1 /* 2 * Copyright (c) 2012, 2017, 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 "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_TRACE 79 #include "trace/tracing.hpp" 80 #endif 81 82 // helper function to avoid in-line casts 83 template <typename T> static T* load_ptr_acquire(T* volatile *p) { 84 return static_cast<T*>(OrderAccess::load_ptr_acquire(p)); 85 } 86 87 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL; 88 89 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous, Dependencies dependencies) : 90 _class_loader(h_class_loader()), 91 _is_anonymous(is_anonymous), 92 // An anonymous class loader data doesn't have anything to keep 93 // it from being unloaded during parsing of the anonymous class. 94 // The null-class-loader should always be kept alive. 95 _keep_alive((is_anonymous || h_class_loader.is_null()) ? 1 : 0), 96 _metaspace(NULL), _unloading(false), _klasses(NULL), 97 _modules(NULL), _packages(NULL), 98 _claimed(0), _jmethod_ids(NULL), _handles(), _deallocate_list(NULL), 99 _next(NULL), _dependencies(dependencies), 100 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true, 101 Monitor::_safepoint_check_never)) { 102 103 // A ClassLoaderData created solely for an anonymous class should never have a 104 // ModuleEntryTable or PackageEntryTable created for it. The defining package 105 // and module for an anonymous class will be found in its host class. 106 if (!is_anonymous) { 107 _packages = new PackageEntryTable(PackageEntryTable::_packagetable_entry_size); 108 if (h_class_loader.is_null()) { 109 // Create unnamed module for boot loader 110 _unnamed_module = ModuleEntry::create_boot_unnamed_module(this); 111 } else { 112 // Create unnamed module for all other loaders 113 _unnamed_module = ModuleEntry::create_unnamed_module(this); 114 } 115 } else { 116 _unnamed_module = NULL; 117 } 118 119 if (!is_anonymous) { 120 _dictionary = create_dictionary(); 121 } else { 122 _dictionary = NULL; 123 } 124 TRACE_INIT_ID(this); 125 } 126 127 void ClassLoaderData::init_dependencies(TRAPS) { 128 assert(!Universe::is_fully_initialized(), "should only be called when initializing"); 129 assert(is_the_null_class_loader_data(), "should only call this for the null class loader"); 130 _dependencies.init(CHECK); 131 } 132 133 void ClassLoaderData::Dependencies::init(TRAPS) { 134 // Create empty dependencies array to add to. CMS requires this to be 135 // an oop so that it can track additions via card marks. We think. 136 _list_head = oopFactory::new_objectArray(2, CHECK); 137 } 138 139 ClassLoaderData::ChunkedHandleList::~ChunkedHandleList() { 140 Chunk* c = _head; 141 while (c != NULL) { 142 Chunk* next = c->_next; 143 delete c; 144 c = next; 145 } 146 } 147 148 oop* ClassLoaderData::ChunkedHandleList::add(oop o) { 149 if (_head == NULL || _head->_size == Chunk::CAPACITY) { 150 Chunk* next = new Chunk(_head); 151 OrderAccess::release_store_ptr(&_head, next); 152 } 153 oop* handle = &_head->_data[_head->_size]; 154 *handle = o; 155 OrderAccess::release_store(&_head->_size, _head->_size + 1); 156 return handle; 157 } 158 159 inline void ClassLoaderData::ChunkedHandleList::oops_do_chunk(OopClosure* f, Chunk* c, const juint size) { 160 for (juint i = 0; i < size; i++) { 161 if (c->_data[i] != NULL) { 162 f->do_oop(&c->_data[i]); 163 } 164 } 165 } 166 167 void ClassLoaderData::ChunkedHandleList::oops_do(OopClosure* f) { 168 Chunk* head = (Chunk*) OrderAccess::load_ptr_acquire(&_head); 169 if (head != NULL) { 170 // Must be careful when reading size of head 171 oops_do_chunk(f, head, OrderAccess::load_acquire(&head->_size)); 172 for (Chunk* c = head->_next; c != NULL; c = c->_next) { 173 oops_do_chunk(f, c, c->_size); 174 } 