30 // according to its name resolution strategy. 31 // 32 // Class loaders that implement a deterministic name resolution strategy 33 // (including with respect to their delegation behavior), such as the boot, the 34 // platform, and the system loaders of the JDK's built-in class loader 35 // hierarchy, always produce the same linkset for a given configuration. 36 // 37 // ClassLoaderData carries information related to a linkset (e.g., 38 // metaspace holding its klass definitions). 39 // The System Dictionary and related data structures (e.g., placeholder table, 40 // loader constraints table) as well as the runtime representation of classes 41 // only reference ClassLoaderData. 42 // 43 // Instances of java.lang.ClassLoader holds a pointer to a ClassLoaderData that 44 // that represent the loader's "linking domain" in the JVM. 45 // 46 // The bootstrap loader (represented by NULL) also has a ClassLoaderData, 47 // the singleton class the_null_class_loader_data(). 48 49 #include "precompiled.hpp" 50 #include "classfile/classLoaderData.hpp" 51 #include "classfile/classLoaderData.inline.hpp" 52 #include "classfile/dictionary.hpp" 53 #include "classfile/javaClasses.hpp" 54 #include "classfile/metadataOnStackMark.hpp" 55 #include "classfile/moduleEntry.hpp" 56 #include "classfile/packageEntry.hpp" 57 #include "classfile/systemDictionary.hpp" 58 #include "code/codeCache.hpp" 59 #include "gc/shared/gcLocker.hpp" 60 #include "logging/log.hpp" 61 #include "logging/logStream.hpp" 62 #include "memory/metadataFactory.hpp" 63 #include "memory/metaspaceShared.hpp" 64 #include "memory/oopFactory.hpp" 65 #include "memory/resourceArea.hpp" 66 #include "oops/objArrayOop.inline.hpp" 67 #include "oops/oop.inline.hpp" 68 #include "runtime/atomic.hpp" 69 #include "runtime/javaCalls.hpp" 70 #include "runtime/jniHandles.hpp" 71 #include "runtime/mutex.hpp" 72 #include "runtime/orderAccess.hpp" 73 #include "runtime/safepoint.hpp" 74 #include "runtime/synchronizer.hpp" 75 #include "utilities/growableArray.hpp" 76 #include "utilities/macros.hpp" 77 #include "utilities/ostream.hpp" 78 #if INCLUDE_ALL_GCS 79 #include "gc/g1/g1SATBCardTableModRefBS.hpp" 80 #endif // INCLUDE_ALL_GCS 81 #if INCLUDE_TRACE 82 #include "trace/tracing.hpp" 83 #endif 84 85 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL; 86 87 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous, Dependencies dependencies) : 88 _class_loader(h_class_loader()), 89 _is_anonymous(is_anonymous), 90 // An anonymous class loader data doesn't have anything to keep 91 // it from being unloaded during parsing of the anonymous class. 92 // The null-class-loader should always be kept alive. 93 _keep_alive((is_anonymous || h_class_loader.is_null()) ? 1 : 0), 94 _metaspace(NULL), _unloading(false), _klasses(NULL), 95 _modules(NULL), _packages(NULL), 96 _claimed(0), _modified_oops(true), _accumulated_modified_oops(false), 97 _jmethod_ids(NULL), _handles(), _deallocate_list(NULL), 98 _next(NULL), _dependencies(dependencies), 99 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true, 100 Monitor::_safepoint_check_never)) { 101 102 // A ClassLoaderData created solely for an anonymous class should never have a 103 // ModuleEntryTable or PackageEntryTable created for it. The defining package 104 // and module for an anonymous class will be found in its host class. 105 if (!is_anonymous) { 106 _packages = new PackageEntryTable(PackageEntryTable::_packagetable_entry_size); 107 if (h_class_loader.is_null()) { 108 // Create unnamed module for boot loader 109 _unnamed_module = ModuleEntry::create_boot_unnamed_module(this); 110 } else { 111 // Create unnamed module for all other loaders 112 _unnamed_module = ModuleEntry::create_unnamed_module(this); 113 } 114 } else { 115 _unnamed_module = NULL; 116 } 117 118 if (!is_anonymous) { 119 _dictionary = create_dictionary(); 120 } else { 121 _dictionary = NULL; 122 } 123 TRACE_INIT_ID(this); 124 } 125 126 void ClassLoaderData::init_dependencies(TRAPS) { 127 assert(!Universe::is_fully_initialized(), "should only be called when initializing"); 128 assert(is_the_null_class_loader_data(), "should only call this for the null class loader"); 129 _dependencies.init(CHECK); 130 } 131 132 void ClassLoaderData::Dependencies::init(TRAPS) { 133 // Create empty dependencies array to add to. CMS requires this to be 134 // an oop so that it can track additions via card marks. We think. 135 _list_head = oopFactory::new_objectArray(2, CHECK); 136 } 137 138 ClassLoaderData::ChunkedHandleList::~ChunkedHandleList() { 139 Chunk* c = _head; 140 while (c != NULL) { 141 Chunk* next = c->_next; 142 delete c; 143 c = next; 144 } 145 } 146 147 oop* ClassLoaderData::ChunkedHandleList::add(oop o) { 148 if (_head == NULL || _head->_size == Chunk::CAPACITY) { 149 Chunk* next = new Chunk(_head); 150 OrderAccess::release_store(&_head, next); 151 } 152 oop* handle = &_head->_data[_head->_size]; 153 *handle = o; 154 OrderAccess::release_store(&_head->_size, _head->_size + 1); 155 return handle; 156 } 157 158 inline void ClassLoaderData::ChunkedHandleList::oops_do_chunk(OopClosure* f, Chunk* c, const juint size) { 159 for (juint i = 0; i < size; i++) { 160 if (c->_data[i] != NULL) { 161 f->do_oop(&c->_data[i]); 162 } 163 } 164 } 165 166 void ClassLoaderData::ChunkedHandleList::oops_do(OopClosure* f) { 167 Chunk* head = OrderAccess::load_acquire(&_head); 168 if (head != NULL) { 169 // Must be careful when reading size of head 170 oops_do_chunk(f, head, OrderAccess::load_acquire(&head->_size)); 171 for (Chunk* c = head->_next; c != NULL; c = c->_next) { 172 oops_do_chunk(f, c, c->_size); 173 } 174 } 175 } 176 177 #ifdef ASSERT 178 class VerifyContainsOopClosure : public OopClosure { 179 oop* _target; 180 bool _found; 181 182 public: 183 VerifyContainsOopClosure(oop* target) : _target(target), _found(false) {} 184 185 void do_oop(oop* p) { 186 if (p == _target) { 187 _found = true; 188 } 189 } 190 191 void do_oop(narrowOop* p) { 192 // The ChunkedHandleList should not contain any narrowOop 193 ShouldNotReachHere(); 194 } 195 196 bool found() const { 197 return _found; 198 } 199 }; 200 201 bool ClassLoaderData::ChunkedHandleList::contains(oop* p) { 202 VerifyContainsOopClosure cl(p); 203 oops_do(&cl); 204 return cl.found(); 205 } 206 #endif // ASSERT 207 208 bool ClassLoaderData::claim() { 209 if (_claimed == 1) { 210 return false; 211 } 212 213 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0; 214 } 215 216 // Anonymous classes have their own ClassLoaderData that is marked to keep alive 217 // while the class is being parsed, and if the class appears on the module fixup list. 218 // Due to the uniqueness that no other class shares the anonymous class' name or 219 // ClassLoaderData, no other non-GC thread has knowledge of the anonymous class while 220 // it is being defined, therefore _keep_alive is not volatile or atomic. 221 void ClassLoaderData::inc_keep_alive() { 222 if (is_anonymous()) { 223 assert(_keep_alive >= 0, "Invalid keep alive increment count"); 224 _keep_alive++; 225 } 226 } 227 228 void ClassLoaderData::dec_keep_alive() { 229 if (is_anonymous()) { 230 assert(_keep_alive > 0, "Invalid keep alive decrement count"); 231 _keep_alive--; 232 } 233 } 234 235 void ClassLoaderData::oops_do(OopClosure* f, bool must_claim, bool clear_mod_oops) { 236 if (must_claim && !claim()) { 237 return; 238 } 239 240 // Only clear modified_oops after the ClassLoaderData is claimed. 241 if (clear_mod_oops) { 242 clear_modified_oops(); 243 } 244 245 f->do_oop(&_class_loader); 246 _dependencies.oops_do(f); 247 _handles.oops_do(f); 248 } 249 250 void ClassLoaderData::Dependencies::oops_do(OopClosure* f) { 251 f->do_oop((oop*)&_list_head); 252 } 253 254 void ClassLoaderData::classes_do(KlassClosure* klass_closure) { 255 // Lock-free access requires load_acquire 256 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 257 klass_closure->do_klass(k); 258 assert(k != k->next_link(), "no loops!"); 259 } 260 } 261 262 void ClassLoaderData::classes_do(void f(Klass * const)) { 263 // Lock-free access requires load_acquire 264 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 265 f(k); 266 assert(k != k->next_link(), "no loops!"); 267 } 268 } 269 270 void ClassLoaderData::methods_do(void f(Method*)) { 271 // Lock-free access requires load_acquire 272 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 273 if (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded()) { 274 InstanceKlass::cast(k)->methods_do(f); 275 } 276 } 277 } 278 279 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) { 280 // Lock-free access requires load_acquire 281 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 282 // Do not filter ArrayKlass oops here... 283 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) { 284 klass_closure->do_klass(k); 285 } 286 } 287 } 288 289 void ClassLoaderData::classes_do(void f(InstanceKlass*)) { 290 // Lock-free access requires load_acquire 291 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 292 if (k->is_instance_klass()) { 293 f(InstanceKlass::cast(k)); 294 } 295 assert(k != k->next_link(), "no loops!"); 296 } 297 } 298 299 void ClassLoaderData::modules_do(void f(ModuleEntry*)) { 300 assert_locked_or_safepoint(Module_lock); 301 if (_unnamed_module != NULL) { 302 f(_unnamed_module); 303 } 304 if (_modules != NULL) { 305 for (int i = 0; i < _modules->table_size(); i++) { 306 for (ModuleEntry* entry = _modules->bucket(i); 307 entry != NULL; 308 entry = entry->next()) { 309 f(entry); 310 } 311 } 312 } 313 } 314 315 void ClassLoaderData::packages_do(void f(PackageEntry*)) { 316 assert_locked_or_safepoint(Module_lock); 317 if (_packages != NULL) { 318 for (int i = 0; i < _packages->table_size(); i++) { 319 for (PackageEntry* entry = _packages->bucket(i); 320 entry != NULL; 321 entry = entry->next()) { 322 f(entry); 323 } 324 } 325 } 326 } 327 328 void ClassLoaderData::record_dependency(const Klass* k, TRAPS) { 329 assert(k != NULL, "invariant"); 330 331 ClassLoaderData * const from_cld = this; 332 ClassLoaderData * const to_cld = k->class_loader_data(); 333 334 // Dependency to the null class loader data doesn't need to be recorded 335 // because the null class loader data never goes away. 336 if (to_cld->is_the_null_class_loader_data()) { 337 return; 338 } 339 340 oop to; 341 if (to_cld->is_anonymous()) { 342 // Anonymous class dependencies are through the mirror. 