1 /* 2 * Copyright (c) 2000, 2020, 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 25 // 26 // The ObjectHeap is an abstraction over all generations in the VM 27 // It gives access to all present objects and classes. 28 // 29 30 package sun.jvm.hotspot.oops; 31 32 import java.util.*; 33 34 import sun.jvm.hotspot.debugger.*; 35 import sun.jvm.hotspot.gc.shared.*; 36 import sun.jvm.hotspot.gc.epsilon.*; 37 import sun.jvm.hotspot.gc.g1.*; 38 import sun.jvm.hotspot.gc.shenandoah.*; 39 import sun.jvm.hotspot.gc.parallel.*; 40 import sun.jvm.hotspot.gc.z.*; 41 import sun.jvm.hotspot.memory.*; 42 import sun.jvm.hotspot.runtime.*; 43 import sun.jvm.hotspot.types.*; 44 import sun.jvm.hotspot.utilities.*; 45 46 public class ObjectHeap { 47 48 private static final boolean DEBUG; 49 50 static { 51 DEBUG = System.getProperty("sun.jvm.hotspot.oops.ObjectHeap.DEBUG") != null; 52 } 53 ObjectHeap(TypeDataBase db)54 public ObjectHeap(TypeDataBase db) throws WrongTypeException { 55 // Get commonly used sizes of basic types 56 oopSize = VM.getVM().getOopSize(); 57 byteSize = db.getJByteType().getSize(); 58 charSize = db.getJCharType().getSize(); 59 booleanSize = db.getJBooleanType().getSize(); 60 intSize = db.getJIntType().getSize(); 61 shortSize = db.getJShortType().getSize(); 62 longSize = db.getJLongType().getSize(); 63 floatSize = db.getJFloatType().getSize(); 64 doubleSize = db.getJDoubleType().getSize(); 65 } 66 67 /** Comparison operation for oops, either or both of which may be null */ equal(Oop o1, Oop o2)68 public boolean equal(Oop o1, Oop o2) { 69 if (o1 != null) return o1.equals(o2); 70 return (o2 == null); 71 } 72 73 // Cached sizes of basic types 74 private long oopSize; 75 private long byteSize; 76 private long charSize; 77 private long booleanSize; 78 private long intSize; 79 private long shortSize; 80 private long longSize; 81 private long floatSize; 82 private long doubleSize; 83 getOopSize()84 public long getOopSize() { return oopSize; } getByteSize()85 public long getByteSize() { return byteSize; } getCharSize()86 public long getCharSize() { return charSize; } getBooleanSize()87 public long getBooleanSize() { return booleanSize; } getIntSize()88 public long getIntSize() { return intSize; } getShortSize()89 public long getShortSize() { return shortSize; } getLongSize()90 public long getLongSize() { return longSize; } getFloatSize()91 public long getFloatSize() { return floatSize; } getDoubleSize()92 public long getDoubleSize() { return doubleSize; } 93 94 /** an interface to filter objects while walking heap */ 95 public static interface ObjectFilter { canInclude(Oop obj)96 public boolean canInclude(Oop obj); 97 } 98 99 /** The base heap iteration mechanism */ iterate(HeapVisitor visitor)100 public void iterate(HeapVisitor visitor) { 101 iterateLiveRegions(collectLiveRegions(), visitor, null); 102 } 103 104 /** iterate objects satisfying a specified ObjectFilter */ iterate(HeapVisitor visitor, ObjectFilter of)105 public void iterate(HeapVisitor visitor, ObjectFilter of) { 106 iterateLiveRegions(collectLiveRegions(), visitor, of); 107 } 108 109 /** iterate objects of given Klass. param 'includeSubtypes' tells whether to 110 * include objects of subtypes or not */ iterateObjectsOfKlass(HeapVisitor visitor, final Klass k, boolean includeSubtypes)111 public void iterateObjectsOfKlass(HeapVisitor visitor, final Klass k, boolean includeSubtypes) { 112 if (includeSubtypes) { 113 if (k.isFinal()) { 114 // do the simpler "exact" klass loop 115 iterateExact(visitor, k); 116 } else { 117 iterateSubtypes(visitor, k); 118 } 119 } else { 120 // there can no object of abstract classes and interfaces 121 if (!k.isAbstract() && !k.isInterface()) { 122 iterateExact(visitor, k); 123 } 124 } 125 } 126 127 /** iterate objects of given Klass (objects of subtypes included) */ iterateObjectsOfKlass(HeapVisitor visitor, final Klass k)128 public void iterateObjectsOfKlass(HeapVisitor visitor, final Klass k) { 129 iterateObjectsOfKlass(visitor, k, true); 130 } 131 132 /** This routine can be used to iterate through the heap at an 133 extremely low level (stepping