175 } 176 } 177 178 #ifdef ASSERT 179 class VerifyContainsOopClosure : public OopClosure { 180 oop* _target; 181 bool _found; 182 183 public: 184 VerifyContainsOopClosure(oop* target) : _target(target), _found(false) {} 185 186 void do_oop(oop* p) { 187 if (p == _target) { 188 _found = true; 189 } 190 } 191 192 void do_oop(narrowOop* p) { 193 // The ChunkedHandleList should not contain any narrowOop 194 ShouldNotReachHere(); 195 } 196 197 bool found() const { 198 return _found; 199 } 200 }; 201 202 bool ClassLoaderData::ChunkedHandleList::contains(oop* p) { 203 VerifyContainsOopClosure cl(p); 204 oops_do(&cl); 205 return cl.found(); 206 } 207 #endif 208 209 bool ClassLoaderData::claim() { 210 if (_claimed == 1) { 211 return false; 212 } 213 214 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0; 215 } 216 217 // Anonymous classes have their own ClassLoaderData that is marked to keep alive 218 // while the class is being parsed, and if the class appears on the module fixup list. 219 // Due to the uniqueness that no other class shares the anonymous class' name or 220 // ClassLoaderData, no other non-GC thread has knowledge of the anonymous class while 221 // it is being defined, therefore _keep_alive is not volatile or atomic. 222 void ClassLoaderData::inc_keep_alive() { 223 if (is_anonymous()) { 224 assert(_keep_alive >= 0, "Invalid keep alive increment count"); 225 _keep_alive++; 226 } 227 } 228 229 void ClassLoaderData::dec_keep_alive() { 230 if (is_anonymous()) { 231 assert(_keep_alive > 0, "Invalid keep alive decrement count"); 232 _keep_alive--; 233 } 234 } 235 236 void ClassLoaderData::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 237 if (must_claim && !claim()) { 238 return; 239 } 240 241 f->do_oop(&_class_loader); 242 _dependencies.oops_do(f); 243 244 _handles.oops_do(f); 245 246 if (klass_closure != NULL) { 247 classes_do(klass_closure); 248 } 249 } 250 251 void ClassLoaderData::Dependencies::oops_do(OopClosure* f) { 252 f->do_oop((oop*)&_list_head); 253 } 254 255 void ClassLoaderData::classes_do(KlassClosure* klass_closure) { 256 // Lock-free access requires load_ptr_acquire 257 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) { 258 klass_closure->do_klass(k); 259 assert(k != k->next_link(), "no loops!"); 260 } 261 } 262 263 void ClassLoaderData::classes_do(void f(Klass * const)) { 264 // Lock-free access requires load_ptr_acquire 265 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) { 266 f(k); 267 assert(k != k->next_link(), "no loops!"); 268 } 269 } 270 271 void ClassLoaderData::methods_do(void f(Method*)) { 272 // Lock-free access requires load_ptr_acquire 273 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) { 274 if (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded()) { 275 InstanceKlass::cast(k)->methods_do(f); 276 } 277 } 278 } 279 280 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) { 281 // Lock-free access requires load_ptr_acquire 282 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) { 283 // Do not filter ArrayKlass oops here... 284 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) { 285 klass_closure->do_klass(k); 286 } 287 } 288 } 289 290 void ClassLoaderData::classes_do(void f(InstanceKlass*)) { 291 // Lock-free access requires load_ptr_acquire 292 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) { 293 if (k->is_instance_klass()) { 294 f(InstanceKlass::cast(k)); 295 } 296 assert(k != k->next_link(), "no loops!"); 297 } 298 } 299 300 void ClassLoaderData::modules_do(void f(ModuleEntry*)) { 301 assert_locked_or_safepoint(Module_lock); 302 if (_unnamed_module != NULL) { 303 f(_unnamed_module); 304 } 305 if (_modules != NULL) { 306 for (int i = 0; i < _modules->table_size(); i++) { 307 for (ModuleEntry* entry = _modules->bucket(i); 308 entry != NULL; 309 entry = entry->next()) { 310 f(entry); 311 } 312 } 313 } 314 } 315 316 void ClassLoaderData::packages_do(void f(PackageEntry*)) { 317 assert_locked_or_safepoint(Module_lock); 318 if (_packages != NULL) { 319 for (int i = 0; i < _packages->table_size(); i++) { 320 for (PackageEntry* entry = _packages->bucket(i); 321 entry != NULL; 322 entry = entry->next()) { 323 f(entry); 324 } 325 } 326 } 327 } 328 329 void ClassLoaderData::record_dependency(const Klass* k, TRAPS) { 330 assert(k != NULL, "invariant"); 331 332 ClassLoaderData * const from_cld = this; 333 ClassLoaderData * const to_cld = k->class_loader_data(); 334 335 // Dependency to the null class loader data doesn't need to be recorded 336 // because the null class loader data never goes away. 337 if (to_cld->is_the_null_class_loader_data()) { 338 return; 339 } 340 341 oop to; 342 if (to_cld->is_anonymous()) { 343 // Anonymous class dependencies are through the mirror. 344 to = k->java_mirror(); 345 } else { 346 to = to_cld->class_loader(); 347 348 // If from_cld is anonymous, even if it's class_loader is a parent of 'to' 349 // we still have to add it. The class_loader won't keep from_cld alive. 350 if (!from_cld->is_anonymous()) { 351 // Check that this dependency isn't from the same or parent class_loader 352 oop from = from_cld->class_loader(); 353 354 oop curr = from; 355 while (curr != NULL) { 356 if (curr == to) { 357 return; // this class loader is in the parent list, no need to add it. 358 } 359 curr = java_lang_ClassLoader::parent(curr); 360 } 361 } 362 } 363 364 // It's a dependency we won't find through GC, add it. This is relatively rare 365 // Must handle over GC point. 366 Handle dependency(THREAD, to); 367 from_cld->_dependencies.add(dependency, CHECK); 368 } 369 370 371 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) { 372 // Check first if this dependency is already in the list. 373 // Save a pointer to the last to add to under the lock. 374 objArrayOop ok = _list_head; 375 objArrayOop last = NULL; 376 while (ok != NULL) { 377 last = ok; 378 if (ok->obj_at(0) == dependency()) { 379 // Don't need to add it 380 return; 381 } 382 ok = (objArrayOop)ok->obj_at(1); 383 } 384 385 // Must handle over GC points 386 assert (last != NULL, "dependencies should be initialized"); 387 objArrayHandle last_handle(THREAD, last); 388 389 // Create a new dependency node with fields for (class_loader or mirror, next) 390 objArrayOop deps = oopFactory::new_objectArray(2, CHECK); 391 deps->obj_at_put(0, dependency()); 392 393 // Must handle over GC points 394 objArrayHandle new_dependency(THREAD, deps); 395 396 // Add the dependency under lock 397 locked_add(last_handle, new_dependency, THREAD); 398 } 399 400 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle, 401 objArrayHandle new_dependency, 402 Thread* THREAD) { 403 404 // Have to lock and put the new dependency on the end of the dependency 405 // array so the card mark for CMS sees that this dependency is new. 406 // Can probably do this lock free with some effort. 407 ObjectLocker ol(Handle(THREAD, _list_head), THREAD); 408 409 oop loader_or_mirror = new_dependency->obj_at(0); 410 411 // Since the dependencies are only added, add to the end. 412 objArrayOop end = last_handle(); 413 objArrayOop last = NULL; 414 while (end != NULL) { 415 last = end; 416 // check again if another thread added it to the end. 417 if (end->obj_at(0) == loader_or_mirror) { 418 // Don't need to add it 419 return; 420 } 421 end = (objArrayOop)end->obj_at(1); 422 } 423 assert (last != NULL, "dependencies should be initialized"); 424 // fill in the first element with the oop in new_dependency. 