343 to = k->java_mirror(); 344 } else { 345 to = to_cld->class_loader(); 346 347 // If from_cld is anonymous, even if it's class_loader is a parent of 'to' 348 // we still have to add it. The class_loader won't keep from_cld alive. 349 if (!from_cld->is_anonymous()) { 350 // Check that this dependency isn't from the same or parent class_loader 351 oop from = from_cld->class_loader(); 352 353 oop curr = from; 354 while (curr != NULL) { 355 if (curr == to) { 356 return; // this class loader is in the parent list, no need to add it. 357 } 358 curr = java_lang_ClassLoader::parent(curr); 359 } 360 } 361 } 362 363 // It's a dependency we won't find through GC, add it. This is relatively rare 364 // Must handle over GC point. 365 Handle dependency(THREAD, to); 366 from_cld->_dependencies.add(dependency, CHECK); 367 368 // Added a potentially young gen oop to the ClassLoaderData 369 record_modified_oops(); 370 } 371 372 373 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) { 374 // Check first if this dependency is already in the list. 375 // Save a pointer to the last to add to under the lock. 376 objArrayOop ok = _list_head; 377 objArrayOop last = NULL; 378 while (ok != NULL) { 379 last = ok; 380 if (ok->obj_at(0) == dependency()) { 381 // Don't need to add it 382 return; 383 } 384 ok = (objArrayOop)ok->obj_at(1); 385 } 386 387 // Must handle over GC points 388 assert (last != NULL, "dependencies should be initialized"); 389 objArrayHandle last_handle(THREAD, last); 390 391 // Create a new dependency node with fields for (class_loader or mirror, next) 392 objArrayOop deps = oopFactory::new_objectArray(2, CHECK); 393 deps->obj_at_put(0, dependency()); 394 395 // Must handle over GC points 396 objArrayHandle new_dependency(THREAD, deps); 397 398 // Add the dependency under lock 399 locked_add(last_handle, new_dependency, THREAD); 400 } 401 402 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle, 403 objArrayHandle new_dependency, 404 Thread* THREAD) { 405 406 // Have to lock and put the new dependency on the end of the dependency 407 // array so the card mark for CMS sees that this dependency is new. 408 // Can probably do this lock free with some effort. 409 ObjectLocker ol(Handle(THREAD, _list_head), THREAD); 410 411 oop loader_or_mirror = new_dependency->obj_at(0); 412 413 // Since the dependencies are only added, add to the end. 414 objArrayOop end = last_handle(); 415 objArrayOop last = NULL; 416 while (end != NULL) { 417 last = end; 418 // check again if another thread added it to the end. 419 if (end->obj_at(0) == loader_or_mirror) { 420 // Don't need to add it 421 return; 422 } 423 end = (objArrayOop)end->obj_at(1); 424 } 425 assert (last != NULL, "dependencies should be initialized"); 426 // fill in the first element with the oop in new_dependency. 427 if (last->obj_at(0) == NULL) { 428 last->obj_at_put(0, new_dependency->obj_at(0)); 429 } else { 430 last->obj_at_put(1, new_dependency()); 431 } 432 } 433 434 void ClassLoaderDataGraph::clear_claimed_marks() { 435 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 436 cld->clear_claimed(); 437 } 438 } 439 440 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) { 441 { 442 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 443 Klass* old_value = _klasses; 444 k->set_next_link(old_value); 445 // Link the new item into the list, making sure the linked class is stable 446 // since the list can be walked without a lock 447 OrderAccess::release_store(&_klasses, k); 448 } 449 450 if (publicize && k->class_loader_data() != NULL) { 451 ResourceMark rm; 452 log_trace(class, loader, data)("Adding k: " PTR_FORMAT " %s to CLD: " 453 PTR_FORMAT " loader: " PTR_FORMAT " %s", 454 p2i(k), 455 k->external_name(), 456 p2i(k->class_loader_data()), 457 p2i((void *)k->class_loader()), 458 loader_name()); 459 } 460 } 461 462 // Class iterator used by the compiler. It gets some number of classes at 463 // a safepoint to decay invocation counters on the methods. 464 class ClassLoaderDataGraphKlassIteratorStatic { 465 ClassLoaderData* _current_loader_data; 466 Klass* _current_class_entry; 467 public: 468 469 ClassLoaderDataGraphKlassIteratorStatic() : _current_loader_data(NULL), _current_class_entry(NULL) {} 470 471 InstanceKlass* try_get_next_class() { 472 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 473 int max_classes = InstanceKlass::number_of_instance_classes(); 474 assert(max_classes > 0, "should not be called with no instance classes"); 475 for (int i = 0; i < max_classes; ) { 476 477 if (_current_class_entry != NULL) { 478 Klass* k = _current_class_entry; 479 _current_class_entry = _current_class_entry->next_link(); 480 481 if (k->is_instance_klass()) { 482 InstanceKlass* ik = InstanceKlass::cast(k); 483 i++; // count all instance classes found 484 // Not yet loaded classes are counted in max_classes 485 // but only return loaded classes. 486 if (ik->is_loaded()) { 487 return ik; 488 } 489 } 504 // Caller handles NULL. 505 return NULL; 506 } 507 508 // If the current class for the static iterator is a class being unloaded or 509 // deallocated, adjust the current class. 510 void adjust_saved_class(ClassLoaderData* cld) { 511 if (_current_loader_data == cld) { 512 _current_loader_data = cld->next(); 513 if (_current_loader_data != NULL) { 514 _current_class_entry = _current_loader_data->klasses(); 515 } // else try_get_next_class will start at the head 516 } 517 } 518 519 void adjust_saved_class(Klass* klass) { 520 if (_current_class_entry == klass) { 521 _current_class_entry = klass->next_link(); 522 } 523 } 524 }; 525 526 static ClassLoaderDataGraphKlassIteratorStatic static_klass_iterator; 527 528 InstanceKlass* ClassLoaderDataGraph::try_get_next_class() { 529 return static_klass_iterator.try_get_next_class(); 530 } 531 532 533 // Remove a klass from the _klasses list for scratch_class during redefinition 534 // or parsed class in the case of an error. 535 void ClassLoaderData::remove_class(Klass* scratch_class) { 536 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 537 538 // Adjust global class iterator. 539 static_klass_iterator.adjust_saved_class(scratch_class); 540 541 Klass* prev = NULL; 542 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 543 if (k == scratch_class) { 544 if (prev == NULL) { 545 _klasses = k->next_link(); 546 } else { 547 Klass* next = k->next_link(); 548 prev->set_next_link(next); 549 } 550 return; 551 } 552 prev = k; 553 assert(k != k->next_link(), "no loops!"); 554 } 555 ShouldNotReachHere(); // should have found this class!! 556 } 557 558 void ClassLoaderData::unload() { 559 _unloading = true; 560 561 // Tell serviceability tools these classes are unloading 562 classes_do(InstanceKlass::notify_unload_class); 563 564 LogTarget(Debug, class, loader, data) lt; 565 if (lt.is_enabled()) { 566 ResourceMark rm; 567 LogStream ls(lt); 568 ls.print(": unload loader data " INTPTR_FORMAT, p2i(this)); 569 ls.print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()), 570 loader_name()); 571 if (is_anonymous()) { 572 ls.print(" for anonymous class " INTPTR_FORMAT " ", p2i(_klasses)); 573 } 574 ls.cr(); 575 } 576 577 // Some items on the _deallocate_list need to free their C heap structures 578 // if they are not already on the _klasses list. 579 unload_deallocate_list(); 580 581 // Clean up global class iterator for compiler 582 static_klass_iterator.adjust_saved_class(this); 583 } 584 585 ModuleEntryTable* ClassLoaderData::modules() { 586 // Lazily create the module entry table at first request. 587 // Lock-free access requires load_acquire. 588 ModuleEntryTable* modules = OrderAccess::load_acquire(&_modules); 589 if (modules == NULL) { 590 MutexLocker m1(Module_lock); 591 // Check if _modules got allocated while we were waiting for this lock. 592 if ((modules = _modules) == NULL) { 593 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size); 594 595 { 596 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag); 597 // Ensure _modules is stable, since it is examined without a lock 598 OrderAccess::release_store(&_modules, modules); 599 } 600 } 601 } 602 return modules; 603 } 604 605 const int _boot_loader_dictionary_size = 1009; 606 const int _default_loader_dictionary_size = 107; 607 608 Dictionary* ClassLoaderData::create_dictionary() { 609 assert(!is_anonymous(), "anonymous class loader data do not have a dictionary"); 610 int size; 611 bool resizable = false; 612 if (_the_null_class_loader_data == NULL) { 613 size = _boot_loader_dictionary_size; 614 resizable = true; 615 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) { 616 size = 1; // there's only one class in relection class loader and no initiated classes 617 } else if (is_system_class_loader_data()) { 618 size = _boot_loader_dictionary_size; 619 resizable = true; 620 } else { 621 size = _default_loader_dictionary_size; 622 resizable = true; 623 } 624 if (!DynamicallyResizeSystemDictionaries || DumpSharedSpaces || UseSharedSpaces) { 625 resizable = false; 626 } 627 return new Dictionary(this, size, resizable); 628 } 629 630 // Unloading support 631 oop ClassLoaderData::keep_alive_object() const { 632 assert_locked_or_safepoint(_metaspace_lock); 633 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive"); 634 return is_anonymous() ? _klasses->java_mirror() : class_loader(); 635 } 636 637 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const { 638 bool alive = keep_alive() // null class loader and incomplete anonymous klasses. 