17764
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1 /*
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2 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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20 * or visit www.oracle.com if you need additional information or have any
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21 * questions.
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22 */
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23
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24 /*
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25 * Common code for string deduplication tests
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26 */
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27
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28 import java.lang.management.*;
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29 import java.lang.reflect.*;
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30 import java.security.*;
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31 import java.util.*;
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32 import com.oracle.java.testlibrary.*;
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33 import sun.misc.*;
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34
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35 class TestStringDeduplicationTools {
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36 private static final String YoungGC = "YoungGC";
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37 private static final String FullGC = "FullGC";
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38
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39 private static final int Xmn = 50; // MB
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40 private static final int Xms = 100; // MB
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41 private static final int Xmx = 100; // MB
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42 private static final int MB = 1024 * 1024;
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43 private static final int StringLength = 50;
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44
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45 private static Field valueField;
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46 private static Unsafe unsafe;
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47 private static byte[] dummy;
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48
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49 static {
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50 try {
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51 Field field = Unsafe.class.getDeclaredField("theUnsafe");
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52 field.setAccessible(true);
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53 unsafe = (Unsafe)field.get(null);
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54
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55 valueField = String.class.getDeclaredField("value");
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56 valueField.setAccessible(true);
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57 } catch (Exception e) {
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58 throw new RuntimeException(e);
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59 }
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60 }
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61
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62 private static Object getValue(String string) {
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63 try {
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64 return valueField.get(string);
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65 } catch (Exception e) {
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66 throw new RuntimeException(e);
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67 }
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68 }
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69
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70 private static void doFullGc(int numberOfTimes) {
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71 for (int i = 0; i < numberOfTimes; i++) {
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72 System.out.println("Begin: Full GC " + (i + 1) + "/" + numberOfTimes);
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73 System.gc();
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74 System.out.println("End: Full GC " + (i + 1) + "/" + numberOfTimes);
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75 }
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76 }
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77
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78 private static void doYoungGc(int numberOfTimes) {
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79 // Provoke at least numberOfTimes young GCs
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80 final int objectSize = 128;
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81 final int maxObjectInYoung = (Xmn * MB) / objectSize;
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82 for (int i = 0; i < numberOfTimes; i++) {
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83 System.out.println("Begin: Young GC " + (i + 1) + "/" + numberOfTimes);
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84 for (int j = 0; j < maxObjectInYoung + 1; j++) {
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85 dummy = new byte[objectSize];
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86 }
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87 System.out.println("End: Young GC " + (i + 1) + "/" + numberOfTimes);
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88 }
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89 }
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90
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91 private static void forceDeduplication(int ageThreshold, String gcType) {
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92 // Force deduplication to happen by either causing a FullGC or a YoungGC.
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93 // We do several collections to also provoke a situation where the the
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94 // deduplication thread needs to yield while processing the queue. This
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95 // also tests that the references in the deduplication queue are adjusted
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96 // accordingly.
