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