639 || is_alive_closure->do_object_b(keep_alive_object()); 640 641 return alive; 642 } 643 644 ClassLoaderData::~ClassLoaderData() { 645 // Release C heap structures for all the classes. 646 classes_do(InstanceKlass::release_C_heap_structures); 647 648 // Release C heap allocated hashtable for all the packages. 649 if (_packages != NULL) { 650 // Destroy the table itself 651 delete _packages; 652 _packages = NULL; 653 } 654 655 // Release C heap allocated hashtable for all the modules. 656 if (_modules != NULL) { 657 // Destroy the table itself 658 delete _modules; 659 _modules = NULL; 660 } 661 662 // Release C heap allocated hashtable for the dictionary 663 if (_dictionary != NULL) { 664 // Destroy the table itself 665 delete _dictionary; 666 _dictionary = NULL; 667 } 668 669 if (_unnamed_module != NULL) { 670 _unnamed_module->delete_unnamed_module(); 671 _unnamed_module = NULL; 672 } 673 674 // release the metaspace 675 Metaspace *m = _metaspace; 676 if (m != NULL) { 677 _metaspace = NULL; 678 delete m; 679 } 680 // Clear all the JNI handles for methods 681 // These aren't deallocated and are going to look like a leak, but that's 682 // needed because we can't really get rid of jmethodIDs because we don't 683 // know when native code is going to stop using them. The spec says that 684 // they're "invalid" but existing programs likely rely on their being 685 // NULL after class unloading. 686 if (_jmethod_ids != NULL) { 687 Method::clear_jmethod_ids(this); 688 } 689 // Delete lock 690 delete _metaspace_lock; 691 692 // Delete free list 693 if (_deallocate_list != NULL) { 694 delete _deallocate_list; 695 } 696 } 697 698 // Returns true if this class loader data is for the system class loader. 699 bool ClassLoaderData::is_system_class_loader_data() const { 700 return SystemDictionary::is_system_class_loader(class_loader()); 701 } 702 703 // Returns true if this class loader data is for the platform class loader. 704 bool ClassLoaderData::is_platform_class_loader_data() const { 705 return SystemDictionary::is_platform_class_loader(class_loader()); 706 } 707 708 // Returns true if this class loader data is one of the 3 builtin 709 // (boot, application/system or platform) class loaders. Note, the 710 // builtin loaders are not freed by a GC. 711 bool ClassLoaderData::is_builtin_class_loader_data() const { 712 return (is_the_null_class_loader_data() || 713 SystemDictionary::is_system_class_loader(class_loader()) || 714 SystemDictionary::is_platform_class_loader(class_loader())); 715 } 716 717 Metaspace* ClassLoaderData::metaspace_non_null() { 718 // If the metaspace has not been allocated, create a new one. Might want 719 // to create smaller arena for Reflection class loaders also. 720 // The reason for the delayed allocation is because some class loaders are 721 // simply for delegating with no metadata of their own. 722 // Lock-free access requires load_acquire. 723 Metaspace* metaspace = OrderAccess::load_acquire(&_metaspace); 724 if (metaspace == NULL) { 725 MutexLockerEx ml(_metaspace_lock, Mutex::_no_safepoint_check_flag); 726 // Check if _metaspace got allocated while we were waiting for this lock. 727 if ((metaspace = _metaspace) == NULL) { 728 if (this == the_null_class_loader_data()) { 729 assert (class_loader() == NULL, "Must be"); 730 metaspace = new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType); 731 } else if (is_anonymous()) { 732 if (class_loader() != NULL) { 733 log_trace(class, loader, data)("is_anonymous: %s", class_loader()->klass()->internal_name()); 734 } 735 metaspace = new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType); 736 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) { 737 if (class_loader() != NULL) { 738 log_trace(class, loader, data)("is_reflection: %s", class_loader()->klass()->internal_name()); 739 } 740 metaspace = new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType); 741 } else { 742 metaspace = new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType); 743 } 744 // Ensure _metaspace is stable, since it is examined without a lock 745 OrderAccess::release_store(&_metaspace, metaspace); 746 } 747 } 748 return metaspace; 749 } 750 751 OopHandle ClassLoaderData::add_handle(Handle h) { 752 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 753 record_modified_oops(); 754 return OopHandle(_handles.add(h())); 755 } 756 757 void ClassLoaderData::remove_handle(OopHandle h) { 758 assert(!is_unloading(), "Do not remove a handle for a CLD that is unloading"); 759 oop* ptr = h.ptr_raw(); 760 if (ptr != NULL) { 761 assert(_handles.contains(ptr), "Got unexpected handle " PTR_FORMAT, p2i(ptr)); 762 #if INCLUDE_ALL_GCS 763 // This barrier is used by G1 to remember the old oop values, so 764 // that we don't forget any objects that were live at the snapshot at 765 // the beginning. 766 if (UseG1GC) { 767 oop obj = *ptr; 768 if (obj != NULL) { 769 G1SATBCardTableModRefBS::enqueue(obj); 770 } 771 } 772 #endif 773 *ptr = NULL; 774 } 775 } 776 777 void ClassLoaderData::init_handle_locked(OopHandle& dest, Handle h) { 778 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 779 if (dest.resolve() != NULL) { 780 return; 781 } else { 782 dest = _handles.add(h()); 783 } 784 } 785 786 // Add this metadata pointer to be freed when it's safe. This is only during 787 // class unloading because Handles might point to this metadata field. 788 void ClassLoaderData::add_to_deallocate_list(Metadata* m) { 789 // Metadata in shared region isn't deleted. 790 if (!m->is_shared()) { 791 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 792 if (_deallocate_list == NULL) { 793 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true); 794 } 795 _deallocate_list->append_if_missing(m); 796 } 797 } 798 799 // Deallocate free metadata on the free list. How useful the PermGen was! 800 void ClassLoaderData::free_deallocate_list() { 801 // Don't need lock, at safepoint 802 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 803 assert(!is_unloading(), "only called for ClassLoaderData that are not unloading"); 804 if (_deallocate_list == NULL) { 805 return; 806 } 807 // Go backwards because this removes entries that are freed. 808 for (int i = _deallocate_list->length() - 1; i >= 0; i--) { 809 Metadata* m = _deallocate_list->at(i); 810 if (!m->on_stack()) { 811 _deallocate_list->remove_at(i); 812 // There are only three types of metadata that we deallocate directly. 813 // Cast them so they can be used by the template function. 814 if (m->is_method()) { 815 MetadataFactory::free_metadata(this, (Method*)m); 816 } else if (m->is_constantPool()) { 817 MetadataFactory::free_metadata(this, (ConstantPool*)m); 818 } else if (m->is_klass()) { 819 MetadataFactory::free_metadata(this, (InstanceKlass*)m); 820 } else { 821 ShouldNotReachHere(); 822 } 823 } else { 824 // Metadata is alive. 825 // If scratch_class is on stack then it shouldn't be on this list! 826 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(), 827 "scratch classes on this list should be dead"); 828 // Also should assert that other metadata on the list was found in handles. 829 } 830 } 831 } 832 833 // This is distinct from free_deallocate_list. For class loader data that are 834 // unloading, this frees the C heap memory for constant pools on the list. If there 835 // were C heap memory allocated for methods, it would free that too. The C heap memory 836 // for InstanceKlasses on this list is freed in the ClassLoaderData destructor. 837 void ClassLoaderData::unload_deallocate_list() { 838 // Don't need lock, at safepoint 839 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 840 assert(is_unloading(), "only called for ClassLoaderData that are unloading"); 841 if (_deallocate_list == NULL) { 842 return; 843 } 844 // Go backwards because this removes entries that are freed. 845 for (int i = _deallocate_list->length() - 1; i >= 0; i--) { 846 Metadata* m = _deallocate_list->at(i); 847 assert (!m->on_stack(), "wouldn't be unloading if this were so"); 848 _deallocate_list->remove_at(i); 849 // Only constant pool entries have C heap memory to free. 850 if (m->is_constantPool()) { 851 ((ConstantPool*)m)->release_C_heap_structures(); 852 } 853 } 854 } 855 856 // These anonymous class loaders are to contain classes used for JSR292 857 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) { 858 // Add a new class loader data to the graph. 859 Handle lh(THREAD, loader); 860 return ClassLoaderDataGraph::add(lh, true, THREAD); 861 } 862 863 const char* ClassLoaderData::loader_name() { 864 // Handles null class loader 865 return SystemDictionary::loader_name(class_loader()); 866 } 867 868 #ifndef PRODUCT 869 // Define to dump klasses 870 #undef CLD_DUMP_KLASSES 871 872 void ClassLoaderData::dump(outputStream * const out) { 873 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: " PTR_FORMAT " %s {", 874 p2i(this), p2i((void *)class_loader()), 875 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name()); 876 if (claimed()) out->print(" claimed "); 877 if (is_unloading()) out->print(" unloading "); 878 out->cr(); 879 if (metaspace_or_null() != NULL) { 880 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null())); 881 metaspace_or_null()->dump(out); 882 } else { 883 out->print_cr("metaspace: NULL"); 884 } 885 886 #ifdef CLD_DUMP_KLASSES 887 if (Verbose) { 888 Klass* k = _klasses; 889 while (k != NULL) { 890 out->print_cr("klass " PTR_FORMAT ", %s", p2i(k), k->name()->as_C_string()); 891 assert(k != k->next_link(), "no loops!"); 892 k = k->next_link(); 893 } 894 } 895 #endif // CLD_DUMP_KLASSES 896 #undef CLD_DUMP_KLASSES 897 if (_jmethod_ids != NULL) { 898 Method::print_jmethod_ids(this, out); 899 } 900 out->print_cr("}"); 901 } 902 #endif // PRODUCT 903 904 void ClassLoaderData::verify() { 905 assert_locked_or_safepoint(_metaspace_lock); 906 oop cl = class_loader(); 907 908 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same"); 909 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be"); 910 911 // Verify the integrity of the allocated space. 