1 /* 2 * Copyright (c) 2012, 2018, 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 // A ClassLoaderData identifies the full set of class types that a class 26 // loader's name resolution strategy produces for a given configuration of the 27 // class loader. 28 // Class types in the ClassLoaderData may be defined by from class file binaries 29 // provided by the class loader, or from other class loader it interacts with 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 "logging/log.hpp" 60 #include "logging/logStream.hpp" 61 #include "memory/allocation.inline.hpp" 62 #include "memory/metadataFactory.hpp" 63 #include "memory/metaspaceShared.hpp" 64 #include "memory/oopFactory.hpp" 65 #include "memory/resourceArea.hpp" 66 #include "oops/access.inline.hpp" 67 #include "oops/objArrayOop.inline.hpp" 68 #include "oops/oop.inline.hpp" 69 #include "runtime/atomic.hpp" 70 #include "runtime/handles.inline.hpp" 71 #include "runtime/javaCalls.hpp" 72 #include "runtime/jniHandles.hpp" 73 #include "runtime/mutex.hpp" 74 #include "runtime/orderAccess.hpp" 75 #include "runtime/safepoint.hpp" 76 #include "runtime/safepointVerifiers.hpp" 77 #include "runtime/synchronizer.hpp" 78 #include "utilities/growableArray.hpp" 79 #include "utilities/macros.hpp" 80 #include "utilities/ostream.hpp" 81 #if INCLUDE_TRACE 82 #include "trace/tracing.hpp" 83 #endif 84 85 volatile size_t ClassLoaderDataGraph::_num_array_classes = 0; 86 volatile size_t ClassLoaderDataGraph::_num_instance_classes = 0; 87 88 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL; 89 90 void ClassLoaderData::init_null_class_loader_data() { 91 assert(_the_null_class_loader_data == NULL, "cannot initialize twice"); 92 assert(ClassLoaderDataGraph::_head == NULL, "cannot initialize twice"); 93 94 _the_null_class_loader_data = new ClassLoaderData(Handle(), false); 95 ClassLoaderDataGraph::_head = _the_null_class_loader_data; 96 assert(_the_null_class_loader_data->is_the_null_class_loader_data(), "Must be"); 97 98 LogTarget(Debug, class, loader, data) lt; 99 if (lt.is_enabled()) { 100 ResourceMark rm; 101 LogStream ls(lt); 102 ls.print("create "); 103 _the_null_class_loader_data->print_value_on(&ls); 104 ls.cr(); 105 } 106 } 107 108 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous) : 109 _class_loader(h_class_loader()), 110 _is_anonymous(is_anonymous), 111 // An anonymous class loader data doesn't have anything to keep 112 // it from being unloaded during parsing of the anonymous class. 113 // The null-class-loader should always be kept alive. 114 _keep_alive((is_anonymous || h_class_loader.is_null()) ? 1 : 0), 115 _metaspace(NULL), _unloading(false), _klasses(NULL), 116 _modules(NULL), _packages(NULL), 117 _claimed(0), _modified_oops(true), _accumulated_modified_oops(false), 118 _jmethod_ids(NULL), _handles(), _deallocate_list(NULL), 119 _next(NULL), 120 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true, 121 Monitor::_safepoint_check_never)) { 122 123 // A ClassLoaderData created solely for an anonymous class should never have a 124 // ModuleEntryTable or PackageEntryTable created for it. The defining package 125 // and module for an anonymous class will be found in its host class. 126 if (!is_anonymous) { 127 _packages = new PackageEntryTable(PackageEntryTable::_packagetable_entry_size); 128 if (h_class_loader.is_null()) { 129 // Create unnamed module for boot loader 130 _unnamed_module = ModuleEntry::create_boot_unnamed_module(this); 131 } else { 132 // Create unnamed module for all other loaders 133 _unnamed_module = ModuleEntry::create_unnamed_module(this); 134 } 135 _dictionary = create_dictionary(); 136 } else { 137 _packages = NULL; 138 _unnamed_module = NULL; 139 _dictionary = NULL; 140 } 141 142 NOT_PRODUCT(_dependency_count = 0); // number of class loader dependencies 143 144 TRACE_INIT_ID(this); 145 } 146 147 ClassLoaderData::ChunkedHandleList::~ChunkedHandleList() { 148 Chunk* c = _head; 149 while (c != NULL) { 150 Chunk* next = c->_next; 151 delete c; 152 c = next; 153 } 154 } 155 156 oop* ClassLoaderData::ChunkedHandleList::add(oop o) { 157 if (_head == NULL || _head->_size == Chunk::CAPACITY) { 158 Chunk* next = new Chunk(_head); 159 OrderAccess::release_store(&_head, next); 160 } 161 oop* handle = &_head->_data[_head->_size]; 162 *handle = o; 163 OrderAccess::release_store(&_head->_size, _head->_size + 1); 164 return handle; 165 } 166 167 int ClassLoaderData::ChunkedHandleList::count() const { 168 int count = 0; 169 Chunk* chunk = _head; 170 while (chunk != NULL) { 171 count += chunk->_size; 172 chunk = chunk->_next; 173 } 174 return count; 175 } 176 177 inline void ClassLoaderData::ChunkedHandleList::oops_do_chunk(OopClosure* f, Chunk* c, const juint size) { 178 for (juint i = 0; i < size; i++) { 179 if (c->_data[i] != NULL) { 180 f->do_oop(&c->_data[i]); 181 } 182 } 183 } 184 185 void ClassLoaderData::ChunkedHandleList::oops_do(OopClosure* f) { 186 Chunk* head = OrderAccess::load_acquire(&_head); 187 if (head != NULL) { 188 // Must be careful when reading size of head 189 oops_do_chunk(f, head, OrderAccess::load_acquire(&head->_size)); 190 for (Chunk* c = head->_next; c != NULL; c = c->_next) { 191 oops_do_chunk(f, c, c->_size); 192 } 193 } 194 } 195 196 class VerifyContainsOopClosure : public OopClosure { 197 oop _target; 198 bool _found; 199 200 public: 201 VerifyContainsOopClosure(oop target) : _target(target), _found(false) {} 202 203 void do_oop(oop* p) { 204 if (p != NULL && *p == _target) { 205 _found = true; 206 } 207 } 208 209 void do_oop(narrowOop* p) { 210 // The ChunkedHandleList should not contain any narrowOop 211 ShouldNotReachHere(); 212 } 213 214 bool found() const { 215 return _found; 216 } 217 }; 218 219 bool ClassLoaderData::ChunkedHandleList::contains(oop p) { 220 VerifyContainsOopClosure cl(p); 221 oops_do(&cl); 222 return cl.found(); 223 } 224 225 #ifndef