1 /*
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3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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13  * accompanied this code).
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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
testHashtableExplosion(Blackhole bh)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 }
69