912 if (metaspace_or_null() != NULL) { 913 metaspace_or_null()->verify(); 914 } 915 916 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 917 guarantee(k->class_loader_data() == this, "Must be the same"); 918 k->verify(); 919 assert(k != k->next_link(), "no loops!"); 920 } 921 } 922 923 bool ClassLoaderData::contains_klass(Klass* klass) { 924 // Lock-free access requires load_acquire 925 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 926 if (k == klass) return true; 927 } 928 return false; 929 } 930 931 932 // GC root of class loader data created. 933 ClassLoaderData* ClassLoaderDataGraph::_head = NULL; 934 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL; 935 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL; 936 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL; 937 938 bool ClassLoaderDataGraph::_should_purge = false; 939 bool ClassLoaderDataGraph::_metaspace_oom = false; 940 941 // Add a new class loader data node to the list. Assign the newly created 942 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field 943 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) { 944 // We need to allocate all the oops for the ClassLoaderData before allocating the 945 // actual ClassLoaderData object. 946 ClassLoaderData::Dependencies dependencies(CHECK_NULL); 947 948 NoSafepointVerifier no_safepoints; // we mustn't GC until we've installed the 949 // ClassLoaderData in the graph since the CLD 950 // contains unhandled oops 951 952 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies); 953 954 955 if (!is_anonymous) { 956 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader()); 957 // First, Atomically set it 958 ClassLoaderData* old = Atomic::cmpxchg(cld, cld_addr, (ClassLoaderData*)NULL); 959 if (old != NULL) { 960 delete cld; 967 // class loader data 968 ClassLoaderData** list_head = &_head; 969 ClassLoaderData* next = _head; 970 971 do { 972 cld->set_next(next); 973 ClassLoaderData* exchanged = Atomic::cmpxchg(cld, list_head, next); 974 if (exchanged == next) { 975 LogTarget(Debug, class, loader, data) lt; 976 if (lt.is_enabled()) { 977 PauseNoSafepointVerifier pnsv(&no_safepoints); // Need safe points for JavaCalls::call_virtual 978 LogStream ls(lt); 979 print_creation(&ls, loader, cld, CHECK_NULL); 980 } 981 return cld; 982 } 983 next = exchanged; 984 } while (true); 985 } 986 987 void ClassLoaderDataGraph::print_creation(outputStream* out, Handle loader, ClassLoaderData* cld, TRAPS) { 988 Handle string; 989 if (loader.not_null()) { 990 // Include the result of loader.toString() in the output. This allows 991 // the user of the log to identify the class loader instance. 992 JavaValue result(T_OBJECT); 993 Klass* spec_klass = SystemDictionary::ClassLoader_klass(); 994 JavaCalls::call_virtual(&result, 995 loader, 996 spec_klass, 997 vmSymbols::toString_name(), 998 vmSymbols::void_string_signature(), 999 CHECK); 1000 assert(result.get_type() == T_OBJECT, "just checking"); 1001 string = Handle(THREAD, (oop)result.get_jobject()); 1002 } 1003 1004 ResourceMark rm; 1005 out->print("create class loader data " INTPTR_FORMAT, p2i(cld)); 1006 out->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()), 1007 cld->loader_name()); 1008 1009 if (string.not_null()) { 1010 out->print(": "); 1011 java_lang_String::print(string(), out); 1012 } 1013 out->cr(); 1014 } 1015 1016 1017 void ClassLoaderDataGraph::oops_do(OopClosure* f, bool must_claim) { 1018 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 1019 cld->oops_do(f, must_claim); 1020 } 1021 } 1022 1023 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, bool must_claim) { 1024 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 1025 if (cld->keep_alive()) { 1026 cld->oops_do(f, must_claim); 1027 } 1028 } 1029 } 1030 1031 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, bool must_claim) { 1032 if (ClassUnloading) { 1033 keep_alive_oops_do(f, must_claim); 1034 } else { 1035 oops_do(f, must_claim); 1036 } 1209 ls.cr(); 1210 } 1211 } 1212 1213 curr = curr->_next; 1214 } 1215 1216 return array; 1217 } 1218 1219 bool ClassLoaderDataGraph::unload_list_contains(const void* x) { 1220 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint"); 1221 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) { 1222 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) { 1223 return true; 1224 } 1225 } 1226 return false; 1227 } 1228 1229 #ifndef PRODUCT 1230 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) { 1231 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 1232 if (loader_data == data) { 1233 return true; 1234 } 1235 } 1236 1237 return false; 1238 } 1239 #endif // PRODUCT 1240 1241 1242 // Move class loader data from main list to the unloaded list for unloading 1243 // and deallocation later. 1244 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure, 1245 bool clean_previous_versions) { 1246 1247 ClassLoaderData* data = _head; 1248 ClassLoaderData* prev = NULL; 1249 bool seen_dead_loader = false; 1250 1251 // Mark metadata seen on the stack only so we can delete unneeded entries. 1252 // Only walk all metadata, including the expensive code cache walk, for Full GC 1253 // and only if class redefinition and if there's previous versions of 1254 // Klasses to delete. 1255 bool walk_all_metadata = clean_previous_versions && 1256 JvmtiExport::has_redefined_a_class() && 1257 InstanceKlass::has_previous_versions_and_reset(); 1258 MetadataOnStackMark md_on_stack(walk_all_metadata); 1259 1260 // Save previous _unloading pointer for CMS which may add to unloading list before 1320 } 1321 1322 void ClassLoaderDataGraph::purge() { 1323 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 1324 ClassLoaderData* list = _unloading; 1325 _unloading = NULL; 1326 ClassLoaderData* next = list; 1327 bool classes_unloaded = false; 1328 while (next != NULL) { 1329 ClassLoaderData* purge_me = next; 1330 next = purge_me->next(); 1331 delete purge_me; 1332 classes_unloaded = true; 1333 } 1334 if (classes_unloaded) { 1335 Metaspace::purge(); 1336 set_metaspace_oom(false); 1337 } 1338 } 1339 1340 int ClassLoaderDataGraph::resize_if_needed() { 1341 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 1342 int resized = 0; 1343 if (Dictionary::does_any_dictionary_needs_resizing()) { 1344 FOR_ALL_DICTIONARY(cld) { 1345 if (cld->dictionary()->resize_if_needed()) { 1346 resized++; 1347 } 1348 } 1349 } 1350 return resized; 1351 } 1352 1353 void ClassLoaderDataGraph::post_class_unload_events() { 1354 #if INCLUDE_TRACE 1355 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 1356 if (Tracing::enabled()) { 1357 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) { 1358 assert(_unloading != NULL, "need class loader data unload list!"); 1359 _class_unload_time = Ticks::now(); 1360 classes_unloading_do(&class_unload_event); 1361 } 1362 Tracing::on_unloading_classes(); 1363 } 1364 #endif 1365 } 1366 1367 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic() 1368 : _next_klass(NULL) { 1369 ClassLoaderData* cld = ClassLoaderDataGraph::_head; 1370 Klass* klass = NULL; 1371 1372 // Find the first klass in the CLDG. 1373 while (cld != NULL) { 1374 assert_locked_or_safepoint(cld->metaspace_lock()); 1375 klass = cld->_klasses; 1376 if (klass != NULL) { 1377 _next_klass = klass; 1378 return; 1379 } 1380 cld = cld->next(); 1381 } 1382 } 1383 1384 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) { 1385 Klass* next = klass->next_link(); 1386 if (next != NULL) { 1404 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() { 1405 Klass* head = _next_klass; 1406 1407 while (head != NULL) { 1408 Klass* next = next_klass_in_cldg(head); 1409 1410 Klass* old_head = Atomic::cmpxchg(next, &_next_klass, head); 1411 1412 if (old_head == head) { 1413 return head; // Won the CAS. 1414 } 1415 1416 head = old_head; 1417 } 1418 1419 // Nothing more for the iterator to hand out. 1420 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head)); 1421 return NULL; 1422 } 1423 1424 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() { 1425 _data = ClassLoaderDataGraph::_head; 1426 } 1427 1428 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {} 1429 1430 #ifndef PRODUCT 1431 // callable from debugger 1432 extern "C" int print_loader_data_graph() { 1433 ClassLoaderDataGraph::dump_on(tty); 1434 return 0; 1435 } 1436 1437 void ClassLoaderDataGraph::verify() { 1438 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 1439 data->verify(); 1440 } 1441 } 1442 1443 void ClassLoaderDataGraph::dump_on(outputStream * const out) { 1444 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 1445 data->dump(out); 1446 } 1447 MetaspaceAux::dump(out); 1448 } 1449 #endif // PRODUCT 1450 1451 void ClassLoaderData::print_value_on(outputStream* out) const { 1452 if (class_loader() == NULL) { 1453 out->print("NULL class loader"); 1454 } else { 1455 out->print("class loader " INTPTR_FORMAT " ", p2i(this)); 1456 class_loader()->print_value_on(out); 1457 } 1458 } 1459 1460 void ClassLoaderData::print_on(outputStream* out) const { 1461 if (class_loader() == NULL) { 1462 out->print("NULL class loader"); 1463 } else { 1464 out->print("class loader " INTPTR_FORMAT " ", p2i(this)); 1465 class_loader()->print_on(out); 1466 } 1467 } 1468 1469 #if INCLUDE_TRACE 1470 1471 Ticks ClassLoaderDataGraph::_class_unload_time; 1472 1473 void ClassLoaderDataGraph::class_unload_event(Klass* const k) { 1474 assert(k != NULL, "invariant"); 1475 1476 // post class unload event 1477 EventClassUnload event(UNTIMED); 1478 event.set_endtime(_class_unload_time); 1479 event.set_unloadedClass(k); 1480 event.set_definingClassLoader(k->class_loader_data()); 1481 event.commit(); 1482 } 1483 1484 #endif // INCLUDE_TRACE | 30 // according to its name resolution strategy. 