PRODUCT 226 bool ClassLoaderData::ChunkedHandleList::owner_of(oop* oop_handle) { 227 Chunk* chunk = _head; 228 while (chunk != NULL) { 229 if (&(chunk->_data[0]) <= oop_handle && oop_handle < &(chunk->_data[chunk->_size])) { 230 return true; 231 } 232 chunk = chunk->_next; 233 } 234 return false; 235 } 236 #endif // PRODUCT 237 238 bool ClassLoaderData::claim() { 239 if (_claimed == 1) { 240 return false; 241 } 242 243 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0; 244 } 245 246 // Anonymous classes have their own ClassLoaderData that is marked to keep alive 247 // while the class is being parsed, and if the class appears on the module fixup list. 248 // Due to the uniqueness that no other class shares the anonymous class' name or 249 // ClassLoaderData, no other non-GC thread has knowledge of the anonymous class while 250 // it is being defined, therefore _keep_alive is not volatile or atomic. 251 void ClassLoaderData::inc_keep_alive() { 252 if (is_anonymous()) { 253 assert(_keep_alive >= 0, "Invalid keep alive increment count"); 254 _keep_alive++; 255 } 256 } 257 258 void ClassLoaderData::dec_keep_alive() { 259 if (is_anonymous()) { 260 assert(_keep_alive > 0, "Invalid keep alive decrement count"); 261 _keep_alive--; 262 } 263 } 264 265 void ClassLoaderData::oops_do(OopClosure* f, bool must_claim, bool clear_mod_oops) { 266 if (must_claim && !claim()) { 267 return; 268 } 269 270 // Only clear modified_oops after the ClassLoaderData is claimed. 271 if (clear_mod_oops) { 272 clear_modified_oops(); 273 } 274 275 f->do_oop(&_class_loader); 276 _handles.oops_do(f); 277 } 278 279 void ClassLoaderData::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 klass_closure->do_klass(k); 283 assert(k != k->next_link(), "no loops!"); 284 } 285 } 286 287 void ClassLoaderData::classes_do(void f(Klass * const)) { 288 // Lock-free access requires load_acquire 289 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 290 f(k); 291 assert(k != k->next_link(), "no loops!"); 292 } 293 } 294 295 void ClassLoaderData::methods_do(void f(Method*)) { 296 // Lock-free access requires load_acquire 297 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 298 if (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded()) { 299 InstanceKlass::cast(k)->methods_do(f); 300 } 301 } 302 } 303 304 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) { 305 // Lock-free access requires load_acquire 306 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 307 // Do not filter ArrayKlass oops here... 308 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) { 309 klass_closure->do_klass(k); 310 } 311 } 312 } 313 314 void ClassLoaderData::classes_do(void f(InstanceKlass*)) { 315 // Lock-free access requires load_acquire 316 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 317 if (k->is_instance_klass()) { 318 f(InstanceKlass::cast(k)); 319 } 320 assert(k != k->next_link(), "no loops!"); 321 } 322 } 323 324 void ClassLoaderData::modules_do(void f(ModuleEntry*)) { 325 assert_locked_or_safepoint(Module_lock); 326 if (_unnamed_module != NULL) { 327 f(_unnamed_module); 328 } 329 if (_modules != NULL) { 330 for (int i = 0; i < _modules->table_size(); i++) { 331 for (ModuleEntry* entry = _modules->bucket(i); 332 entry != NULL; 333 entry = entry->next()) { 334 f(entry); 335 } 336 } 337 } 338 } 339 340 void ClassLoaderData::packages_do(void f(PackageEntry*)) { 341 assert_locked_or_safepoint(Module_lock); 342 if (_packages != NULL) { 343 for (int i = 0; i < _packages->table_size(); i++) { 344 for (PackageEntry* entry = _packages->bucket(i); 345 entry != NULL; 346 entry = entry->next()) { 347 f(entry); 348 } 349 } 350 } 351 } 352 353 void ClassLoaderData::record_dependency(const Klass* k) { 354 assert(k != NULL, "invariant"); 355 356 ClassLoaderData * const from_cld = this; 357 ClassLoaderData * const to_cld = k->class_loader_data(); 358 359 // Do not need to record dependency if the dependency is to a class whose 360 // class loader data is never freed. (i.e. the dependency's class loader 361 // is one of the three builtin class loaders and the dependency is not 362 // anonymous.) 363 if (to_cld->is_permanent_class_loader_data()) { 364 return; 365 } 366 367 oop to; 368 if (to_cld->is_anonymous()) { 369 // Just return if an anonymous class is attempting to record a dependency 370 // to itself. (Note that every anonymous class has its own unique class 371 // loader data.) 372 if (to_cld == from_cld) { 373 return; 374 } 375 // Anonymous class dependencies are through the mirror. 376 to = k->java_mirror(); 377 } else { 378 to = to_cld->class_loader(); 379 oop from = from_cld->class_loader(); 380 381 // Just return if this dependency is to a class with the same or a parent 382 // class_loader. 383 if (from == to || java_lang_ClassLoader::isAncestor(from, to)) { 384 return; // this class loader is in the parent list, no need to add it. 385 } 386 } 387 388 // It's a dependency we won't find through GC, add it. 389 if (!_handles.contains(to)) { 390 NOT_PRODUCT(Atomic::inc(&_dependency_count)); 391 LogTarget(Trace, class, loader, data) lt; 392 if (lt.is_enabled()) { 393 ResourceMark rm; 394 LogStream ls(lt); 395 ls.print("adding dependency from "); 396 print_value_on(&ls); 397 ls.print(" to "); 398 to_cld->print_value_on(&ls); 399 ls.cr(); 400 } 401 Handle dependency(Thread::current(), to); 402 add_handle(dependency); 403 // Added a potentially young gen oop to the ClassLoaderData 404 record_modified_oops(); 405 } 406 } 407 408 409 void ClassLoaderDataGraph::clear_claimed_marks() { 410 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 411 cld->clear_claimed(); 412 } 413 } 414 415 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) { 416 { 417 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 418 Klass* old_value = _klasses; 419 k->set_next_link(old_value); 420 // Link the new item into the list, making sure the linked class is stable 421 // since the list can be walked without a lock 422 OrderAccess::release_store(&_klasses, k); 423 if (k->is_array_klass()) { 424 ClassLoaderDataGraph::inc_array_classes(1); 425 } else { 426 ClassLoaderDataGraph::inc_instance_classes(1); 427 } 428 } 429 430 if (publicize) { 431 LogTarget(Trace, class, loader, data) lt; 432 if (lt.is_enabled()) { 433 ResourceMark rm; 434 LogStream ls(lt); 435 ls.print("Adding k: " PTR_FORMAT " %s to ", p2i(k), k->external_name()); 436 print_value_on(&ls); 437 ls.cr(); 438 } 439 } 440 } 441 442 // Class iterator used by the compiler. It gets some number of classes at 443 // a safepoint to decay invocation counters on the methods. 