test/gc/g1/TestShrinkAuxiliaryData.java

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rev 7885 : 8061715:gc/g1/TestShrinkAuxiliaryData15.java fails
   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 
  24 import static com.oracle.java.testlibrary.Asserts.assertLessThanOrEqual;
  25 import com.oracle.java.testlibrary.OutputAnalyzer;
  26 import com.oracle.java.testlibrary.Platform;
  27 import com.oracle.java.testlibrary.ProcessTools;
  28 import com.oracle.java.testlibrary.Utils;
  29 import java.io.IOException;
  30 import java.lang.management.ManagementFactory;
  31 import java.lang.management.MemoryUsage;
  32 import java.text.DecimalFormat;
  33 import java.text.DecimalFormatSymbols;
  34 import java.util.ArrayList;
  35 import java.util.Arrays;
  36 import java.util.Collections;
  37 import java.util.LinkedList;
  38 import java.util.List;
  39 import sun.misc.Unsafe;

  40 
  41 public class TestShrinkAuxiliaryData {
  42 


  43     private final static String[] initialOpts = new String[]{
  44         "-XX:MinHeapFreeRatio=10",
  45         "-XX:MaxHeapFreeRatio=11",
  46         "-XX:+UseG1GC",
  47         "-XX:G1HeapRegionSize=1m",
  48         "-XX:-ExplicitGCInvokesConcurrent",
  49         "-XX:+PrintGCDetails"



  50     };
  51 
  52     private final int RSetCacheSize;
  53 
  54     protected TestShrinkAuxiliaryData(int RSetCacheSize) {
  55         this.RSetCacheSize = RSetCacheSize;
  56     }
  57 
  58     protected void test() throws Exception {
  59         ArrayList<String> vmOpts = new ArrayList();
  60         Collections.addAll(vmOpts, initialOpts);
  61 
  62         int maxCacheSize = Math.max(0, Math.min(31, getMaxCacheSize()));
  63         if (maxCacheSize < RSetCacheSize) {
  64             System.out.format("Skiping test for %d cache size due max cache size %d",
  65                     RSetCacheSize, maxCacheSize
  66             );
  67             return;
  68         }
  69 
  70         printTestInfo(maxCacheSize);
  71 
  72         vmOpts.add("-XX:G1ConcRSLogCacheSize=" + RSetCacheSize);
  73         vmOpts.addAll(Arrays.asList(Utils.getTestJavaOpts()));
  74 
  75         // for 32 bits ObjectAlignmentInBytes is not a option
  76         if (Platform.is32bit()) {
  77             ArrayList<String> vmOptsWithoutAlign = new ArrayList(vmOpts);
  78             vmOptsWithoutAlign.add(ShrinkAuxiliaryDataTest.class.getName());
  79             performTest(vmOptsWithoutAlign);
  80             return;
  81         }
  82 
  83         for (int alignment = 3; alignment <= 8; alignment++) {
  84             ArrayList<String> vmOptsWithAlign = new ArrayList(vmOpts);
  85             vmOptsWithAlign.add("-XX:ObjectAlignmentInBytes="
  86                     + (int) Math.pow(2, alignment));
  87             vmOptsWithAlign.add(ShrinkAuxiliaryDataTest.class.getName());
  88 
  89             performTest(vmOptsWithAlign);
  90         }
  91     }
  92 
  93     private void performTest(List<String> opts) throws Exception {
  94         ProcessBuilder pb
  95                        = ProcessTools.createJavaProcessBuilder(
  96                 opts.toArray(new String[opts.size()])
  97         );
  98 
  99         OutputAnalyzer output = new OutputAnalyzer(pb.start());


 100         output.shouldHaveExitValue(0);
 101     }
 102 
 103     private void printTestInfo(int maxCacheSize) {
 104 
 105         DecimalFormat grouped = new DecimalFormat("000,000");
 106         DecimalFormatSymbols formatSymbols = grouped.getDecimalFormatSymbols();
 107         formatSymbols.setGroupingSeparator(' ');
 108         grouped.setDecimalFormatSymbols(formatSymbols);
 109 
 110         System.out.format("Test will use %s bytes of memory of %s available%n"