31 // 32 // Class loaders that implement a deterministic name resolution strategy 33 // (including with respect to their delegation behavior), such as the boot, the 34 // platform, and the system loaders of the JDK's built-in class loader 35 // hierarchy, always produce the same linkset for a given configuration. 36 // 37 // ClassLoaderData carries information related to a linkset (e.g., 38 // metaspace holding its klass definitions). 39 // The System Dictionary and related data structures (e.g., placeholder table, 40 // loader constraints table) as well as the runtime representation of classes 41 // only reference ClassLoaderData. 42 // 43 // Instances of java.lang.ClassLoader holds a pointer to a ClassLoaderData that 44 // that represent the loader's "linking domain" in the JVM. 45 // 46 // The bootstrap loader (represented by NULL) also has a ClassLoaderData, 47 // the singleton class the_null_class_loader_data(). 48 49 #include "precompiled.hpp" 50 #include "classfile/classLoaderData.inline.hpp" 51 #include "classfile/dictionary.hpp" 52 #include "classfile/javaClasses.hpp" 53 #include "classfile/metadataOnStackMark.hpp" 54 #include "classfile/moduleEntry.hpp" 55 #include "classfile/packageEntry.hpp" 56 #include "classfile/systemDictionary.hpp" 57 #include "code/codeCache.hpp" 58 #include "gc/shared/gcLocker.hpp" 59 #include "logging/log.hpp" 60 #include "logging/logStream.hpp" 61 #include "memory/metaspace.hpp" 62 #include "memory/metadataFactory.hpp" 63 #include "memory/oopFactory.hpp" 64 #include "memory/resourceArea.hpp" 65 #include "oops/objArrayOop.inline.hpp" 66 #include "oops/oop.inline.hpp" 67 #include "runtime/atomic.hpp" 68 #include "runtime/javaCalls.hpp" 69 #include "runtime/jniHandles.hpp" 70 #include "runtime/mutex.hpp" 71 #include "runtime/orderAccess.hpp" 72 #include "runtime/safepoint.hpp" 73 #include "runtime/synchronizer.hpp" 74 #include "utilities/ostream.hpp" 75 #if INCLUDE_ALL_GCS 76 #include "gc/g1/g1SATBCardTableModRefBS.hpp" 77 #endif // INCLUDE_ALL_GCS 78 #if INCLUDE_TRACE 79 #include "trace/tracing.hpp" 80 #include "utilities/ticks.hpp" 81 #endif 82 83 void ClassLoaderData::Dependencies::init(TRAPS) { 84 // Create empty dependencies array to add to. CMS requires this to be 85 // an oop so that it can track additions via card marks. We think. 86 _list_head = oopFactory::new_objectArray(2, CHECK); 87 } 88 89 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) { 90 // Check first if this dependency is already in the list. 91 // Save a pointer to the last to add to under the lock. 92 objArrayOop ok = _list_head; 93 objArrayOop last = NULL; 94 while (ok != NULL) { 95 last = ok; 96 if (ok->obj_at(0) == dependency()) { 97 // Don't need to add it 98 return; 99 } 100 ok = (objArrayOop)ok->obj_at(1); 101 } 102 103 // Must handle over GC points 104 assert(last != NULL, "dependencies should be initialized"); 105 objArrayHandle last_handle(THREAD, last); 106 107 // Create a new dependency node with fields for (class_loader or mirror, next) 108 objArrayOop deps = oopFactory::new_objectArray(2, CHECK); 109 deps->obj_at_put(0, dependency()); 110 111 // Must handle over GC points 112 objArrayHandle new_dependency(THREAD, deps); 113 114 // Add the dependency under lock 115 locked_add(last_handle, new_dependency, THREAD); 116 } 117 118 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle, 119 objArrayHandle new_dependency, 120 Thread* THREAD) { 121 122 // Have to lock and put the new dependency on the end of the dependency 123 // array so the card mark for CMS sees that this dependency is new. 124 // Can probably do this lock free with some effort. 125 ObjectLocker ol(Handle(THREAD, _list_head), THREAD); 126 127 oop loader_or_mirror = new_dependency->obj_at(0); 128 129 // Since the dependencies are only added, add to the end. 130 objArrayOop end = last_handle(); 131 objArrayOop last = NULL; 132 while (end != NULL) { 133 last = end; 134 // check again if another thread added it to the end. 135 if (end->obj_at(0) == loader_or_mirror) { 136 // Don't need to add it 137 return; 138 } 139 end = (objArrayOop)end->obj_at(1); 140 } 141 assert(last != NULL, "dependencies should be initialized"); 142 // fill in the first element with the oop in new_dependency. 143 if (last->obj_at(0) == NULL) { 144 last->obj_at_put(0, new_dependency->obj_at(0)); 145 } else { 146 last->obj_at_put(1, new_dependency()); 147 } 148 } 149 150 void ClassLoaderData::Dependencies::oops_do(OopClosure* f) { 151 f->do_oop((oop*)&_list_head); 152 } 153 154 ClassLoaderData::ChunkedHandleList::~ChunkedHandleList() { 155 Chunk* c = _head; 156 while (c != NULL) { 157 Chunk* next = c->_next; 158 delete c; 159 c = next; 160 } 161 } 162 163 oop* ClassLoaderData::ChunkedHandleList::add(oop o) { 164 if (_head == NULL || _head->_size == Chunk::CAPACITY) { 165 Chunk* next = new Chunk(_head); 166 OrderAccess::release_store(&_head, next); 167 } 168 oop* handle = &_head->_data[_head->_size]; 169 *handle = o; 170 OrderAccess::release_store(&_head->_size, _head->_size + 1); 171 return handle; 172 } 173 174 void ClassLoaderData::ChunkedHandleList::oops_do(OopClosure* f) { 175 Chunk* head = OrderAccess::load_acquire(&_head); 176 if (head != NULL) { 177 // Must be careful when reading size of head 178 oops_do_chunk(f, head, OrderAccess::load_acquire(&head->_size)); 179 for (Chunk* c = head->_next; c != NULL; c = c->_next) { 180 oops_do_chunk(f, c, c->_size); 181 } 182 } 183 } 184 185 inline void ClassLoaderData::ChunkedHandleList::oops_do_chunk(OopClosure* f, Chunk* c, const juint size) { 186 for (juint i = 0; i < size; i++) { 187 if (c->_data[i] != NULL) { 188 f->do_oop(&c->_data[i]); 189 } 190 } 191 } 192 193 #ifdef ASSERT 194 class VerifyContainsOopClosure : public OopClosure { 195 oop* _target; 196 bool _found; 197 198 public: 199 VerifyContainsOopClosure(oop* target) : _target(target), _found(false) {} 200 201 void do_oop(oop* p) { 202 if (p == _target) { 203 _found = true; 204 } 205 } 206 207 void do_oop(narrowOop* p) { 208 // The ChunkedHandleList should not contain any narrowOop 209 ShouldNotReachHere(); 210 } 211 212 bool found() const { 213 return _found; 214 } 215 }; 216 217 bool ClassLoaderData::ChunkedHandleList::contains(oop* p) { 218 VerifyContainsOopClosure cl(p); 219 oops_do(&cl); 220 return cl.found(); 221 } 222 #endif // ASSERT 223 224 static const int _boot_loader_dictionary_size = 1009; 225 static const int _default_loader_dictionary_size = 107; 226 227 static Dictionary* create_dictionary(ClassLoaderData* cld) { 228 assert(cld != NULL, "invariant"); 229 assert(!cld->is_anonymous(), "anonymous class loader data do not have a dictionary"); 230 231 int size; 232 bool resizable = false; 233 if (ClassLoaderData::the_null_class_loader_data() == NULL) { 234 size = _boot_loader_dictionary_size; 235 resizable = true; 236 } else if (cld->class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) { 237 size = 1; // there's only one class in relection class loader and no initiated classes 238 } else if (cld->is_system_class_loader_data()) { 239 size = _boot_loader_dictionary_size; 240 resizable = true; 241 } else { 242 size = _default_loader_dictionary_size; 243 resizable = true; 244 } 245 if (!DynamicallyResizeSystemDictionaries || DumpSharedSpaces || UseSharedSpaces) { 246 resizable = false; 247 } 248 return new Dictionary(cld, size, resizable); 249 } 250 251 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL; 252 253 void ClassLoaderData::init_null_class_loader_data() { 254 assert(_the_null_class_loader_data == NULL, "cannot initialize twice"); 255 assert(ClassLoaderDataGraph::_head == NULL, "cannot initialize twice"); 256 257 // We explicitly initialize the Dependencies object at a later phase in the initialization 258 _the_null_class_loader_data = new ClassLoaderData(Handle(), false, Dependencies()); 259 ClassLoaderDataGraph::_head = _the_null_class_loader_data; 260 assert(_the_null_class_loader_data->is_the_null_class_loader_data(), "Must be"); 261 } 262 263 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous, Dependencies dependencies) : 264 _class_loader(h_class_loader()), 265 _is_anonymous(is_anonymous), 266 // An anonymous class loader data doesn't have anything to keep 267 // it from being unloaded during parsing of the anonymous class. 268 // The null-class-loader should always be kept alive. 269 _keep_alive((is_anonymous || h_class_loader.is_null()) ? 1 : 0), 270 _metaspace(NULL), _unloading(false), _klasses(NULL), 271 _modules(NULL), _packages(NULL), 272 _claimed(0), _modified_oops(true), _accumulated_modified_oops(false), 273 _jmethod_ids(NULL), _handles(), _deallocate_list(NULL), 274 _next(NULL), _dependencies(dependencies), 275 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true, 276 Monitor::_safepoint_check_never)) { 277 278 // A ClassLoaderData created solely for an anonymous class should never have a 279 // ModuleEntryTable or PackageEntryTable created for it. The defining package 280 // and module for an anonymous class will be found in its host class. 281 if (!is_anonymous) { 282 _packages = new PackageEntryTable(PackageEntryTable::_packagetable_entry_size); 283 if (h_class_loader.is_null()) { 284 // Create unnamed module for boot loader 285 _unnamed_module = ModuleEntry::create_boot_unnamed_module(this); 286 } else { 287 // Create unnamed module for all other loaders 288 _unnamed_module = ModuleEntry::create_unnamed_module(this); 289 } 290 } else { 291 _unnamed_module = NULL; 292 } 293 294 if (!is_anonymous) { 295 _dictionary = create_dictionary(this); 296 } else { 297 _dictionary = NULL; 298 } 299 TRACE_INIT_ID(this); 300 } 301 302 ClassLoaderData::~ClassLoaderData() { 303 // Release C heap structures for all the classes. 304 classes_do(InstanceKlass::release_C_heap_structures); 305 306 // Release C heap allocated hashtable for all the packages. 