444 class ClassLoaderDataGraphKlassIteratorStatic { 445 ClassLoaderData* _current_loader_data; 446 Klass* _current_class_entry; 447 public: 448 449 ClassLoaderDataGraphKlassIteratorStatic() : _current_loader_data(NULL), _current_class_entry(NULL) {} 450 451 InstanceKlass* try_get_next_class() { 452 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 453 size_t max_classes = ClassLoaderDataGraph::num_instance_classes(); 454 assert(max_classes > 0, "should not be called with no instance classes"); 455 for (size_t i = 0; i < max_classes; ) { 456 457 if (_current_class_entry != NULL) { 458 Klass* k = _current_class_entry; 459 _current_class_entry = _current_class_entry->next_link(); 460 461 if (k->is_instance_klass()) { 462 InstanceKlass* ik = InstanceKlass::cast(k); 463 i++; // count all instance classes found 464 // Not yet loaded classes are counted in max_classes 465 // but only return loaded classes. 466 if (ik->is_loaded()) { 467 return ik; 468 } 469 } 470 } else { 471 // Go to next CLD 472 if (_current_loader_data != NULL) { 473 _current_loader_data = _current_loader_data->next(); 474 } 475 // Start at the beginning 476 if (_current_loader_data == NULL) { 477 _current_loader_data = ClassLoaderDataGraph::_head; 478 } 479 480 _current_class_entry = _current_loader_data->klasses(); 481 } 482 } 483 // Should never be reached unless all instance classes have failed or are not fully loaded. 484 // Caller handles NULL. 485 return NULL; 486 } 487 488 // If the current class for the static iterator is a class being unloaded or 489 // deallocated, adjust the current class. 490 void adjust_saved_class(ClassLoaderData* cld) { 491 if (_current_loader_data == cld) { 492 _current_loader_data = cld->next(); 493 if (_current_loader_data != NULL) { 494 _current_class_entry = _current_loader_data->klasses(); 495 } // else try_get_next_class will start at the head 496 } 497 } 498 499 void adjust_saved_class(Klass* klass) { 500 if (_current_class_entry == klass) { 501 _current_class_entry = klass->next_link(); 502 } 503 } 504 }; 505 506 static ClassLoaderDataGraphKlassIteratorStatic static_klass_iterator; 507 508 InstanceKlass* ClassLoaderDataGraph::try_get_next_class() { 509 return static_klass_iterator.try_get_next_class(); 510 } 511 512 513 // Remove a klass from the _klasses list for scratch_class during redefinition 514 // or parsed class in the case of an error. 515 void ClassLoaderData::remove_class(Klass* scratch_class) { 516 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 517 518 // Adjust global class iterator. 519 static_klass_iterator.adjust_saved_class(scratch_class); 520 521 Klass* prev = NULL; 522 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 523 if (k == scratch_class) { 524 if (prev == NULL) { 525 _klasses = k->next_link(); 526 } else { 527 Klass* next = k->next_link(); 528 prev->set_next_link(next); 529 } 530 531 if (k->is_array_klass()) { 532 ClassLoaderDataGraph::dec_array_classes(1); 533 } else { 534 ClassLoaderDataGraph::dec_instance_classes(1); 535 } 536 537 return; 538 } 539 prev = k; 540 assert(k != k->next_link(), "no loops!"); 541 } 542 ShouldNotReachHere(); // should have found this class!! 543 } 544 545 void ClassLoaderData::unload() { 546 _unloading = true; 547 548 // Tell serviceability tools these classes are unloading 549 classes_do(InstanceKlass::notify_unload_class); 550 551 LogTarget(Debug, class, loader, data) lt; 552 if (lt.is_enabled()) { 553 ResourceMark rm; 554 LogStream ls(lt); 555 ls.print("unload "); 556 print_value_on(&ls); 557 ls.cr(); 558 } 559 560 // Some items on the _deallocate_list need to free their C heap structures 561 // if they are not already on the _klasses list. 562 unload_deallocate_list(); 563 564 // Clean up global class iterator for compiler 565 static_klass_iterator.adjust_saved_class(this); 566 } 567 568 ModuleEntryTable* ClassLoaderData::modules() { 569 // Lazily create the module entry table at first request. 570 // Lock-free access requires load_acquire. 571 ModuleEntryTable* modules = OrderAccess::load_acquire(&_modules); 572 if (modules == NULL) { 573 MutexLocker m1(Module_lock); 574 // Check if _modules got allocated while we were waiting for this lock. 575 if ((modules = _modules) == NULL) { 576 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size); 577 578 { 579 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag); 580 // Ensure _modules is stable, since it is examined without a lock 581 OrderAccess::release_store(&_modules, modules); 582 } 583 } 584 } 585 return modules; 586 } 587 588 const int _boot_loader_dictionary_size = 1009; 589 const int _default_loader_dictionary_size = 107; 590 591 Dictionary* ClassLoaderData::create_dictionary() { 592 assert(!is_anonymous(), "anonymous class loader data do not have a dictionary"); 593 int size; 594 bool resizable = false; 595 if (_the_null_class_loader_data == NULL) { 596 size = _boot_loader_dictionary_size; 597 resizable = true; 598 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) { 599 size = 1; // there's only one class in relection class loader and no initiated classes 600 } else if (is_system_class_loader_data()) { 601 size = _boot_loader_dictionary_size; 602 resizable = true; 603 } else { 604 size = _default_loader_dictionary_size; 605 resizable = true; 606 } 607 if (!DynamicallyResizeSystemDictionaries || DumpSharedSpaces || UseSharedSpaces) { 608 resizable = false; 609 } 610 return new Dictionary(this, size, resizable); 611 } 612 613 // Tell the GC to keep this klass alive while iterating ClassLoaderDataGraph 614 oop ClassLoaderData::holder_phantom() { 615 // A klass that was previously considered dead can be looked up in the 616 // CLD/SD, and its _java_mirror or _class_loader can be stored in a root 617 // or a reachable object making it alive again. The SATB part of G1 needs 618 // to get notified about this potential resurrection, otherwise the marking 619 // might not find the object. 