word-by-word) to provide the 134 ability to do very low-level debugging */ iterateRaw(RawHeapVisitor visitor)135 public void iterateRaw(RawHeapVisitor visitor) { 136 List<Address> liveRegions = collectLiveRegions(); 137 138 // Summarize size 139 long totalSize = 0; 140 for (int i = 0; i < liveRegions.size(); i += 2) { 141 Address bottom = (Address) liveRegions.get(i); 142 Address top = (Address) liveRegions.get(i+1); 143 totalSize += top.minus(bottom); 144 } 145 visitor.prologue(totalSize); 146 147 for (int i = 0; i < liveRegions.size(); i += 2) { 148 Address bottom = (Address) liveRegions.get(i); 149 Address top = (Address) liveRegions.get(i+1); 150 151 // Traverses the space from bottom to top 152 while (bottom.lessThan(top)) { 153 visitor.visitAddress(bottom); 154 bottom = bottom.addOffsetTo(VM.getVM().getAddressSize()); 155 } 156 } 157 158 visitor.epilogue(); 159 } 160 isValidMethod(Address handle)161 public boolean isValidMethod(Address handle) { 162 try { 163 Method m = (Method)Metadata.instantiateWrapperFor(handle); 164 return true; 165 } catch (Exception e) { 166 return false; 167 } 168 } 169 170 // Creates an instance from the Oop hierarchy based based on the handle newOop(OopHandle handle)171 public Oop newOop(OopHandle handle) { 172 // The only known way to detect the right type of an oop is 173 // traversing the class chain until a well-known klass is recognized. 174 // A more direct solution would require the klasses to expose 175 // the C++ vtbl structure. 176 177 // Handle the null reference 178 if (handle == null) return null; 179 180 // Then check if obj.klass() is one of the root objects 181 Klass klass = Oop.getKlassForOopHandle(handle); 182 if (klass != null) { 183 if (klass instanceof TypeArrayKlass) return new TypeArray(handle, this); 184 if (klass instanceof ObjArrayKlass) return new ObjArray(handle, this); 185 if (klass instanceof InstanceKlass) return new Instance(handle, this); 186 } 187 188 if (DEBUG) { 189 System.err.println("Unknown oop at " + handle); 190 System.err.println("Oop's klass is " + klass); 191 } 192 193 throw new UnknownOopException(); 194 } 195 196 // Print all objects in the object heap print()197 public void print() { 198 HeapPrinter printer = new HeapPrinter(System.out); 199 iterate(printer); 200 } 201 202 //--------------------------------------------------------------------------- 203 // Internals only below this point 204 // 205 iterateExact(HeapVisitor visitor, final Klass k)206 private void iterateExact(HeapVisitor visitor, final Klass k) { 207 iterateLiveRegions(collectLiveRegions(), visitor, new ObjectFilter() { 208 public boolean canInclude(Oop obj) { 209 Klass tk = obj.getKlass(); 210 // null Klass is seen sometimes! 211 return (tk != null && tk.equals(k)); 212 } 213 }); 214 } 215 iterateSubtypes(HeapVisitor visitor, final Klass k)216 private void iterateSubtypes(HeapVisitor visitor, final Klass k) { 217 iterateLiveRegions(collectLiveRegions(), visitor, new ObjectFilter() { 218 public boolean canInclude(Oop obj) { 219 Klass tk = obj.getKlass(); 220 // null Klass is seen sometimes! 221 return (tk != null && tk.isSubtypeOf(k)); 222 } 223 }); 224 } 225 iterateLiveRegions(List<Address> liveRegions, HeapVisitor visitor, ObjectFilter of)226 private void iterateLiveRegions(List<Address> liveRegions, HeapVisitor visitor, ObjectFilter of) { 227 // Summarize size 228 long totalSize = 0; 229 for (int i = 0; i < liveRegions.size(); i += 2) { 230 Address bottom = (Address) liveRegions.get(i); 231 Address top = (Address) liveRegions.get(i+1); 232 totalSize += top.minus(bottom); 233 } 234 visitor.prologue(totalSize); 235 236 for (int i = 0; i < liveRegions.size(); i += 2) { 237 Address bottom = (Address) liveRegions.get(i); 238 Address top = (Address) liveRegions.get(i+1); 239 240 try { 241 // Traverses the space from bottom to top 242 OopHandle handle = bottom.addOffsetToAsOopHandle(0); 243 244 while (handle.lessThan(top)) { 245 Oop obj = null; 246 247 obj = newOop(handle); 248 if (obj == null) { 249 throw new UnknownOopException(); 250 } 251 if (of == null || of.canInclude(obj)) { 252 if (visitor.doObj(obj)) { 