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97 if (gcType.equals(FullGC)) {
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98 doFullGc(3);
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99 } else {
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100 doYoungGc(ageThreshold + 3);
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101 }
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102 }
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103
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104 private static String generateString(int id) {
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105 StringBuilder builder = new StringBuilder(StringLength);
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106
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107 builder.append("DeduplicationTestString:" + id + ":");
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108
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109 while (builder.length() < StringLength) {
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110 builder.append('X');
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111 }
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112
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113 return builder.toString();
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114 }
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115
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116 private static ArrayList<String> createStrings(int total, int unique) {
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117 System.out.println("Creating strings: total=" + total + ", unique=" + unique);
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118 if (total % unique != 0) {
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119 throw new RuntimeException("Total must be divisible by unique");
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120 }
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121
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122 ArrayList<String> list = new ArrayList<String>(total);
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123 for (int j = 0; j < total / unique; j++) {
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124 for (int i = 0; i < unique; i++) {
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125 list.add(generateString(i));
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126 }
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127 }
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128
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129 return list;
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130 }
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131
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132 private static void verifyStrings(ArrayList<String> list, int uniqueExpected) {
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133 for (;;) {
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134 // Check number of deduplicated strings
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135 ArrayList<Object> unique = new ArrayList<Object>(uniqueExpected);
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136 for (String string: list) {
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137 Object value = getValue(string);
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138 boolean uniqueValue = true;
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139 for (Object obj: unique) {
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140 if (obj == value) {
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141 uniqueValue = false;
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142 break;
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143 }
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144 }
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145
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146 if (uniqueValue) {
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147 unique.add(value);
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148 }
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149 }
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150
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151 System.out.println("Verifying strings: total=" + list.size() +
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152 ", uniqueFound=" + unique.size() +
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153 ", uniqueExpected=" + uniqueExpected);
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154
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155 if (unique.size() == uniqueExpected) {
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156 System.out.println("Deduplication completed");
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157 break;
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158 } else {
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159 System.out.println("Deduplication not completed, waiting...");
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160
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161 // Give the deduplication thread time to complete
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162 try {
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163 Thread.sleep(1000);
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164 } catch (Exception e) {
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165 throw new RuntimeException(e);
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166 }
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167 }
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168 }
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169 }
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170
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171 private static OutputAnalyzer runTest(String... extraArgs) throws Exception {
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172 String[] defaultArgs = new String[] {
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173 "-Xmn" + Xmn + "m",
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174 "-Xms" + Xms + "m",
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175 "-Xmx" + Xmx + "m",
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176 "-XX:+UseG1GC",
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177 "-XX:+UnlockDiagnosticVMOptions",
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178 "-XX:+VerifyAfterGC" // Always verify after GC
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179 };
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180
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181 ArrayList<String> args = new ArrayList<String>();
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182 args.addAll(Arrays.asList(defaultArgs));
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183 args.addAll(Arrays.asList(extraArgs));
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184
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185 ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(args.toArray(new String[args.size()]));
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186 OutputAnalyzer output = new OutputAnalyzer(pb.start());
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187 System.err.println(output.getStderr());
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188 System.out.println(output.getStdout());
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189 return output;
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190 }
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191
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192 private static class DeduplicationTest {
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193 public static void main(String[] args) {
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194 System.out.println("Begin: DeduplicationTest");
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195
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196 final int numberOfStrings = Integer.parseUnsignedInt(args[0]);
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197 final int numberOfUniqueStrings = Integer.parseUnsignedInt(args[1]);
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198 final int ageThreshold = Integer.parseUnsignedInt(args[2]);
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199 final String gcType = args[3];
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200
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201 ArrayList<String> list = createStrings(numberOfStrings, numberOfUniqueStrings);
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202 forceDeduplication(ageThreshold, gcType);
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203 verifyStrings(list, numberOfUniqueStrings);
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204
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205 System.out.println("End: DeduplicationTest");
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206 }
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207
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208 public static OutputAnalyzer run(int numberOfStrings, int ageThreshold, String gcType, String... extraArgs) throws Exception {
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209 String[] defaultArgs = new String[] {
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210 "-XX:+UseStringDeduplication",
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211 "-XX:StringDeduplicationAgeThreshold=" + ageThreshold,
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212 DeduplicationTest.class.getName(),
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213 "" + numberOfStrings,
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214 "" + numberOfStrings / 2,
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215 "" + ageThreshold,
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216 gcType
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217 };
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218
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219 ArrayList<String> args = new ArrayList<String>();
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220 args.addAll(Arrays.asList(extraArgs));
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221 args.addAll(Arrays.asList(defaultArgs));
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222
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223 return runTest(args.toArray(new String[args.size()]));
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224 }
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225 }
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226
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227 private static class InternedTest {
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228 public static void main(String[] args) {
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229 // This test verifies that interned strings are always
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230 // deduplicated when being interned, and never after
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231 // being interned.