620 if (!keep_alive()) { 621 oop* o = is_anonymous() ? _klasses->java_mirror_handle().ptr_raw() : &_class_loader; 622 return RootAccess<ON_PHANTOM_OOP_REF>::oop_load(o); 623 } else { 624 return NULL; 625 } 626 } 627 628 // Unloading support 629 oop ClassLoaderData::keep_alive_object() const { 630 assert_locked_or_safepoint(_metaspace_lock); 631 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive"); 632 return is_anonymous() ? _klasses->java_mirror() : class_loader(); 633 } 634 635 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const { 636 bool alive = keep_alive() // null class loader and incomplete anonymous klasses. 637 || is_alive_closure->do_object_b(keep_alive_object()); 638 639 return alive; 640 } 641 642 class ReleaseKlassClosure: public KlassClosure { 643 private: 644 size_t _instance_class_released; 645 size_t _array_class_released; 646 public: 647 ReleaseKlassClosure() : _instance_class_released(0), _array_class_released(0) { } 648 649 size_t instance_class_released() const { return _instance_class_released; } 650 size_t array_class_released() const { return _array_class_released; } 651 652 void do_klass(Klass* k) { 653 if (k->is_array_klass()) { 654 _array_class_released ++; 655 } else { 656 assert(k->is_instance_klass(), "Must be"); 657 _instance_class_released ++; 658 InstanceKlass::release_C_heap_structures(InstanceKlass::cast(k)); 659 } 660 } 661 }; 662 663 ClassLoaderData::~ClassLoaderData() { 664 // Release C heap structures for all the classes. 665 ReleaseKlassClosure cl; 666 classes_do(&cl); 667 668 ClassLoaderDataGraph::dec_array_classes(cl.array_class_released()); 669 ClassLoaderDataGraph::dec_instance_classes(cl.instance_class_released()); 670 671 // Release C heap allocated hashtable for all the packages. 672 if (_packages != NULL) { 673 // Destroy the table itself 674 delete _packages; 675 _packages = NULL; 676 } 677 678 // Release C heap allocated hashtable for all the modules. 679 if (_modules != NULL) { 680 // Destroy the table itself 681 delete _modules; 682 _modules = NULL; 683 } 684 685 // Release C heap allocated hashtable for the dictionary 686 if (_dictionary != NULL) { 687 // Destroy the table itself 688 delete _dictionary; 689 _dictionary = NULL; 690 } 691 692 if (_unnamed_module != NULL) { 693 _unnamed_module->delete_unnamed_module(); 694 _unnamed_module = NULL; 695 } 696 697 // release the metaspace 698 ClassLoaderMetaspace *m = _metaspace; 699 if (m != NULL) { 700 _metaspace = NULL; 701 delete m; 702 } 703 // Clear all the JNI handles for methods 704 // These aren't deallocated and are going to look like a leak, but that's 705 // needed because we can't really get rid of jmethodIDs because we don't 706 // know when native code is going to stop using them. The spec says that 707 // they're "invalid" but existing programs likely rely on their being 708 // NULL after class unloading. 709 if (_jmethod_ids != NULL) { 710 Method::clear_jmethod_ids(this); 711 } 712 // Delete lock 713 delete _metaspace_lock; 714 715 // Delete free list 716 if (_deallocate_list != NULL) { 717 delete _deallocate_list; 718 } 719 } 720 721 // Returns true if this class loader data is for the app class loader 722 // or a user defined system class loader. (Note that the class loader 723 // data may be anonymous.) 724 bool ClassLoaderData::is_system_class_loader_data() const { 725 return SystemDictionary::is_system_class_loader(class_loader()); 726 } 727 728 // Returns true if this class loader data is for the platform class loader. 729 // (Note that the class loader data may be anonymous.) 730 bool ClassLoaderData::is_platform_class_loader_data() const { 731 return SystemDictionary::is_platform_class_loader(class_loader()); 732 } 733 734 // Returns true if the class loader for this class loader data is one of 735 // the 3 builtin (boot application/system or platform) class loaders, 736 // including a user-defined system class loader. Note that if the class 737 // loader data is for an anonymous class then it may get freed by a GC 738 // even if its class loader is one of these loaders. 739 bool ClassLoaderData::is_builtin_class_loader_data() const { 740 return (is_boot_class_loader_data() || 741 SystemDictionary::is_system_class_loader(class_loader()) || 742 SystemDictionary::is_platform_class_loader(class_loader())); 743 } 744 745 // Returns true if this class loader data is a class loader data 746 // that is not ever freed by a GC. It must be one of the builtin 747 // class loaders and not anonymous. 748 bool ClassLoaderData::is_permanent_class_loader_data() const { 749 return is_builtin_class_loader_data() && !is_anonymous(); 750 } 751 752 ClassLoaderMetaspace* ClassLoaderData::metaspace_non_null() { 753 // If the metaspace has not been allocated, create a new one. Might want 754 // to create smaller arena for Reflection class loaders also. 755 // The reason for the delayed allocation is because some class loaders are 756 // simply for delegating with no metadata of their own. 757 // Lock-free access requires load_acquire. 