307 if (_packages != NULL) { 308 // Destroy the table itself 309 delete _packages; 310 _packages = NULL; 311 } 312 313 // Release C heap allocated hashtable for all the modules. 314 if (_modules != NULL) { 315 // Destroy the table itself 316 delete _modules; 317 _modules = NULL; 318 } 319 320 // Release C heap allocated hashtable for the dictionary 321 if (_dictionary != NULL) { 322 // Destroy the table itself 323 delete _dictionary; 324 _dictionary = NULL; 325 } 326 327 if (_unnamed_module != NULL) { 328 _unnamed_module->delete_unnamed_module(); 329 _unnamed_module = NULL; 330 } 331 332 // release the metaspace 333 Metaspace *m = _metaspace; 334 if (m != NULL) { 335 _metaspace = NULL; 336 delete m; 337 } 338 // Clear all the JNI handles for methods 339 // These aren't deallocated and are going to look like a leak, but that's 340 // needed because we can't really get rid of jmethodIDs because we don't 341 // know when native code is going to stop using them. The spec says that 342 // they're "invalid" but existing programs likely rely on their being 343 // NULL after class unloading. 344 if (_jmethod_ids != NULL) { 345 Method::clear_jmethod_ids(this); 346 } 347 // Delete lock 348 delete _metaspace_lock; 349 350 // Delete free list 351 if (_deallocate_list != NULL) { 352 delete _deallocate_list; 353 } 354 } 355 356 void ClassLoaderData::init_dependencies(TRAPS) { 357 assert(!Universe::is_fully_initialized(), "should only be called when initializing"); 358 assert(is_the_null_class_loader_data(), "should only call this for the null class loader"); 359 _dependencies.init(CHECK); 360 } 361 362 // Deallocate free metadata on the free list. How useful the PermGen was! 363 void ClassLoaderData::free_deallocate_list() { 364 // Don't need lock, at safepoint 365 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 366 assert(!is_unloading(), "only called for ClassLoaderData that are not unloading"); 367 if (_deallocate_list == NULL) { 368 return; 369 } 370 // Go backwards because this removes entries that are freed. 371 for (int i = _deallocate_list->length() - 1; i >= 0; i--) { 372 Metadata* m = _deallocate_list->at(i); 373 if (!m->on_stack()) { 374 _deallocate_list->remove_at(i); 375 // There are only three types of metadata that we deallocate directly. 376 // Cast them so they can be used by the template function. 377 if (m->is_method()) { 378 MetadataFactory::free_metadata(this, (Method*)m); 379 } else if (m->is_constantPool()) { 380 MetadataFactory::free_metadata(this, (ConstantPool*)m); 381 } else if (m->is_klass()) { 382 MetadataFactory::free_metadata(this, (InstanceKlass*)m); 383 } else { 384 ShouldNotReachHere(); 385 } 386 } else { 387 // Metadata is alive. 388 // If scratch_class is on stack then it shouldn't be on this list! 389 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(), 390 "scratch classes on this list should be dead"); 391 // Also should assert that other metadata on the list was found in handles. 392 } 393 } 394 } 395 396 // This is distinct from free_deallocate_list. For class loader data that are 397 // unloading, this frees the C heap memory for constant pools on the list. If there 398 // were C heap memory allocated for methods, it would free that too. The C heap memory 399 // for InstanceKlasses on this list is freed in the ClassLoaderData destructor. 400 void ClassLoaderData::unload_deallocate_list() { 401 // Don't need lock, at safepoint 402 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 403 assert(is_unloading(), "only called for ClassLoaderData that are unloading"); 404 if (_deallocate_list == NULL) { 405 return; 406 } 407 // Go backwards because this removes entries that are freed. 408 for (int i = _deallocate_list->length() - 1; i >= 0; i--) { 409 Metadata* m = _deallocate_list->at(i); 410 assert(!m->on_stack(), "wouldn't be unloading if this were so"); 411 _deallocate_list->remove_at(i); 412 // Only constant pool entries have C heap memory to free. 413 if (m->is_constantPool()) { 414 ((ConstantPool*)m)->release_C_heap_structures(); 415 } 416 } 417 } 418 419 // Class iterator used by the compiler. It gets some number of classes at 420 // a safepoint to decay invocation counters on the methods. 421 class ClassLoaderDataGraphKlassIteratorStatic { 422 friend class ClassLoaderData; 423 friend class ClassLoaderDataGraph; 424 private: 425 ClassLoaderData* _current_loader_data; 426 Klass* _current_class_entry; 427 428 InstanceKlass* try_get_next_class() { 429 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 430 int max_classes = InstanceKlass::number_of_instance_classes(); 431 assert(max_classes > 0, "should not be called with no instance classes"); 432 for (int i = 0; i < max_classes; ) { 433 434 if (_current_class_entry != NULL) { 435 Klass* k = _current_class_entry; 436 _current_class_entry = _current_class_entry->next_link(); 437 438 if (k->is_instance_klass()) { 439 InstanceKlass* ik = InstanceKlass::cast(k); 440 i++; // count all instance classes found 441 // Not yet loaded classes are counted in max_classes 442 // but only return loaded classes. 443 if (ik->is_loaded()) { 444 return ik; 445 } 446 } 461 // Caller handles NULL. 462 return NULL; 463 } 464 465 // If the current class for the static iterator is a class being unloaded or 466 // deallocated, adjust the current class. 467 void adjust_saved_class(ClassLoaderData* cld) { 468 if (_current_loader_data == cld) { 469 _current_loader_data = cld->next(); 470 if (_current_loader_data != NULL) { 471 _current_class_entry = _current_loader_data->klasses(); 472 } // else try_get_next_class will start at the head 473 } 474 } 475 476 void adjust_saved_class(Klass* klass) { 477 if (_current_class_entry == klass) { 478 _current_class_entry = klass->next_link(); 479 } 480 } 481 482 public: 483 ClassLoaderDataGraphKlassIteratorStatic() : _current_loader_data(NULL), _current_class_entry(NULL) {} 484 }; 485 486 static ClassLoaderDataGraphKlassIteratorStatic static_klass_iterator; 487 488 void ClassLoaderData::unload() { 489 _unloading = true; 490 491 // Tell serviceability tools these classes are unloading 492 classes_do(InstanceKlass::notify_unload_class); 493 494 LogTarget(Debug, class, loader, data) lt; 495 if (lt.is_enabled()) { 496 ResourceMark rm; 497 LogStream ls(lt); 498 ls.print(": unload loader data " INTPTR_FORMAT, p2i(this)); 499 ls.print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()), 500 loader_name()); 501 if (is_anonymous()) { 502 ls.print(" for anonymous class " INTPTR_FORMAT " ", p2i(_klasses)); 503 } 504 ls.cr(); 505 } 506 507 // Some items on the _deallocate_list need to free their C heap structures 508 // if they are not already on the _klasses list. 509 unload_deallocate_list(); 510 511 // Clean up global class iterator for compiler 512 static_klass_iterator.adjust_saved_class(this); 513 } 514 515 void ClassLoaderData::classes_do(KlassClosure* klass_closure) { 516 // Lock-free access requires load_acquire 517 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 518 klass_closure->do_klass(k); 519 assert(k != k->next_link(), "no loops!"); 520 } 521 } 522 523 void ClassLoaderData::classes_do(void f(Klass * const)) { 524 // Lock-free access requires load_acquire 525 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 526 f(k); 527 assert(k != k->next_link(), "no loops!"); 528 } 529 } 530 531 void ClassLoaderData::classes_do(void f(InstanceKlass*)) { 532 // Lock-free access requires load_acquire 533 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 534 if (k->is_instance_klass()) { 535 f(InstanceKlass::cast(k)); 536 } 537 assert(k != k->next_link(), "no loops!"); 538 } 539 } 540 541 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) { 542 // Lock-free access requires load_acquire 543 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 544 // Do not filter ArrayKlass oops here... 545 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) { 546 klass_closure->do_klass(k); 547 } 548 } 549 } 550 551 void ClassLoaderData::methods_do(void f(Method*)) { 552 // Lock-free access requires load_acquire 553 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 554 if (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded()) { 555 InstanceKlass::cast(k)->methods_do(f); 556 } 557 } 558 } 559 560 void ClassLoaderData::modules_do(void f(ModuleEntry*)) { 561 assert_locked_or_safepoint(Module_lock); 562 if (_unnamed_module != NULL) { 563 f(_unnamed_module); 564 } 565 if (_modules != NULL) { 566 for (int i = 0; i < _modules->table_size(); i++) { 567 for (ModuleEntry* entry = _modules->bucket(i); 568 entry != NULL; 569 entry = entry->next()) { 570 f(entry); 571 } 572 } 573 } 574 } 575 576 void ClassLoaderData::packages_do(void f(PackageEntry*)) { 577 assert_locked_or_safepoint(Module_lock); 578 if (_packages != NULL) { 579 for (int i = 0; i < _packages->table_size(); i++) { 580 for (PackageEntry* entry = _packages->bucket(i); 581 entry != NULL; 582 entry = entry->next()) { 583 f(entry); 584 } 585 } 586 } 587 } 588 589 void ClassLoaderData::oops_do(OopClosure* f, bool must_claim, bool clear_mod_oops) { 590 if (must_claim && !claim()) { 591 return; 592 } 593 594 // Only clear modified_oops after the ClassLoaderData is claimed. 595 if (clear_mod_oops) { 596 clear_modified_oops(); 597 } 598 599 f->do_oop(&_class_loader); 600 _dependencies.oops_do(f); 601 _handles.oops_do(f); 602 } 603 604 // Unloading support 605 oop ClassLoaderData::keep_alive_object() const { 606 assert_locked_or_safepoint(_metaspace_lock); 607 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive"); 608 return is_anonymous() ? _klasses->java_mirror() : class_loader(); 609 } 610 611 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const { 612 return keep_alive() // null class loader and incomplete anonymous klasses. 