] = null;
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boolean first = true;
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public synchronized void makeHumongousRegions() {
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if (!first) {
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return;
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}
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System.out.println("===============================================================================");
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first = false;
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int total = 0;
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array = new Object[100000];
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System.out.println(array);
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// (1) Allocate about 8MB of old objects.
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for (int n=0, i=0; total < 8 * 1024 * 1024; n++) {
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// Make enough allocations to cause a GC (for 64MB heap) to create
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// old regions.
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//
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// But don't completely fill up the heap. That would cause OOM and
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// may not be handled gracefully inside class transformation!
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Object x = new byte[DUMMY_SIZE];
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if ((n % SKIP) == 0) {
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array[i++] = x;
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total += DUMMY_SIZE;
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}
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}
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System.gc();
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// (2) Now allocate a humongous array. It will sit above the 8MB of old regions.
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humon = new byte[HUMON_SIZE];
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array = null;
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System.gc();
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}
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}
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