758 ClassLoaderMetaspace* metaspace = OrderAccess::load_acquire(&_metaspace); 759 if (metaspace == NULL) { 760 MutexLockerEx ml(_metaspace_lock, Mutex::_no_safepoint_check_flag); 761 // Check if _metaspace got allocated while we were waiting for this lock. 762 if ((metaspace = _metaspace) == NULL) { 763 if (this == the_null_class_loader_data()) { 764 assert (class_loader() == NULL, "Must be"); 765 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::BootMetaspaceType); 766 } else if (is_anonymous()) { 767 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType); 768 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) { 769 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType); 770 } else { 771 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::StandardMetaspaceType); 772 } 773 // Ensure _metaspace is stable, since it is examined without a lock 774 OrderAccess::release_store(&_metaspace, metaspace); 775 } 776 } 777 return metaspace; 778 } 779 780 OopHandle ClassLoaderData::add_handle(Handle h) { 781 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 782 record_modified_oops(); 783 return OopHandle(_handles.add(h())); 784 } 785 786 void ClassLoaderData::remove_handle(OopHandle h) { 787 assert(!is_unloading(), "Do not remove a handle for a CLD that is unloading"); 788 oop* ptr = h.ptr_raw(); 789 if (ptr != NULL) { 790 assert(_handles.owner_of(ptr), "Got unexpected handle " PTR_FORMAT, p2i(ptr)); 791 // This root is not walked in safepoints, and hence requires an appropriate 792 // decorator that e.g. maintains the SATB invariant in SATB collectors. 793 RootAccess<IN_CONCURRENT_ROOT>::oop_store(ptr, oop(NULL)); 794 } 795 } 796 797 void ClassLoaderData::init_handle_locked(OopHandle& dest, Handle h) { 798 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 799 if (dest.resolve() != NULL) { 800 return; 801 } else { 802 dest = _handles.add(h()); 803 } 804 } 805 806 // Add this metadata pointer to be freed when it's safe. This is only during 807 // class unloading because Handles might point to this metadata field. 808 void ClassLoaderData::add_to_deallocate_list(Metadata* m) { 809 // Metadata in shared region isn't deleted. 810 if (!m->is_shared()) { 811 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 812 if (_deallocate_list == NULL) { 813 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true); 814 } 815 _deallocate_list->append_if_missing(m); 816 } 817 } 818 819 // Deallocate free metadata on the free list. How useful the PermGen was! 820 void ClassLoaderData::free_deallocate_list() { 821 // Don't need lock, at safepoint 822 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 823 assert(!is_unloading(), "only called for ClassLoaderData that are not unloading"); 824 if (_deallocate_list == NULL) { 825 return; 826 } 827 // Go backwards because this removes entries that are freed. 828 for (int i = _deallocate_list->length() - 1; i >= 0; i--) { 829 Metadata* m = _deallocate_list->at(i); 830 if (!m->on_stack()) { 831 _deallocate_list->remove_at(i); 832 // There are only three types of metadata that we deallocate directly. 833 // Cast them so they can be used by the template function. 834 if (m->is_method()) { 835 MetadataFactory::free_metadata(this, (Method*)m); 836 } else if (m->is_constantPool()) { 837 MetadataFactory::free_metadata(this, (ConstantPool*)m); 838 } else if (m->is_klass()) { 839 MetadataFactory::free_metadata(this, (InstanceKlass*)m); 840 } else { 841 ShouldNotReachHere(); 842 } 843 } else { 844 // Metadata is alive. 845 // If scratch_class is on stack then it shouldn't be on this list! 846 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(), 847 "scratch classes on this list should be dead"); 848 // Also should assert that other metadata on the list was found in handles. 849 } 850 } 851 } 852 853 // This is distinct from free_deallocate_list. For class loader data that are 854 // unloading, this frees the C heap memory for items on the list, and unlinks 855 // scratch or error classes so that unloading events aren't triggered for these 856 // classes. The metadata is removed with the unloading metaspace. 857 // There isn't C heap memory allocated for methods, so nothing is done for them. 858 void ClassLoaderData::unload_deallocate_list() { 859 // Don't need lock, at safepoint 860 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 861 assert(is_unloading(), "only called for ClassLoaderData that are unloading"); 862 if (_deallocate_list == NULL) { 863 return; 864 } 865 // Go backwards because this removes entries that are freed. 866 for (int i = _deallocate_list->length() - 1; i >= 0; i--) { 867 Metadata* m = _deallocate_list->at(i); 868 assert (!m->on_stack(), "wouldn't be unloading if this were so"); 869 _deallocate_list->remove_at(i); 870 if (m->is_constantPool()) { 871 ((ConstantPool*)m)->release_C_heap_structures(); 872 } else if (m->is_klass()) { 873 InstanceKlass* ik = (InstanceKlass*)m; 874 // also releases ik->constants() C heap memory 875 InstanceKlass::release_C_heap_structures(ik); 876 // Remove the class so unloading events aren't triggered for 877 // this class (scratch or error class) in do_unloading(). 878 remove_class(ik); 879 } 880 } 881 } 882 883 // These anonymous class loaders are to contain classes used for JSR292 884 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(Handle loader) { 885 // Add a new class loader data to the graph. 