 111                 + "Available memory is %s with %d bytes pointer size - can save %s pointers%n"
 112                 + "Max cache size: 2^%d = %s elements%n",
 113                 grouped.format(ShrinkAuxiliaryDataTest.getMemoryUsedByTest()),
 114                 grouped.format(Runtime.getRuntime().freeMemory()),
 115                 grouped.format(Runtime.getRuntime().freeMemory()
 116                         - ShrinkAuxiliaryDataTest.getMemoryUsedByTest()),
 117                 Unsafe.ADDRESS_SIZE,
 118                 grouped.format((Runtime.getRuntime().freeMemory()
 119                         - ShrinkAuxiliaryDataTest.getMemoryUsedByTest())
 120                         / Unsafe.ADDRESS_SIZE),
 121                 maxCacheSize,
 122                 grouped.format((int) Math.pow(2, maxCacheSize))
 123         );
 124     }
 125 
 126     /**
 127      * Detects maximum possible size of G1ConcRSLogCacheSize available for
 128      * current process based on maximum available process memory size
 129      *
 130      * @return power of two
 131      */
 132     private static int getMaxCacheSize() {
 133         long availableMemory = Runtime.getRuntime().freeMemory()
 134                 - ShrinkAuxiliaryDataTest.getMemoryUsedByTest() - 1l;
 135         if (availableMemory <= 0) {
 136             return 0;
 137         }

 138         long availablePointersCount = availableMemory / Unsafe.ADDRESS_SIZE;
 139         return (63 - (int) Long.numberOfLeadingZeros(availablePointersCount));
 140     }
 141 
 142     static class ShrinkAuxiliaryDataTest {
 143 
 144         public static void main(String[] args) throws IOException {
 145             int iterateCount = DEFAULT_ITERATION_COUNT;
 146 
 147             if (args.length > 0) {
 148                 try {
 149                     iterateCount = Integer.parseInt(args[0]);
 150                 } catch (NumberFormatException e) {
 151                     //num_iterate remains default
























 152                 }








 153             }
 154 
 155             new ShrinkAuxiliaryDataTest().test(iterateCount);
 156         }
 157 
 158         class GarbageObject {
 159 
 160             private final List<byte[]> payload = new ArrayList();
 161             private final List<GarbageObject> ref = new LinkedList();
 162 
 163             public GarbageObject(int size) {
 164                 payload.add(new byte[size]);
 165             }
 166 
 167             public void addRef(GarbageObject g) {
 168                 ref.add(g);
 169             }
 170 
 171             public void mutate() {
 172                 if (!payload.isEmpty() && payload.get(0).length > 0) {
 173                     payload.get(0)[0] = (byte) (Math.random() * Byte.MAX_VALUE);
 174                 }
 175             }
 176         }
 177 
 178         private final List<GarbageObject> garbage = new ArrayList();
 179 
 180         public void test(int num_iterate) throws IOException {



 181 
 182             allocate();
 183             link();
 184             mutate();
 185             deallocate();
 186 
 187             MemoryUsage muBeforeHeap
 188                         = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
 189             MemoryUsage muBeforeNonHeap
 190                         = ManagementFactory.getMemoryMXBean().getNonHeapMemoryUsage();

 191 
 192             for (int i = 0; i < num_iterate; i++) {
 193                 allocate();
 194                 link();
 195                 mutate();
 196                 deallocate();
 197             }
 198 

 199             System.gc();
 200             MemoryUsage muAfterHeap
 201                         = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
 202             MemoryUsage muAfterNonHeap
 203                         = ManagementFactory.getMemoryMXBean().getNonHeapMemoryUsage();
 204 
 205             assertLessThanOrEqual(muAfterHeap.getCommitted(), muBeforeHeap.getCommitted(),
 206                     String.format("heap decommit failed - after > before: %d > %d",
 207                             muAfterHeap.getCommitted(), muBeforeHeap.getCommitted()