613 || is_alive_closure->do_object_b(keep_alive_object()); 614 } 615 616 // Anonymous classes have their own ClassLoaderData that is marked to keep alive 617 // while the class is being parsed, and if the class appears on the module fixup list. 618 // Due to the uniqueness that no other class shares the anonymous class' name or 619 // ClassLoaderData, no other non-GC thread has knowledge of the anonymous class while 620 // it is being defined, therefore _keep_alive is not volatile or atomic. 621 void ClassLoaderData::inc_keep_alive() { 622 if (is_anonymous()) { 623 assert(_keep_alive >= 0, "Invalid keep alive increment count"); 624 _keep_alive++; 625 } 626 } 627 628 void ClassLoaderData::dec_keep_alive() { 629 if (is_anonymous()) { 630 assert(_keep_alive > 0, "Invalid keep alive decrement count"); 631 _keep_alive--; 632 } 633 } 634 635 bool ClassLoaderData::claim() { 636 if (_claimed == 1) { 637 return false; 638 } 639 640 return (int)Atomic::cmpxchg(1, &_claimed, 0) == 0; 641 } 642 643 Metaspace* ClassLoaderData::metaspace_non_null() { 644 // If the metaspace has not been allocated, create a new one. Might want 645 // to create smaller arena for Reflection class loaders also. 646 // The reason for the delayed allocation is because some class loaders are 647 // simply for delegating with no metadata of their own. 648 // Lock-free access requires load_acquire. 649 Metaspace* metaspace = OrderAccess::load_acquire(&_metaspace); 650 if (metaspace == NULL) { 651 MutexLockerEx ml(_metaspace_lock, Mutex::_no_safepoint_check_flag); 652 // Check if _metaspace got allocated while we were waiting for this lock. 653 if ((metaspace = _metaspace) == NULL) { 654 if (this == the_null_class_loader_data()) { 655 assert(class_loader() == NULL, "Must be"); 656 metaspace = new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType); 657 } else if (is_anonymous()) { 658 if (class_loader() != NULL) { 659 log_trace(class, loader, data)("is_anonymous: %s", class_loader()->klass()->internal_name()); 660 } 661 metaspace = new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType); 662 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) { 663 if (class_loader() != NULL) { 664 log_trace(class, loader, data)("is_reflection: %s", class_loader()->klass()->internal_name()); 665 } 666 metaspace = new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType); 667 } else { 668 metaspace = new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType); 669 } 670 // Ensure _metaspace is stable, since it is examined without a lock 671 OrderAccess::release_store(&_metaspace, metaspace); 672 } 673 } 674 return metaspace; 675 } 676 677 // Returns true if this class loader data is for the system class loader. 678 bool ClassLoaderData::is_system_class_loader_data() const { 679 return SystemDictionary::is_system_class_loader(class_loader()); 680 } 681 682 // Returns true if this class loader data is for the platform class loader. 683 bool ClassLoaderData::is_platform_class_loader_data() const { 684 return SystemDictionary::is_platform_class_loader(class_loader()); 685 } 686 687 // Returns true if this class loader data is one of the 3 builtin 688 // (boot, application/system or platform) class loaders. Note, the 689 // builtin loaders are not freed by a GC. 690 bool ClassLoaderData::is_builtin_class_loader_data() const { 691 return (is_the_null_class_loader_data() || 692 SystemDictionary::is_system_class_loader(class_loader()) || 693 SystemDictionary::is_platform_class_loader(class_loader())); 694 } 695 696 const char* ClassLoaderData::loader_name() { 697 // Handles null class loader 698 return SystemDictionary::loader_name(class_loader()); 699 } 700 701 ModuleEntryTable* ClassLoaderData::modules() { 702 // Lazily create the module entry table at first request. 703 // Lock-free access requires load_acquire. 704 ModuleEntryTable* modules = OrderAccess::load_acquire(&_modules); 705 if (modules == NULL) { 706 MutexLocker m1(Module_lock); 707 // Check if _modules got allocated while we were waiting for this lock. 708 if ((modules = _modules) == NULL) { 709 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size); 710 711 { 712 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag); 713 // Ensure _modules is stable, since it is examined without a lock 714 OrderAccess::release_store(&_modules, modules); 715 } 716 } 717 } 718 return modules; 719 } 720 721 OopHandle ClassLoaderData::add_handle(Handle h) { 722 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 723 record_modified_oops(); 724 return OopHandle(_handles.add(h())); 725 } 726 727 void ClassLoaderData::remove_handle(OopHandle h) { 728 assert(!is_unloading(), "Do not remove a handle for a CLD that is unloading"); 729 oop* ptr = h.ptr_raw(); 730 if (ptr != NULL) { 731 assert(_handles.contains(ptr), "Got unexpected handle " PTR_FORMAT, p2i(ptr)); 732 #if INCLUDE_ALL_GCS 733 // This barrier is used by G1 to remember the old oop values, so 734 // that we don't forget any objects that were live at the snapshot at 735 // the beginning. 736 if (UseG1GC) { 737 oop obj = *ptr; 738 if (obj != NULL) { 739 G1SATBCardTableModRefBS::enqueue(obj); 740 } 741 } 742 #endif 743 *ptr = NULL; 744 } 745 } 746 747 void ClassLoaderData::init_handle_locked(OopHandle& dest, Handle h) { 748 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 749 if (dest.resolve() != NULL) { 750 return; 751 } else { 752 dest = _handles.add(h()); 753 } 754 } 755 756 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) { 757 { 758 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 759 Klass* old_value = _klasses; 760 k->set_next_link(old_value); 761 // Link the new item into the list, making sure the linked class is stable 762 // since the list can be walked without a lock 763 OrderAccess::release_store(&_klasses, k); 764 } 765 766 if (publicize && k->class_loader_data() != NULL) { 767 ResourceMark rm; 768 log_trace(class, loader, data)("Adding k: " PTR_FORMAT " %s to CLD: " 769 PTR_FORMAT " loader: " PTR_FORMAT " %s", 770 p2i(k), 771 k->external_name(), 772 p2i(k->class_loader_data()), 773 p2i((void *)k->class_loader()), 774 loader_name()); 775 } 776 } 777 778 // Remove a klass from the _klasses list for scratch_class during redefinition 779 // or parsed class in the case of an error. 780 void ClassLoaderData::remove_class(Klass* scratch_class) { 781 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 782 783 // Adjust global class iterator. 784 static_klass_iterator.adjust_saved_class(scratch_class); 785 786 Klass* prev = NULL; 787 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 788 if (k == scratch_class) { 789 if (prev == NULL) { 790 _klasses = k->next_link(); 791 } else { 792 Klass* next = k->next_link(); 793 prev->set_next_link(next); 794 } 795 return; 796 } 797 prev = k; 798 assert(k != k->next_link(), "no loops!"); 799 } 800 ShouldNotReachHere(); // should have found this class!! 801 } 802 803 bool ClassLoaderData::contains_klass(Klass* klass) { 804 // Lock-free access requires load_acquire 805 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 806 if (k == klass) return true; 807 } 808 return false; 809 } 810 811 void ClassLoaderData::record_dependency(const Klass* k, TRAPS) { 812 assert(k != NULL, "invariant"); 813 814 ClassLoaderData * const from_cld = this; 815 ClassLoaderData * const to_cld = k->class_loader_data(); 816 817 // Dependency to the null class loader data doesn't need to be recorded 818 // because the null class loader data never goes away. 819 if (to_cld->is_the_null_class_loader_data()) { 820 return; 821 } 822 823 oop to; 824 if (to_cld->is_anonymous()) { 825 // Anonymous class dependencies are through the mirror. 826 to = k->java_mirror(); 827 } else { 828 to = to_cld->class_loader(); 829 830 // If from_cld is anonymous, even if it's class_loader is a parent of 'to' 831 // we still have to add it. The class_loader won't keep from_cld alive. 832 if (!from_cld->is_anonymous()) { 833 // Check that this dependency isn't from the same or parent class_loader 834 oop from = from_cld->class_loader(); 835 836 oop curr = from; 837 while (curr != NULL) { 838 if (curr == to) { 839 return; // this class loader is in the parent list, no need to add it. 840 } 841 curr = java_lang_ClassLoader::parent(curr); 842 } 843 } 844 } 845 846 // It's a dependency we won't find through GC, add it. This is relatively rare 847 // Must handle over GC point. 848 Handle dependency(THREAD, to); 849 from_cld->_dependencies.add(dependency, CHECK); 850 851 // Added a potentially young gen oop to the ClassLoaderData 852 record_modified_oops(); 853 } 854 855 // Add this metadata pointer to be freed when it's safe. This is only during 856 // class unloading because Handles might point to this metadata field. 857 void ClassLoaderData::add_to_deallocate_list(Metadata* m) { 858 // Metadata in shared region isn't deleted. 859 if (!m->is_shared()) { 860 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 861 if (_deallocate_list == NULL) { 862 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true); 863 } 864 _deallocate_list->append_if_missing(m); 865 } 866 } 867 868 #ifndef PRODUCT 869 // Define to dump klasses 870 #undef CLD_DUMP_KLASSES 871 872 void ClassLoaderData::dump(outputStream * const out) { 873 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: " PTR_FORMAT " %s {", 874 p2i(this), p2i((void *)class_loader()), 875 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name()); 876 if (claimed()) out->print(" claimed "); 877 if (is_unloading()) out->print(" unloading "); 878 out->cr(); 879 if (metaspace_or_null() != NULL) { 880 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null())); 881 metaspace_or_null()->dump(out); 882 } else { 883 out->print_cr("metaspace: NULL"); 884 } 885 886 #ifdef CLD_DUMP_KLASSES 887 if (Verbose) { 888 Klass* k = _klasses; 889 while (k != NULL) { 890 out->print_cr("klass " PTR_FORMAT ", %s", p2i(k), k->name()->as_C_string()); 891 assert(k != k->next_link(), "no loops!"); 892 k = k->next_link(); 893 } 894 } 895 #endif // CLD_DUMP_KLASSES 896 #undef CLD_DUMP_KLASSES 897 if (_jmethod_ids != NULL) { 898 Method::print_jmethod_ids(this, out); 899 } 900 out->print_cr("}"); 901 } 902 903 void ClassLoaderData::verify() { 904 assert_locked_or_safepoint(_metaspace_lock); 905 oop cl = class_loader(); 906 907 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same"); 908 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be"); 909 910 // Verify the integrity of the allocated space. 