886 return ClassLoaderDataGraph::add(loader, true); 887 } 888 889 const char* ClassLoaderData::loader_name() const { 890 // Handles null class loader 891 return SystemDictionary::loader_name(class_loader()); 892 } 893 894 895 void ClassLoaderData::print_value_on(outputStream* out) const { 896 if (class_loader() != NULL) { 897 out->print("loader data: " INTPTR_FORMAT " for instance ", p2i(this)); 898 class_loader()->print_value_on(out); // includes loader_name() and address of class loader instance 899 } else { 900 // loader data: 0xsomeaddr of <bootloader> 901 out->print("loader data: " INTPTR_FORMAT " of %s", p2i(this), loader_name()); 902 } 903 if (is_anonymous()) { 904 out->print(" anonymous"); 905 } 906 } 907 908 #ifndef PRODUCT 909 void ClassLoaderData::print_on(outputStream* out) const { 910 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: %s {", 911 p2i(this), p2i((void *)class_loader()), loader_name()); 912 if (is_anonymous()) out->print(" anonymous"); 913 if (claimed()) out->print(" claimed"); 914 if (is_unloading()) out->print(" unloading"); 915 out->print(" metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null())); 916 917 if (_jmethod_ids != NULL) { 918 Method::print_jmethod_ids(this, out); 919 } 920 out->print(" handles count %d", _handles.count()); 921 out->print(" dependencies %d", _dependency_count); 922 out->print_cr("}"); 923 } 924 #endif // PRODUCT 925 926 void ClassLoaderData::verify() { 927 assert_locked_or_safepoint(_metaspace_lock); 928 oop cl = class_loader(); 929 930 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same"); 931 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be"); 932 933 // Verify the integrity of the allocated space. 934 if (metaspace_or_null() != NULL) { 935 metaspace_or_null()->verify(); 936 } 937 938 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 939 guarantee(k->class_loader_data() == this, "Must be the same"); 940 k->verify(); 941 assert(k != k->next_link(), "no loops!"); 942 } 943 } 944 945 bool ClassLoaderData::contains_klass(Klass* klass) { 946 // Lock-free access requires load_acquire 947 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 948 if (k == klass) return true; 949 } 950 return false; 951 } 952 953 954 // GC root of class loader data created. 955 ClassLoaderData* ClassLoaderDataGraph::_head = NULL; 956 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL; 957 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL; 958 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL; 959 960 bool ClassLoaderDataGraph::_should_purge = false; 961 bool ClassLoaderDataGraph::_metaspace_oom = false; 962 963 // Add a new class loader data node to the list. Assign the newly created 964 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field 965 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous) { 966 NoSafepointVerifier no_safepoints; // we mustn't GC until we've installed the 967 // ClassLoaderData in the graph since the CLD 968 // contains unhandled oops 969 970 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous); 971 972 973 if (!is_anonymous) { 974 // First, Atomically set it 975 ClassLoaderData* old = java_lang_ClassLoader::cmpxchg_loader_data(cld, loader(), NULL); 976 if (old != NULL) { 977 delete cld; 978 // Returns the data. 979 return old; 980 } 981 } 982 983 // We won the race, and therefore the task of adding the data to the list of 984 // class loader data 985 ClassLoaderData** list_head = &_head; 986 ClassLoaderData* next = _head; 987 988 do { 989 cld->set_next(next); 990 ClassLoaderData* exchanged = Atomic::cmpxchg(cld, list_head, next); 991 if (exchanged == next) { 992 LogTarget(Debug, class, loader, data) lt; 993 if (lt.is_enabled()) { 994 ResourceMark rm; 995 LogStream ls(lt); 996 ls.print("create "); 997 cld->print_value_on(&ls); 998 ls.cr(); 999 } 1000 return cld; 1001 } 1002 next = exchanged; 1003 } while (true); 1004 } 1005 1006 void ClassLoaderDataGraph::oops_do(OopClosure* f, bool must_claim) { 1007 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 1008 cld->oops_do(f, must_claim); 1009 } 1010 } 1011 1012 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, bool must_claim) { 1013 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 1014 if (cld->keep_alive()) { 1015 cld->oops_do(f, must_claim); 1016 } 1017 } 1018 } 1019 1020 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, bool must_claim) { 1021 if (ClassUnloading) { 1022 keep_alive_oops_do(f, must_claim); 1023 } else { 1024 oops_do(f, must_claim); 1025 } 1026 } 1027 1028 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) { 1029 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) { 1030 cl->do_cld(cld); 1031 } 1032 } 1033 1034 void ClassLoaderDataGraph::cld_unloading_do(CLDClosure* cl) { 1035 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 1036 // Only walk the head until any clds not purged from prior unloading 1037 // (CMS doesn't purge right away). 1038 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) { 1039 assert(cld->is_unloading(), "invariant"); 1040 cl->do_cld(cld); 1041 } 1042 } 1043 1044 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) { 1045 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) { 1046 CLDClosure* closure = cld->keep_alive() ? strong : weak; 1047 if (closure != NULL) { 1048 closure->do_cld(cld); 1049 } 1050 } 1051 } 1052 1053 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) { 1054 roots_cld_do(cl, NULL); 1055 } 1056 1057 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) { 1058 if (ClassUnloading) { 1059 keep_alive_cld_do(cl); 1060 } else { 1061 cld_do(cl); 1062 } 1063 } 1064 1065 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) { 1066 Thread* thread = Thread::current(); 1067 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 1068 Handle holder(thread, cld->holder_phantom()); 1069 cld->classes_do(klass_closure); 1070 } 1071 } 1072 1073 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) { 1074 Thread* thread = Thread::current(); 1075 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 1076 Handle holder(thread, cld->holder_phantom()); 1077 cld->classes_do(f); 1078 } 1079 } 1080 1081 void ClassLoaderDataGraph::methods_do(void f(Method*)) { 1082 Thread* thread = Thread::current(); 1083 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 1084 Handle holder(thread, cld->holder_phantom()); 1085 cld->methods_do(f); 1086 } 1087 } 1088 1089 void ClassLoaderDataGraph::modules_do(void f(ModuleEntry*)) { 1090 assert_locked_or_safepoint(Module_lock); 1091 Thread* thread = Thread::current(); 1092 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 1093 Handle holder(thread, cld->holder_phantom()); 1094 cld->modules_do(f); 1095 } 1096 } 1097 1098 void ClassLoaderDataGraph::modules_unloading_do(void f(ModuleEntry*)) { 1099 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 1100 // Only walk the head until any clds not purged from prior unloading 1101 // (CMS doesn't purge right away). 