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232
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233 System.out.println("Begin: InternedTest");
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234
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235 final int ageThreshold = Integer.parseUnsignedInt(args[0]);
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236 final String baseString = "DeduplicationTestString:" + InternedTest.class.getName();
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237
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238 // Create duplicate of baseString
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239 StringBuilder sb1 = new StringBuilder(baseString);
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240 String dupString1 = sb1.toString();
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241 if (getValue(dupString1) == getValue(baseString)) {
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242 throw new RuntimeException("Values should not match");
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243 }
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244
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245 // Force baseString to be inspected for deduplication
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246 // and be inserted into the deduplication hashtable.
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247 forceDeduplication(ageThreshold, FullGC);
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248
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249 // Wait for deduplication to occur
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250 while (getValue(dupString1) != getValue(baseString)) {
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251 System.out.println("Waiting...");
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252 try {
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253 Thread.sleep(100);
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254 } catch (Exception e) {
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255 throw new RuntimeException(e);
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256 }
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257 }
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258
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259 // Create a new duplicate of baseString
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260 StringBuilder sb2 = new StringBuilder(baseString);
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261 String dupString2 = sb2.toString();
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262 if (getValue(dupString2) == getValue(baseString)) {
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263 throw new RuntimeException("Values should not match");
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264 }
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265
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266 // Intern the new duplicate
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267 Object beforeInternedValue = getValue(dupString2);
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268 String internedString = dupString2.intern();
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269 if (internedString != dupString2) {
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270 throw new RuntimeException("String should match");
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271 }
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272 if (getValue(internedString) != getValue(baseString)) {
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273 throw new RuntimeException("Values should match");
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274 }
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275
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276 // Check original value of interned string, to make sure
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277 // deduplication happened on the interned string and not
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278 // on the base string
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279 if (beforeInternedValue == getValue(baseString)) {
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280 throw new RuntimeException("Values should not match");
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281 }
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282
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283 System.out.println("End: InternedTest");
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284 }
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285
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286 public static OutputAnalyzer run() throws Exception {
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287 return runTest("-XX:+PrintGC",
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288 "-XX:+PrintGCDetails",
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289 "-XX:+UseStringDeduplication",
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290 "-XX:+PrintStringDeduplicationStatistics",
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291 "-XX:StringDeduplicationAgeThreshold=" + DefaultAgeThreshold,
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292 InternedTest.class.getName(),
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293 "" + DefaultAgeThreshold);
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294 }
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295 }
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296
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297 private static class MemoryUsageTest {
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298 public static void main(String[] args) {
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299 System.out.println("Begin: MemoryUsageTest");
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300
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301 final boolean useStringDeduplication = Boolean.parseBoolean(args[0]);
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302 final int numberOfStrings = LargeNumberOfStrings;
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303 final int numberOfUniqueStrings = 1;
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304
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305 ArrayList<String> list = createStrings(numberOfStrings, numberOfUniqueStrings);
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306 forceDeduplication(DefaultAgeThreshold, FullGC);
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307
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308 if (useStringDeduplication) {
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309 verifyStrings(list, numberOfUniqueStrings);
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310 }
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311
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312 System.gc();
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313 System.out.println("Heap Memory Usage: " + ManagementFactory.getMemoryMXBean().getHeapMemoryUsage().getUsed());
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314
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315 System.out.println("End: MemoryUsageTest");
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316 }
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317
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318 public static OutputAnalyzer run(boolean useStringDeduplication) throws Exception {
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319 String[] extraArgs = new String[0];
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320
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321 if (useStringDeduplication) {
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322 extraArgs = new String[] {
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323 "-XX:+UseStringDeduplication",
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324 "-XX:+PrintStringDeduplicationStatistics",
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325 "-XX:StringDeduplicationAgeThreshold=" + DefaultAgeThreshold
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326 };
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327 }
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328