911 if (metaspace_or_null() != NULL) { 912 metaspace_or_null()->verify(); 913 } 914 915 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 916 guarantee(k->class_loader_data() == this, "Must be the same"); 917 k->verify(); 918 assert(k != k->next_link(), "no loops!"); 919 } 920 } 921 922 #endif // !PRODUCT 923 924 void ClassLoaderData::print_value_on(outputStream* out) const { 925 if (class_loader() == NULL) { 926 out->print("NULL class loader"); 927 } else { 928 out->print("class loader " INTPTR_FORMAT " ", p2i(this)); 929 class_loader()->print_value_on(out); 930 } 931 } 932 933 void ClassLoaderData::print_on(outputStream* out) const { 934 if (class_loader() == NULL) { 935 out->print("NULL class loader"); 936 } else { 937 out->print("class loader " INTPTR_FORMAT " ", p2i(this)); 938 class_loader()->print_on(out); 939 } 940 } 941 942 943 // GC root of class loader data created. 944 ClassLoaderData* ClassLoaderDataGraph::_head = NULL; 945 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL; 946 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL; 947 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL; 948 949 bool ClassLoaderDataGraph::_should_purge = false; 950 bool ClassLoaderDataGraph::_metaspace_oom = false; 951 952 static void print_creation(outputStream* out, Handle loader, ClassLoaderData* cld, TRAPS) { 953 Handle string; 954 if (loader.not_null()) { 955 // Include the result of loader.toString() in the output. This allows 956 // the user of the log to identify the class loader instance. 957 JavaValue result(T_OBJECT); 958 Klass* spec_klass = SystemDictionary::ClassLoader_klass(); 959 JavaCalls::call_virtual(&result, 960 loader, 961 spec_klass, 962 vmSymbols::toString_name(), 963 vmSymbols::void_string_signature(), 964 CHECK); 965 assert(result.get_type() == T_OBJECT, "just checking"); 966 string = Handle(THREAD, (oop)result.get_jobject()); 967 } 968 969 ResourceMark rm; 970 out->print("create class loader data " INTPTR_FORMAT, p2i(cld)); 971 out->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()), 972 cld->loader_name()); 973 974 if (string.not_null()) { 975 out->print(": "); 976 java_lang_String::print(string(), out); 977 } 978 out->cr(); 979 } 980 981 // Add a new class loader data node to the list. Assign the newly created 982 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field 983 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) { 984 // We need to allocate all the oops for the ClassLoaderData before allocating the 985 // actual ClassLoaderData object. 986 ClassLoaderData::Dependencies dependencies(CHECK_NULL); 987 988 NoSafepointVerifier no_safepoints; // we mustn't GC until we've installed the 989 // ClassLoaderData in the graph since the CLD 990 // contains unhandled oops 991 992 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies); 993 994 995 if (!is_anonymous) { 996 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader()); 997 // First, Atomically set it 998 ClassLoaderData* old = Atomic::cmpxchg(cld, cld_addr, (ClassLoaderData*)NULL); 999 if (old != NULL) { 1000 delete cld; 1007 // class loader data 1008 ClassLoaderData** list_head = &_head; 1009 ClassLoaderData* next = _head; 1010 1011 do { 1012 cld->set_next(next); 1013 ClassLoaderData* exchanged = Atomic::cmpxchg(cld, list_head, next); 1014 if (exchanged == next) { 1015 LogTarget(Debug, class, loader, data) lt; 1016 if (lt.is_enabled()) { 1017 PauseNoSafepointVerifier pnsv(&no_safepoints); // Need safe points for JavaCalls::call_virtual 1018 LogStream ls(lt); 1019 print_creation(&ls, loader, cld, CHECK_NULL); 1020 } 1021 return cld; 1022 } 1023 next = exchanged; 1024 } while (true); 1025 } 1026 1027 void ClassLoaderDataGraph::oops_do(OopClosure* f, bool must_claim) { 1028 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 1029 cld->oops_do(f, must_claim); 1030 } 1031 } 1032 1033 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, bool must_claim) { 1034 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 1035 if (cld->keep_alive()) { 1036 cld->oops_do(f, must_claim); 1037 } 1038 } 1039 } 1040 1041 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, bool must_claim) { 1042 if (ClassUnloading) { 1043 keep_alive_oops_do(f, must_claim); 1044 } else { 1045 oops_do(f, must_claim); 1046 } 1219 ls.cr(); 1220 } 1221 } 1222 1223 curr = curr->_next; 1224 } 1225 1226 return array; 1227 } 1228 1229 bool ClassLoaderDataGraph::unload_list_contains(const void* x) { 1230 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint"); 1231 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) { 1232 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) { 1233 return true; 1234 } 1235 } 1236 return false; 1237 } 1238 1239 #if INCLUDE_TRACE 1240 static Ticks class_unload_time; 1241 static void post_class_unload_event(Klass* const k) { 1242 assert(k != NULL, "invariant"); 1243 EventClassUnload event(UNTIMED); 1244 event.set_endtime(class_unload_time); 1245 event.set_unloadedClass(k); 1246 event.set_definingClassLoader(k->class_loader_data()); 1247 event.commit(); 1248 } 1249 #endif // INCLUDE_TRACE 1250 1251 static void post_class_unload_events() { 1252 #if INCLUDE_TRACE 1253 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 1254 if (Tracing::enabled()) { 1255 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) { 1256 class_unload_time = Ticks::now(); 1257 ClassLoaderDataGraph::classes_unloading_do(&post_class_unload_event); 1258 } 1259 Tracing::on_unloading_classes(); 1260 } 1261 #endif // INCLUDE_TRACE 1262 } 1263 1264 // Move class loader data from main list to the unloaded list for unloading 1265 // and deallocation later. 1266 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure, 1267 bool clean_previous_versions) { 1268 1269 ClassLoaderData* data = _head; 1270 ClassLoaderData* prev = NULL; 1271 bool seen_dead_loader = false; 1272 1273 // Mark metadata seen on the stack only so we can delete unneeded entries. 1274 // Only walk all metadata, including the expensive code cache walk, for Full GC 1275 // and only if class redefinition and if there's previous versions of 1276 // Klasses to delete. 1277 bool walk_all_metadata = clean_previous_versions && 1278 JvmtiExport::has_redefined_a_class() && 1279 InstanceKlass::has_previous_versions_and_reset(); 1280 MetadataOnStackMark md_on_stack(walk_all_metadata); 1281 1282 // Save previous _unloading pointer for CMS which may add to unloading list before 1342 } 1343 1344 void ClassLoaderDataGraph::purge() { 1345 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 1346 ClassLoaderData* list = _unloading; 1347 _unloading = NULL; 1348 ClassLoaderData* next = list; 1349 bool classes_unloaded = false; 1350 while (next != NULL) { 1351 ClassLoaderData* purge_me = next; 1352 next = purge_me->next(); 1353 delete purge_me; 1354 classes_unloaded = true; 1355 } 1356 if (classes_unloaded) { 1357 Metaspace::purge(); 1358 set_metaspace_oom(false); 1359 } 1360 } 1361 1362 void ClassLoaderDataGraph::clear_claimed_marks() { 1363 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 1364 cld->clear_claimed(); 1365 } 1366 } 1367 1368 int ClassLoaderDataGraph::resize_if_needed() { 1369 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 1370 int resized = 0; 1371 if (Dictionary::does_any_dictionary_needs_resizing()) { 1372 FOR_ALL_DICTIONARY(cld) { 1373 if (cld->dictionary()->resize_if_needed()) { 1374 resized++; 1375 } 1376 } 1377 } 1378 return resized; 1379 } 1380 1381 InstanceKlass* ClassLoaderDataGraph::try_get_next_class() { 1382 return static_klass_iterator.try_get_next_class(); 1383 } 1384 1385 #ifndef PRODUCT 1386 void ClassLoaderDataGraph::verify() { 1387 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 1388 data->verify(); 1389 } 1390 } 1391 1392 void ClassLoaderDataGraph::dump_on(outputStream * const out) { 1393 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 1394 data->dump(out); 1395 } 1396 MetaspaceAux::dump(out); 1397 } 1398 1399 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) { 1400 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 1401 if (loader_data == data) { 1402 return true; 1403 } 1404 } 1405 return false; 1406 } 1407 1408 // callable from debugger 1409 extern "C" int print_loader_data_graph() { 1410 ClassLoaderDataGraph::dump_on(tty); 1411 return 0; 1412 } 1413 1414 #endif // !PRODUCT 1415 1416 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic() 1417 : _next_klass(NULL) { 1418 ClassLoaderData* cld = ClassLoaderDataGraph::_head; 1419 Klass* klass = NULL; 1420 1421 // Find the first klass in the CLDG. 1422 while (cld != NULL) { 1423 assert_locked_or_safepoint(cld->metaspace_lock()); 1424 klass = cld->_klasses; 1425 if (klass != NULL) { 1426 _next_klass = klass; 1427 return; 1428 } 1429 cld = cld->next(); 1430 } 1431 } 1432 1433 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) { 1434 Klass* next = klass->next_link(); 1435 if (next != NULL) { 1453 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() { 1454 Klass* head = _next_klass; 1455 1456 while (head != NULL) { 1457 Klass* next = next_klass_in_cldg(head); 1458 1459 Klass* old_head = Atomic::cmpxchg(next, &_next_klass, head); 1460 1461 if (old_head == head) { 1462 return head; // Won the CAS. 1463 } 1464 1465 head = old_head; 1466 } 1467 1468 // Nothing more for the iterator to hand out. 1469 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head)); 1470 return NULL; 1471 } 1472 1473 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() : 1474 _data(ClassLoaderDataGraph::_head) { 1475 } |