1102 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) { 1103 assert(cld->is_unloading(), "invariant"); 1104 cld->modules_do(f); 1105 } 1106 } 1107 1108 void ClassLoaderDataGraph::packages_do(void f(PackageEntry*)) { 1109 assert_locked_or_safepoint(Module_lock); 1110 Thread* thread = Thread::current(); 1111 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 1112 Handle holder(thread, cld->holder_phantom()); 1113 cld->packages_do(f); 1114 } 1115 } 1116 1117 void ClassLoaderDataGraph::packages_unloading_do(void f(PackageEntry*)) { 1118 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 1119 // Only walk the head until any clds not purged from prior unloading 1120 // (CMS doesn't purge right away). 1121 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) { 1122 assert(cld->is_unloading(), "invariant"); 1123 cld->packages_do(f); 1124 } 1125 } 1126 1127 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) { 1128 Thread* thread = Thread::current(); 1129 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 1130 Handle holder(thread, cld->holder_phantom()); 1131 cld->loaded_classes_do(klass_closure); 1132 } 1133 } 1134 1135 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) { 1136 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 1137 // Only walk the head until any clds not purged from prior unloading 1138 // (CMS doesn't purge right away). 1139 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) { 1140 assert(cld->is_unloading(), "invariant"); 1141 cld->classes_do(f); 1142 } 1143 } 1144 1145 #define FOR_ALL_DICTIONARY(X) for (ClassLoaderData* X = _head; X != NULL; X = X->next()) \ 1146 if (X->dictionary() != NULL) 1147 1148 // Walk classes in the loaded class dictionaries in various forms. 1149 // Only walks the classes defined in this class loader. 1150 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*)) { 1151 Thread* thread = Thread::current(); 1152 FOR_ALL_DICTIONARY(cld) { 1153 Handle holder(thread, cld->holder_phantom()); 1154 cld->dictionary()->classes_do(f); 1155 } 1156 } 1157 1158 // Only walks the classes defined in this class loader. 1159 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*, TRAPS), TRAPS) { 1160 Thread* thread = Thread::current(); 1161 FOR_ALL_DICTIONARY(cld) { 1162 Handle holder(thread, cld->holder_phantom()); 1163 cld->dictionary()->classes_do(f, CHECK); 1164 } 1165 } 1166 1167 // Walks all entries in the dictionary including entries initiated by this class loader. 1168 void ClassLoaderDataGraph::dictionary_all_entries_do(void f(InstanceKlass*, ClassLoaderData*)) { 1169 Thread* thread = Thread::current(); 1170 FOR_ALL_DICTIONARY(cld) { 1171 Handle holder(thread, cld->holder_phantom()); 1172 cld->dictionary()->all_entries_do(f); 1173 } 1174 } 1175 1176 void ClassLoaderDataGraph::verify_dictionary() { 1177 FOR_ALL_DICTIONARY(cld) { 1178 cld->dictionary()->verify(); 1179 } 1180 } 1181 1182 void ClassLoaderDataGraph::print_dictionary(outputStream* st) { 1183 FOR_ALL_DICTIONARY(cld) { 1184 st->print("Dictionary for "); 1185 cld->print_value_on(st); 1186 st->cr(); 1187 cld->dictionary()->print_on(st); 1188 st->cr(); 1189 } 1190 } 1191 1192 void ClassLoaderDataGraph::print_dictionary_statistics(outputStream* st) { 1193 FOR_ALL_DICTIONARY(cld) { 1194 ResourceMark rm; 1195 stringStream tempst; 1196 tempst.print("System Dictionary for %s", cld->loader_name()); 1197 cld->dictionary()->print_table_statistics(st, tempst.as_string()); 1198 } 1199 } 1200 1201 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() { 1202 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?"); 1203 1204 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>(); 1205 1206 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true); 1207 ClassLoaderData* curr = _head; 1208 while (curr != _saved_head) { 1209 if (!curr->claimed()) { 1210 array->push(curr); 1211 LogTarget(Debug, class, loader, data) lt; 1212 if (lt.is_enabled()) { 1213 LogStream ls(lt); 1214 ls.print("found new CLD: "); 1215 curr->print_value_on(&ls); 1216 ls.cr(); 1217 } 1218 } 1219 1220 curr = curr->_next; 1221 } 1222 1223 return array; 1224 } 1225 1226 #ifndef PRODUCT 1227 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) { 1228 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 1229 if (loader_data == data) { 1230 return true; 1231 } 1232 } 1233 1234 return false; 1235 } 1236 #endif // PRODUCT 1237 1238 1239 // Move class loader data from main list to the unloaded list for unloading 1240 // and deallocation later. 1241 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure, 1242 bool clean_previous_versions) { 1243 1244 ClassLoaderData* data = _head; 1245 ClassLoaderData* prev = NULL; 1246 bool seen_dead_loader = false; 1247 1248 // Mark metadata seen on the stack only so we can delete unneeded entries. 1249 // Only walk all metadata, including the expensive code cache walk, for Full GC 1250 // and only if class redefinition and if there's previous versions of 1251 // Klasses to delete. 