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329 String[] defaultArgs = new String[] {
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330 "-XX:+PrintGC",
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331 "-XX:+PrintGCDetails",
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332 MemoryUsageTest.class.getName(),
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333 "" + useStringDeduplication
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334 };
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335
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336 ArrayList<String> args = new ArrayList<String>();
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337 args.addAll(Arrays.asList(extraArgs));
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338 args.addAll(Arrays.asList(defaultArgs));
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339
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340 return runTest(args.toArray(new String[args.size()]));
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341 }
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342 }
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343
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344 /*
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345 * Tests
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346 */
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347
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348 private static final int LargeNumberOfStrings = 10000;
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349 private static final int SmallNumberOfStrings = 10;
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350
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351 private static final int MaxAgeThreshold = 15;
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352 private static final int DefaultAgeThreshold = 3;
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353 private static final int MinAgeThreshold = 1;
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354
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355 private static final int TooLowAgeThreshold = MinAgeThreshold - 1;
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356 private static final int TooHighAgeThreshold = MaxAgeThreshold + 1;
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357
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358 public static void testYoungGC() throws Exception {
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359 // Do young GC to age strings to provoke deduplication
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360 OutputAnalyzer output = DeduplicationTest.run(LargeNumberOfStrings,
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361 DefaultAgeThreshold,
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362 YoungGC,
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363 "-XX:+PrintGC",
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364 "-XX:+PrintStringDeduplicationStatistics");
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365 output.shouldNotContain("Full GC");
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366 output.shouldContain("GC pause (G1 Evacuation Pause) (young)");
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367 output.shouldContain("GC concurrent-string-deduplication");
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368 output.shouldContain("Deduplicated:");
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369 output.shouldHaveExitValue(0);
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370 }
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371
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372 public static void testFullGC() throws Exception {
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373 // Do full GC to age strings to provoke deduplication
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374 OutputAnalyzer output = DeduplicationTest.run(LargeNumberOfStrings,
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375 DefaultAgeThreshold,
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376 FullGC,
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377 "-XX:+PrintGC",
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378 "-XX:+PrintStringDeduplicationStatistics");
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379 output.shouldNotContain("GC pause (G1 Evacuation Pause) (young)");
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380 output.shouldContain("Full GC");
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381 output.shouldContain("GC concurrent-string-deduplication");
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382 output.shouldContain("Deduplicated:");
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383 output.shouldHaveExitValue(0);
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384 }
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385
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386 public static void testTableResize() throws Exception {
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387 // Test with StringDeduplicationResizeALot
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388 OutputAnalyzer output = DeduplicationTest.run(LargeNumberOfStrings,
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389 DefaultAgeThreshold,
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390 YoungGC,
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391 "-XX:+PrintGC",
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392 "-XX:+PrintStringDeduplicationStatistics",
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393 "-XX:+StringDeduplicationResizeALot");
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394 output.shouldContain("GC concurrent-string-deduplication");
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395 output.shouldContain("Deduplicated:");
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396 output.shouldNotContain("Resize Count: 0");
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397 output.shouldHaveExitValue(0);
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398 }
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399
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400 public static void testTableRehash() throws Exception {
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401 // Test with StringDeduplicationRehashALot
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402 OutputAnalyzer output = DeduplicationTest.run(LargeNumberOfStrings,
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403 DefaultAgeThreshold,
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404 YoungGC,
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405 "-XX:+PrintGC",
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406 "-XX:+PrintStringDeduplicationStatistics",
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407 "-XX:+StringDeduplicationRehashALot");
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408 output.shouldContain("GC concurrent-string-deduplication");
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409 output.shouldContain("Deduplicated:");
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410 output.shouldNotContain("Rehash Count: 0");
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411 output.shouldNotContain("Hash Seed: 0x0");
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412 output.shouldHaveExitValue(0);
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413 }
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414
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415 public static void testAgeThreshold() throws Exception {
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416 OutputAnalyzer output;
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417
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418 // Test with max age theshold
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419 output = DeduplicationTest.run(SmallNumberOfStrings,
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420 MaxAgeThreshold,
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421 YoungGC,
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422 "-XX:+PrintGC",
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423 "-XX:+PrintStringDeduplicationStatistics");