253 // doObj() returns true to abort this loop. 254 break; 255 } 256 } 257 258 handle = handle.addOffsetToAsOopHandle(obj.getObjectSize()); 259 } 260 } catch (AddressException | UnknownOopException | WrongTypeException e) { 261 // This is okay at the top of these regions 262 } 263 } 264 265 visitor.epilogue(); 266 } 267 268 private static class LiveRegionsCollector implements LiveRegionsClosure { LiveRegionsCollector(List<Address> l)269 LiveRegionsCollector(List<Address> l) { 270 liveRegions = l; 271 } 272 273 @Override doLiveRegions(LiveRegionsProvider lrp)274 public void doLiveRegions(LiveRegionsProvider lrp) { 275 for (MemRegion reg : lrp.getLiveRegions()) { 276 Address top = reg.end(); 277 Address bottom = reg.start(); 278 if (Assert.ASSERTS_ENABLED) { 279 Assert.that(top != null, "top address in a live region should not be null"); 280 } 281 if (Assert.ASSERTS_ENABLED) { 282 Assert.that(bottom != null, "bottom address in a live region should not be null"); 283 } 284 liveRegions.add(top); 285 liveRegions.add(bottom); 286 if (DEBUG) { 287 System.err.println("Live region: " + lrp + ": " + bottom + ", " + top); 288 } 289 } 290 } 291 292 private List<Address> liveRegions; 293 } 294 295 // Returns a List<Address> where the addresses come in pairs. These 296 // designate the live regions of the heap. collectLiveRegions()297 private List<Address> collectLiveRegions() { 298 // We want to iterate through all live portions of the heap, but 299 // do not want to abort the heap traversal prematurely if we find 300 // a problem (like an allocated but uninitialized object at the 301 // top of a generation). To do this we enumerate all generations' 302 // bottom and top regions, and factor in TLABs if necessary. 303 304 // Addresses come in pairs. 305 List<Address> liveRegions = new ArrayList<>(); 306 LiveRegionsCollector lrc = new LiveRegionsCollector(liveRegions); 307 308 CollectedHeap heap = VM.getVM().getUniverse().heap(); 309 heap.liveRegionsIterate(lrc); 310 311 // If UseTLAB is enabled, snip out regions associated with TLABs' 312 // dead regions. Note that TLABs can be present in any generation. 313 314 // FIXME: consider adding fewer boundaries to live region list. 315 // Theoretically only need to stop at TLAB's top and resume at its 316 // end. 317 318 if (VM.getVM().getUseTLAB()) { 319 Threads threads = VM.getVM().getThreads(); 320 for (int i = 0; i < threads.getNumberOfThreads(); i++) { 321 JavaThread thread = threads.getJavaThreadAt(i); 322 ThreadLocalAllocBuffer tlab = thread.tlab(); 323 if (tlab.start() != null) { 324 if ((tlab.top() == null) || (tlab.end() == null)) { 325 System.err.print("Warning: skipping invalid TLAB for thread "); 326 thread.printThreadIDOn(System.err); 327 System.err.println(); 328 } else { 329 if (DEBUG) { 330 System.err.print("TLAB for " + thread.getThreadName() + ", #"); 331 thread.printThreadIDOn(System.err); 332 System.err.print(": "); 333 tlab.printOn(System.err); 334 } 335 // Go from: 336 // - below start() to start() 337 // - start() to top() 338 // - end() and above 339 liveRegions.add(tlab.start()); 340 liveRegions.add(tlab.start()); 341 liveRegions.add(tlab.top()); 342 liveRegions.add(tlab.hardEnd()); 343 } 344 } 345 } 346 } 347 348 // Now sort live regions 349 sortLiveRegions(liveRegions); 350 351 if (Assert.ASSERTS_ENABLED) { 352 Assert.that(liveRegions.size() % 2 == 0, "Must have even number of region boundaries"); 353 } 354 355 if (DEBUG) { 356 System.err.println("liveRegions:"); 357 for (int i = 0; i < liveRegions.size(); i += 2) { 358 Address bottom = (Address) liveRegions.get(i); 359 Address top = (Address) liveRegions.get(i+1); 360 System.err.println(" " + bottom + " - " + top); 361 } 362 } 363 364 return liveRegions; 365 } 366 sortLiveRegions(List<Address> liveRegions)367 private void sortLiveRegions(List<Address> liveRegions) { 368 Collections.sort(liveRegions, new Comparator<Address>() { 369 public int compare(Address a1, Address a2) { 370 if (AddressOps.lt(a1, a2)) { 371 return -1; 372 } else if (AddressOps.gt(a1, a2)) { 373 return 1; 374 } 375 return 0; 376 } 377 }); 378 } 379 } 380