425 if (last->obj_at(0) == NULL) { 426 last->obj_at_put(0, new_dependency->obj_at(0)); 427 } else { 428 last->obj_at_put(1, new_dependency()); 429 } 430 } 431 432 void ClassLoaderDataGraph::clear_claimed_marks() { 433 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 434 cld->clear_claimed(); 435 } 436 } 437 438 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) { 439 { 440 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 441 Klass* old_value = _klasses; 442 k->set_next_link(old_value); 443 // Link the new item into the list, making sure the linked class is stable 444 // since the list can be walked without a lock 445 OrderAccess::release_store_ptr(&_klasses, k); 446 } 447 448 if (publicize && k->class_loader_data() != NULL) { 449 ResourceMark rm; 450 log_trace(class, loader, data)("Adding k: " PTR_FORMAT " %s to CLD: " 451 PTR_FORMAT " loader: " PTR_FORMAT " %s", 452 p2i(k), 453 k->external_name(), 454 p2i(k->class_loader_data()), 455 p2i((void *)k->class_loader()), 456 loader_name()); 457 } 458 } 459 460 // Class iterator used by the compiler. It gets some number of classes at 461 // a safepoint to decay invocation counters on the methods. 462 class ClassLoaderDataGraphKlassIteratorStatic { 463 ClassLoaderData* _current_loader_data; 464 Klass* _current_class_entry; 465 public: 466 467 ClassLoaderDataGraphKlassIteratorStatic() : _current_loader_data(NULL), _current_class_entry(NULL) {} 468 469 InstanceKlass* try_get_next_class() { 470 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 471 int max_classes = InstanceKlass::number_of_instance_classes(); 472 assert(max_classes > 0, "should not be called with no instance classes"); 473 for (int i = 0; i < max_classes; ) { 474 475 if (_current_class_entry != NULL) { 476 Klass* k = _current_class_entry; 477 _current_class_entry = _current_class_entry->next_link(); 478 479 if (k->is_instance_klass()) { 480 InstanceKlass* ik = InstanceKlass::cast(k); 481 i++; // count all instance classes found 482 // Not yet loaded classes are counted in max_classes 483 // but only return loaded classes. 484 if (ik->is_loaded()) { 485 return ik; 486 } 487 } 488 } else { 489 // Go to next CLD 490 if (_current_loader_data != NULL) { 491 _current_loader_data = _current_loader_data->next(); 492 } 493 // Start at the beginning 494 if (_current_loader_data == NULL) { 495 _current_loader_data = ClassLoaderDataGraph::_head; 496 } 497 498 _current_class_entry = _current_loader_data->klasses(); 499 } 500 } 501 // Should never be reached unless all instance classes have failed or are not fully loaded. 502 // Caller handles NULL. 503 return NULL; 504 } 505 506 // If the current class for the static iterator is a class being unloaded or 507 // deallocated, adjust the current class. 508 void adjust_saved_class(ClassLoaderData* cld) { 509 if (_current_loader_data == cld) { 510 _current_loader_data = cld->next(); 511 if (_current_loader_data != NULL) { 512 _current_class_entry = _current_loader_data->klasses(); 513 } // else try_get_next_class will start at the head 514 } 515 } 516 517 void adjust_saved_class(Klass* klass) { 518 if (_current_class_entry == klass) { 519 _current_class_entry = klass->next_link(); 520 } 521 } 522 }; 523 524 static ClassLoaderDataGraphKlassIteratorStatic static_klass_iterator; 525 526 InstanceKlass* ClassLoaderDataGraph::try_get_next_class() { 527 return static_klass_iterator.try_get_next_class(); 528 } 529 530 531 // Remove a klass from the _klasses list for scratch_class during redefinition 532 // or parsed class in the case of an error. 533 void ClassLoaderData::remove_class(Klass* scratch_class) { 534 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 535 536 // Adjust global class iterator. 