 208                     )
 209             );
 210 
 211             if (muAfterHeap.getCommitted() < muBeforeHeap.getCommitted()) {
 212                 assertLessThanOrEqual(muAfterNonHeap.getCommitted(), muBeforeNonHeap.getCommitted(),
 213                         String.format("non-heap decommit failed - after > before: %d > %d",
 214                                 muAfterNonHeap.getCommitted(), muBeforeNonHeap.getCommitted()





 215                         )
 216                 );
 217             }
 218         }
 219 
 220         private void allocate() {
 221             for (int r = 0; r < REGIONS_TO_ALLOCATE; r++) {
 222                 for (int i = 0; i < NUM_OBJECTS_PER_REGION; i++) {
 223                     GarbageObject g = new GarbageObject(REGION_SIZE
 224                             / NUM_OBJECTS_PER_REGION);
 225                     garbage.add(g);
 226                 }
 227             }
 228         }
 229 
 230         /**
 231          * Iterate through all allocated objects, and link to objects in another
 232          * regions
 233          */
 234         private void link() {
 235             for (int ig = 0; ig < garbage.size(); ig++) {
 236                 int regionNumber = ig / NUM_OBJECTS_PER_REGION;
 237 
 238                 for (int i = 0; i < NUM_LINKS; i++) {
 239                     int regionToLink;
 240                     do {
 241                         regionToLink = (int) (Math.random()
 242                                 * REGIONS_TO_ALLOCATE);
 243                     } while (regionToLink == regionNumber);
 244 
 245                     // get random garbage object from random region
 246                     garbage.get(ig).addRef(garbage.get(regionToLink
 247                             * NUM_OBJECTS_PER_REGION + (int) (Math.random()
 248                             * NUM_OBJECTS_PER_REGION)));
 249                 }
 250             }
 251         }
 252 
 253         private void mutate() {
 254             for (int ig = 0; ig < garbage.size(); ig++) {
 255                 garbage.get(ig).mutate();
 256             }
 257         }
 258 
 259         private void deallocate() {
 260             garbage.clear();
 261             System.gc();
 262         }
 263 
 264         static long getMemoryUsedByTest() {
 265             return REGIONS_TO_ALLOCATE * REGION_SIZE;
 266         }
 267 
 268         private static final int REGION_SIZE = 1024 * 1024;
 269         private static final int DEFAULT_ITERATION_COUNT = 1;   // iterate main scenario
 270         private static final int REGIONS_TO_ALLOCATE = 5;
 271         private static final int NUM_OBJECTS_PER_REGION = 10;
 272         private static final int NUM_LINKS = 20; // how many links create for each object
 273 
 274     }
 275 }
   1 /*
   2  * Copyright (c) 2014, 2015, 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 
  24 import com.oracle.java.testlibrary.Asserts;
  25 import com.oracle.java.testlibrary.OutputAnalyzer;
  26 import com.oracle.java.testlibrary.Platform;
  27 import com.oracle.java.testlibrary.ProcessTools;
  28 import com.oracle.java.testlibrary.Utils;
  29 import java.io.IOException;
  30 import java.lang.management.ManagementFactory;
  31 import java.lang.management.MemoryUsage;
  32 import java.text.DecimalFormat;
  33 import java.text.DecimalFormatSymbols;
  34 import java.util.ArrayList;
  35 import java.util.Arrays;
  36 import java.util.Collections;
  37 import java.util.LinkedList;
  38 import java.util.List;
  39 import sun.misc.Unsafe; // for ADDRESS_SIZE
  40 import sun.hotspot.WhiteBox;
  41 
  42 public class TestShrinkAuxiliaryData {
  43 
  44     private static final int REGION_SIZE = 1024 * 1024;
  45 
  46     private final static String[] initialOpts = new String[]{
  47         "-XX:MinHeapFreeRatio=10",
  48         "-XX:MaxHeapFreeRatio=11",
  49         "-XX:+UseG1GC",
  50         "-XX:G1HeapRegionSize=" + REGION_SIZE,
  51         "-XX:-ExplicitGCInvokesConcurrent",
  52         "-XX:+PrintGCDetails",
  53         "-XX:+UnlockDiagnosticVMOptions",
  54         "-XX:+WhiteBoxAPI",
  55         "-Xbootclasspath/a:.",
  56     };
  57 
  58     private final int hotCardTableSize;
  59 