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424 output.shouldContain("GC concurrent-string-deduplication");
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425 output.shouldContain("Deduplicated:");
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426 output.shouldHaveExitValue(0);
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427
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428 // Test with min age theshold
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429 output = DeduplicationTest.run(SmallNumberOfStrings,
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430 MinAgeThreshold,
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431 YoungGC,
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432 "-XX:+PrintGC",
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433 "-XX:+PrintStringDeduplicationStatistics");
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434 output.shouldContain("GC concurrent-string-deduplication");
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435 output.shouldContain("Deduplicated:");
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436 output.shouldHaveExitValue(0);
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437
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438 // Test with too low age threshold
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439 output = DeduplicationTest.run(SmallNumberOfStrings,
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440 TooLowAgeThreshold,
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441 YoungGC);
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442 output.shouldContain("StringDeduplicationAgeThreshold of " + TooLowAgeThreshold +
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443 " is invalid; must be between " + MinAgeThreshold + " and " + MaxAgeThreshold);
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444 output.shouldHaveExitValue(1);
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445
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446 // Test with too high age threshold
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447 output = DeduplicationTest.run(SmallNumberOfStrings,
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448 TooHighAgeThreshold,
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449 YoungGC);
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450 output.shouldContain("StringDeduplicationAgeThreshold of " + TooHighAgeThreshold +
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451 " is invalid; must be between " + MinAgeThreshold + " and " + MaxAgeThreshold);
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452 output.shouldHaveExitValue(1);
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453 }
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454
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455 public static void testPrintOptions() throws Exception {
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456 OutputAnalyzer output;
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457
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458 // Test without PrintGC and without PrintStringDeduplicationStatistics
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459 output = DeduplicationTest.run(SmallNumberOfStrings,
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460 DefaultAgeThreshold,
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461 YoungGC);
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462 output.shouldNotContain("GC concurrent-string-deduplication");
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463 output.shouldNotContain("Deduplicated:");
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464 output.shouldHaveExitValue(0);
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465
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466 // Test with PrintGC but without PrintStringDeduplicationStatistics
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467 output = DeduplicationTest.run(SmallNumberOfStrings,
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468 DefaultAgeThreshold,
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469 YoungGC,
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470 "-XX:+PrintGC");
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471 output.shouldContain("GC concurrent-string-deduplication");
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472 output.shouldNotContain("Deduplicated:");
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473 output.shouldHaveExitValue(0);
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474 }
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475
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476 public static void testInterned() throws Exception {
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477 // Test that interned strings are deduplicated before being interned
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478 OutputAnalyzer output = InternedTest.run();
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479 output.shouldHaveExitValue(0);
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480 }
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481
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482 public static void testMemoryUsage() throws Exception {
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483 // Test that memory usage is reduced after deduplication
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484 OutputAnalyzer output;
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485 final String usagePattern = "Heap Memory Usage: (\\d+)";
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486
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487 // Run without deduplication
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488 output = MemoryUsageTest.run(false);
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489 output.shouldHaveExitValue(0);
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490 final long memoryUsageWithoutDedup = Long.parseLong(output.firstMatch(usagePattern, 1));
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491
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492 // Run with deduplication
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493 output = MemoryUsageTest.run(true);
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494 output.shouldHaveExitValue(0);
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495 final long memoryUsageWithDedup = Long.parseLong(output.firstMatch(usagePattern, 1));
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496
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497 // Calculate expected memory usage with deduplication enabled. This calculation does
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498 // not take alignment and padding into account, so it's a conservative estimate.
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499 final long sizeOfChar = 2; // bytes
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500 final long bytesSaved = (LargeNumberOfStrings - 1) * (StringLength * sizeOfChar + unsafe.ARRAY_CHAR_BASE_OFFSET);
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501 final long memoryUsageWithDedupExpected = memoryUsageWithoutDedup - bytesSaved;
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502
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503 System.out.println("Memory usage summary:");
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504 System.out.println(" memoryUsageWithoutDedup: " + memoryUsageWithoutDedup);
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505 System.out.println(" memoryUsageWithDedup: " + memoryUsageWithDedup);
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506 System.out.println(" memoryUsageWithDedupExpected: " + memoryUsageWithDedupExpected);
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507
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508 if (memoryUsageWithDedup > memoryUsageWithDedupExpected) {
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509 throw new Exception("Unexpected memory usage, memoryUsageWithDedup should less or equal to memoryUsageWithDedupExpected");
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510 }
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511 }
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512 }
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