1 /* 2 * Copyright (c) 2014 Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 package org.openjdk.bench.vm.compiler; 26 27 import org.openjdk.jmh.annotations.Benchmark; 28 import org.openjdk.jmh.annotations.BenchmarkMode; 29 import org.openjdk.jmh.annotations.Mode; 30 import org.openjdk.jmh.annotations.OutputTimeUnit; 31 import org.openjdk.jmh.annotations.Param; 32 import org.openjdk.jmh.annotations.Scope; 33 import org.openjdk.jmh.annotations.State; 34 import org.openjdk.jmh.infra.Blackhole; 35 36 import java.util.Enumeration; 37 import java.util.Hashtable; 38 import java.util.concurrent.TimeUnit; 39 40 /** 41 * Tests that the JVM performs object explosion (or some sort of stack allocation). 42 */ 43 @BenchmarkMode(Mode.AverageTime) 44 @OutputTimeUnit(TimeUnit.NANOSECONDS) 45 @State(Scope.Thread) 46 public class Explosion { 47 48 @Param("5") 49 private int len; 50 51 @Benchmark 52 public void testHashtableExplosion(Blackhole bh) throws Exception { 53 Object o = new Object(); 54 Object[] oa = new Object[len]; 55 for (int i = 0; i < len; i++) { 56 oa[i] = new Object(); 57 } 58 59 Hashtable<Object, Object> h = new Hashtable<>(); 60 61 for (int i = 0; i < len; i++) { 62 h.put(oa[i], o); 63 } 64 65 Enumeration<Object> e = h.elements(); 66 while (e.hasMoreElements()) { 67 bh.consume(e.nextElement()); 68 } 69 } 70 }