  60     protected TestShrinkAuxiliaryData(int hotCardTableSize) {
  61         this.hotCardTableSize = hotCardTableSize;
  62     }
  63 
  64     protected void test() throws Exception {
  65         ArrayList<String> vmOpts = new ArrayList();
  66         Collections.addAll(vmOpts, initialOpts);
  67 
  68         int maxCacheSize = Math.max(0, Math.min(31, getMaxCacheSize()));
  69         if (maxCacheSize < hotCardTableSize) {
  70             System.out.format("Skiping test for %d cache size due max cache size %d",
  71                     hotCardTableSize, maxCacheSize
  72             );
  73             return;
  74         }
  75 
  76         printTestInfo(maxCacheSize);
  77 
  78         vmOpts.add("-XX:G1ConcRSLogCacheSize=" + hotCardTableSize);
  79         vmOpts.addAll(Arrays.asList(Utils.getTestJavaOpts()));
  80 
  81         // for 32 bits ObjectAlignmentInBytes is not a option
  82         if (Platform.is32bit()) {
  83             ArrayList<String> vmOptsWithoutAlign = new ArrayList(vmOpts);
  84             vmOptsWithoutAlign.add(ShrinkAuxiliaryDataTest.class.getName());
  85             performTest(vmOptsWithoutAlign);
  86             return;
  87         }
  88 
  89         for (int alignment = 3; alignment <= 8; alignment++) {
  90             ArrayList<String> vmOptsWithAlign = new ArrayList(vmOpts);
  91             vmOptsWithAlign.add("-XX:ObjectAlignmentInBytes="
  92                     + (int) Math.pow(2, alignment));
  93             vmOptsWithAlign.add(ShrinkAuxiliaryDataTest.class.getName());
  94 
  95             performTest(vmOptsWithAlign);
  96         }
  97     }
  98 
  99     private void performTest(List<String> opts) throws Exception {
 100         ProcessBuilder pb
 101                 = ProcessTools.createJavaProcessBuilder(
 102                         opts.toArray(new String[opts.size()])
 103                 );
 104 
 105         OutputAnalyzer output = new OutputAnalyzer(pb.start());
 106         System.out.println(output.getStdout());
 107         System.err.println(output.getStderr());
 108         output.shouldHaveExitValue(0);
 109     }
 110 
 111     private void printTestInfo(int maxCacheSize) {
 112 
 113         DecimalFormat grouped = new DecimalFormat("000,000");
 114         DecimalFormatSymbols formatSymbols = grouped.getDecimalFormatSymbols();
 115         formatSymbols.setGroupingSeparator(' ');
 116         grouped.setDecimalFormatSymbols(formatSymbols);
 117 
 118         System.out.format(
 119                 "Test will use %s bytes of memory of %s available%n"
 120                 + "Available memory is %s with %d bytes pointer size - can save %s pointers%n"
 121                 + "Max cache size: 2^%d = %s elements%n",
 122                 grouped.format(ShrinkAuxiliaryDataTest.getMemoryUsedByTest()),
 123                 grouped.format(Runtime.getRuntime().maxMemory()),
 124                 grouped.format(Runtime.getRuntime().maxMemory()
 125                         - ShrinkAuxiliaryDataTest.getMemoryUsedByTest()),
 126                 Unsafe.ADDRESS_SIZE,
 127                 grouped.format((Runtime.getRuntime().freeMemory()
 128                         - ShrinkAuxiliaryDataTest.getMemoryUsedByTest())
 129                         / Unsafe.ADDRESS_SIZE),
 130                 maxCacheSize,
 131                 grouped.format((int) Math.pow(2, maxCacheSize))
 132         );
 133     }
 134 
 135     /**
 136      * Detects maximum possible size of G1ConcRSLogCacheSize available for
 137      * current process based on maximum available process memory size
 138      *
 139      * @return power of two
 140      */
 141     private static int getMaxCacheSize() {
 142         long availableMemory = Runtime.getRuntime().freeMemory()
 143                 - ShrinkAuxiliaryDataTest.getMemoryUsedByTest() - 1l;
 144         if (availableMemory <= 0) {
 145             return 0;
 146         }
 147 
 148         long availablePointersCount = availableMemory / Unsafe.ADDRESS_SIZE;
 149         return (63 - (int) Long.numberOfLeadingZeros(availablePointersCount));
 150     }
 151 
 152     static class ShrinkAuxiliaryDataTest {
 153 
 154         public static void main(String[] args) throws IOException {