1252 bool walk_all_metadata = clean_previous_versions && 1253 JvmtiExport::has_redefined_a_class() && 1254 InstanceKlass::has_previous_versions_and_reset(); 1255 MetadataOnStackMark md_on_stack(walk_all_metadata); 1256 1257 // Save previous _unloading pointer for CMS which may add to unloading list before 1258 // purging and we don't want to rewalk the previously unloaded class loader data. 1259 _saved_unloading = _unloading; 1260 1261 data = _head; 1262 while (data != NULL) { 1263 if (data->is_alive(is_alive_closure)) { 1264 // clean metaspace 1265 if (walk_all_metadata) { 1266 data->classes_do(InstanceKlass::purge_previous_versions); 1267 } 1268 data->free_deallocate_list(); 1269 prev = data; 1270 data = data->next(); 1271 continue; 1272 } 1273 seen_dead_loader = true; 1274 ClassLoaderData* dead = data; 1275 dead->unload(); 1276 data = data->next(); 1277 // Remove from loader list. 1278 // This class loader data will no longer be found 1279 // in the ClassLoaderDataGraph. 1280 if (prev != NULL) { 1281 prev->set_next(data); 1282 } else { 1283 assert(dead == _head, "sanity check"); 1284 _head = data; 1285 } 1286 dead->set_next(_unloading); 1287 _unloading = dead; 1288 } 1289 1290 if (seen_dead_loader) { 1291 data = _head; 1292 while (data != NULL) { 1293 // Remove entries in the dictionary of live class loader that have 1294 // initiated loading classes in a dead class loader. 1295 if (data->dictionary() != NULL) { 1296 data->dictionary()->do_unloading(is_alive_closure); 1297 } 1298 // Walk a ModuleEntry's reads, and a PackageEntry's exports 1299 // lists to determine if there are modules on those lists that are now 1300 // dead and should be removed. A module's life cycle is equivalent 1301 // to its defining class loader's life cycle. Since a module is 1302 // considered dead if its class loader is dead, these walks must 1303 // occur after each class loader's aliveness is determined. 1304 if (data->packages() != NULL) { 1305 data->packages()->purge_all_package_exports(); 1306 } 1307 if (data->modules_defined()) { 1308 data->modules()->purge_all_module_reads(); 1309 } 1310 data = data->next(); 1311 } 1312 1313 post_class_unload_events(); 1314 } 1315 1316 return seen_dead_loader; 1317 } 1318 1319 void ClassLoaderDataGraph::purge() { 1320 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 1321 ClassLoaderData* list = _unloading; 1322 _unloading = NULL; 1323 ClassLoaderData* next = list; 1324 bool classes_unloaded = false; 1325 while (next != NULL) { 1326 ClassLoaderData* purge_me = next; 1327 next = purge_me->next(); 1328 delete purge_me; 1329 classes_unloaded = true; 1330 } 1331 if (classes_unloaded) { 1332 Metaspace::purge(); 1333 set_metaspace_oom(false); 1334 } 1335 } 1336 1337 int ClassLoaderDataGraph::resize_if_needed() { 1338 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 1339 int resized = 0; 1340 if (Dictionary::does_any_dictionary_needs_resizing()) { 1341 FOR_ALL_DICTIONARY(cld) { 1342 if (cld->dictionary()->resize_if_needed()) { 1343 resized++; 1344 } 1345 } 1346 } 1347 return resized; 1348 } 1349 1350 void ClassLoaderDataGraph::post_class_unload_events() { 1351 #if INCLUDE_TRACE 1352 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 1353 if (Tracing::enabled()) { 1354 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) { 1355 assert(_unloading != NULL, "need class loader data unload list!"); 1356 _class_unload_time = Ticks::now(); 1357 classes_unloading_do(&class_unload_event); 1358 } 1359 Tracing::on_unloading_classes(); 1360 } 1361 #endif 1362 } 1363 1364 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic() 1365 : _next_klass(NULL) { 1366 ClassLoaderData* cld = ClassLoaderDataGraph::_head; 1367 Klass* klass = NULL; 1368 1369 // Find the first klass in the CLDG. 1370 while (cld != NULL) { 1371 assert_locked_or_safepoint(cld->metaspace_lock()); 1372 klass = cld->_klasses; 1373 if (klass != NULL) { 1374 _next_klass = klass; 1375 return; 1376 } 1377 cld = cld->next(); 1378 } 1379 } 1380 1381 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) { 1382 Klass* next = klass->next_link(); 1383 if (next != NULL) { 1384 return next; 1385 } 1386 1387 // No more klasses in the current CLD. Time to find a new CLD. 1388 ClassLoaderData* cld = klass->class_loader_data(); 1389 assert_locked_or_safepoint(cld->metaspace_lock()); 1390 while (next == NULL) { 1391 cld = cld->next(); 1392 if (cld == NULL) { 1393 break; 1394 } 1395 next = cld->_klasses; 1396 } 1397 1398 return next; 1399 } 1400 1401 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() { 1402 Klass* head = _next_klass; 1403 1404 while (head != NULL) { 1405 Klass* next = next_klass_in_cldg(head); 1406 1407 Klass* old_head = Atomic::cmpxchg(next, &_next_klass, head); 1408 1409 if (old_head == head) { 1410 return head; // Won the CAS. 1411 } 1412 1413 head = old_head; 1414 } 1415 1416 // Nothing more for the iterator to hand out. 1417 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head)); 1418 return NULL; 1419 } 1420 1421 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() { 1422 _data = ClassLoaderDataGraph::_head; 1423 } 1424 1425 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {} 1426 1427 #ifndef PRODUCT 1428 // callable from debugger 1429 extern "C" int print_loader_data_graph() { 1430 ResourceMark rm; 1431 ClassLoaderDataGraph::print_on(tty); 1432 return 0; 1433 } 1434 1435 void ClassLoaderDataGraph::verify() { 1436 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 1437 data->verify(); 1438 } 1439 } 1440 1441 void ClassLoaderDataGraph::print_on(outputStream * const out) { 1442 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 1443 data->print_on(out); 1444 } 1445 } 1446 #endif // PRODUCT 1447 1448 #if INCLUDE_TRACE 1449 1450 Ticks ClassLoaderDataGraph::_class_unload_time; 1451 1452 void ClassLoaderDataGraph::class_unload_event(Klass* const k) { 1453 assert(k != NULL, "invariant"); 1454 1455 // post class unload event 1456 EventClassUnload event(UNTIMED); 1457 event.set_endtime(_class_unload_time); 1458 event.set_unloadedClass(k); 1459 event.set_definingClassLoader(k->class_loader_data()); 1460 event.commit(); 1461 } 1462 1463 #endif // INCLUDE_TRACE