 155 
 156             ShrinkAuxiliaryDataTest testCase = new ShrinkAuxiliaryDataTest();
 157 
 158             if (!testCase.checkEnvApplicability()) {
 159                 return;
 160             }
 161 
 162             testCase.test();
 163         }
 164 
 165         /**
 166          * Checks is this environment suitable to run this test
 167          * - memory is enough to decommit (page size is not big)
 168          * - RSet cache size is not too big
 169          *
 170          * @return true if test could run, false if test should be skipped
 171          */
 172         protected boolean checkEnvApplicability() {
 173 
 174             int pageSize = WhiteBox.getWhiteBox().getVMPageSize();
 175             System.out.println( "Page size = " + pageSize
 176                     + " region size = " + REGION_SIZE
 177                     + " aux data ~= " + (REGION_SIZE * 3 / 100));
 178             // If auxdata size will be less than page size it wouldn't decommit.
 179             // Auxiliary data size is about ~3.6% of heap size.
 180             if (pageSize >= REGION_SIZE * 3 / 100) {
 181                 System.out.format("Skipping test for too large page size = %d",
 182                        pageSize
 183                 );
 184                 return false;
 185             }
 186 
 187             if (REGION_SIZE * REGIONS_TO_ALLOCATE > Runtime.getRuntime().maxMemory()) {
 188                 System.out.format("Skipping test for too low available memory. "
 189                         + "Need %d, available %d",
 190                         REGION_SIZE * REGIONS_TO_ALLOCATE,
 191                         Runtime.getRuntime().maxMemory()
 192                 );
 193                 return false;
 194             }
 195 
 196             return true;
 197         }
 198 
 199         class GarbageObject {
 200 
 201             private final List<byte[]> payload = new ArrayList();
 202             private final List<GarbageObject> ref = new LinkedList();
 203 
 204             public GarbageObject(int size) {
 205                 payload.add(new byte[size]);
 206             }
 207 
 208             public void addRef(GarbageObject g) {
 209                 ref.add(g);
 210             }
 211 
 212             public void mutate() {
 213                 if (!payload.isEmpty() && payload.get(0).length > 0) {
 214                     payload.get(0)[0] = (byte) (Math.random() * Byte.MAX_VALUE);
 215                 }
 216             }
 217         }
 218 
 219         private final List<GarbageObject> garbage = new ArrayList();
 220 
 221         public void test() throws IOException {
 222 
 223             MemoryUsage muFull, muFree, muAuxDataFull, muAuxDataFree;
 224             float auxFull, auxFree;
 225 
 226             allocate();
 227             link();
 228             mutate();

 229 
 230             muFull = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
 231             long numUsedRegions = WhiteBox.getWhiteBox().g1NumMaxRegions()
 232                     - WhiteBox.getWhiteBox().g1NumFreeRegions();
 233             muAuxDataFull = WhiteBox.getWhiteBox().g1AuxiliaryMemoryUsage();
 234             auxFull = (float)muAuxDataFull.getUsed() / numUsedRegions;
 235 
 236             System.out.format("Full aux data  ratio= %f, regions max= %d, used= %d\n",
 237                     auxFull, WhiteBox.getWhiteBox().g1NumMaxRegions(), numUsedRegions
 238             );



 239 
 240             deallocate();
 241             System.gc();
 242 
 243             muFree = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
 244             muAuxDataFree = WhiteBox.getWhiteBox().g1AuxiliaryMemoryUsage();
 245 
 246             numUsedRegions = WhiteBox.getWhiteBox().g1NumMaxRegions()
 247                     - WhiteBox.getWhiteBox().g1NumFreeRegions();
 248             auxFree = (float)muAuxDataFree.getUsed() / numUsedRegions;
 249 
 250             System.out.format("Free aux data ratio= %f, regions max= %d, used= %d\n",
 251                     auxFree, WhiteBox.getWhiteBox().g1NumMaxRegions(), numUsedRegions
 252             );
 253 
 254             Asserts.assertLessThanOrEqual(muFree.getCommitted(), muFull.getCommitted(),
 255                     String.format("heap decommit failed - full > free: %d > %d",
 256                             muFree.getCommitted(), muFull.getCommitted()
 257                     )
 258             );
 259 
 260             System.out.format("State               used   committed\n");
 261             System.out.format("Full aux data: %10d %10d\n", muAuxDataFull.getUsed(), muAuxDataFull.getCommitted());
 262             System.out.format("Free aux data: %10d %10d\n", muAuxDataFree.getUsed(), muAuxDataFree.getCommitted());
 263 
 264             // if decommited check that aux data has same ratio
 265             if (muFree.getCommitted() < muFull.getCommitted()) {
 266                 Asserts.assertLessThanOrEqual(auxFree, auxFull,
 267                         String.format("auxiliary data decommit failed - full > free: %f > %f",
 268                                 auxFree, auxFull
 269                         )
 270                 );
 271             }
 272         }
 273 
 274         private void allocate() {
 275             for (int r = 0; r < REGIONS_TO_ALLOCATE; r++) {
 276                 for (int i = 0; i < NUM_OBJECTS_PER_REGION; i++) {
 277                     GarbageObject g = new GarbageObject(REGION_SIZE
 278                             / NUM_OBJECTS_PER_REGION);
 279                     garbage.add(g);
 280                 }
 281             }
 282         }
 283 
 284         /**
 285          * Iterate through all allocated objects, and link to objects in another
 286          * regions
 287          */
 288         private void link() {
 289             for (int ig = 0; ig < garbage.size(); ig++) {
 290                 int regionNumber = ig / NUM_OBJECTS_PER_REGION;
 291 
 292                 for (int i = 0; i < NUM_LINKS; i++) {
 293                     int regionToLink;
 294                     do {
 295                         regionToLink = (int) (Math.random() * REGIONS_TO_ALLOCATE);

 296                     } while (regionToLink == regionNumber);
 297 
 298                     // get random garbage object from random region
 299                     garbage.get(ig).addRef(garbage.get(regionToLink
 300                             * NUM_OBJECTS_PER_REGION + (int) (Math.random()
 301                             * NUM_OBJECTS_PER_REGION)));
 302                 }
 303             }
 304         }
 305 
 306         private void mutate() {
 307             for (int ig = 0; ig < garbage.size(); ig++) {
 308                 garbage.get(ig).mutate();
 309             }
 310         }
 311 
 312         private void deallocate() {
 313             garbage.clear();
 314             System.gc();
 315         }
 316 
 317         static long getMemoryUsedByTest() {
 318             return REGIONS_TO_ALLOCATE * REGION_SIZE;
 319         }
 320 
 321         private static final int REGIONS_TO_ALLOCATE = 100;


 322         private static final int NUM_OBJECTS_PER_REGION = 10;
 323         private static final int NUM_LINKS = 20; // how many links create for each object

 324     }
 325 }