537 static_klass_iterator.adjust_saved_class(scratch_class); 538 539 Klass* prev = NULL; 540 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 541 if (k == scratch_class) { 542 if (prev == NULL) { 543 _klasses = k->next_link(); 544 } else { 545 Klass* next = k->next_link(); 546 prev->set_next_link(next); 547 } 548 return; 549 } 550 prev = k; 551 assert(k != k->next_link(), "no loops!"); 552 } 553 ShouldNotReachHere(); // should have found this class!! 554 } 555 556 void ClassLoaderData::unload() { 557 _unloading = true; 558 559 // Tell serviceability tools these classes are unloading 560 classes_do(InstanceKlass::notify_unload_class); 561 562 LogTarget(Debug, class, loader, data) lt; 563 if (lt.is_enabled()) { 564 ResourceMark rm; 565 LogStream ls(lt); 566 ls.print(": unload loader data " INTPTR_FORMAT, p2i(this)); 567 ls.print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()), 568 loader_name()); 569 if (is_anonymous()) { 570 ls.print(" for anonymous class " INTPTR_FORMAT " ", p2i(_klasses)); 571 } 572 ls.cr(); 573 } 574 575 // In some rare cases items added to this list will not be freed elsewhere. 576 // To keep it simple, just free everything in it here. 577 free_deallocate_list(); 578 579 // Clean up global class iterator for compiler 580 static_klass_iterator.adjust_saved_class(this); 581 } 582 583 ModuleEntryTable* ClassLoaderData::modules() { 584 // Lazily create the module entry table at first request. 585 // Lock-free access requires load_ptr_acquire. 586 ModuleEntryTable* modules = load_ptr_acquire(&_modules); 587 if (modules == NULL) { 588 MutexLocker m1(Module_lock); 589 // Check if _modules got allocated while we were waiting for this lock. 590 if ((modules = _modules) == NULL) { 591 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size); 592 593 { 594 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag); 595 // Ensure _modules is stable, since it is examined without a lock 596 OrderAccess::release_store_ptr(&_modules, modules); 597 } 598 } 599 } 600 return modules; 601 } 602 603 const int _boot_loader_dictionary_size = 1009; 604 const int _default_loader_dictionary_size = 107; 605 const int _prime_array_size = 8; // array of primes for system dictionary size 606 const int _average_depth_goal = 3; // goal for lookup length 607 const int _primelist[_prime_array_size] = {107, 1009, 2017, 4049, 5051, 10103, 20201, 40423}; 608 609 // Calculate a "good" dictionary size based 610 // on predicted or current loaded classes count. 611 static int calculate_dictionary_size(int classcount) { 612 int newsize = _primelist[0]; 613 if (classcount > 0 && !DumpSharedSpaces) { 614 int index = 0; 615 int desiredsize = classcount/_average_depth_goal; 616 for (newsize = _primelist[index]; index < _prime_array_size -1; 617 newsize = _primelist[++index]) { 618 if (desiredsize <= newsize) { 619 break; 620 } 621 } 622 } 623 return newsize; 624 } 625 626 Dictionary* ClassLoaderData::create_dictionary() { 627 assert(!is_anonymous(), "anonymous class loader data do not have a dictionary"); 628 int size; 629 if (_the_null_class_loader_data == NULL) { 630 size = _boot_loader_dictionary_size; 631 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) { 632 size = 1; // there's only one class in relection class loader and no initiated classes 633 } else if (is_system_class_loader_data()) { 634 size = calculate_dictionary_size(PredictedLoadedClassCount); 635 } else { 636 size = _default_loader_dictionary_size; 637 } 638 return new Dictionary(this, size); 639 } 640 641 // Unloading support 642 oop ClassLoaderData::keep_alive_object() const { 643 assert_locked_or_safepoint(_metaspace_lock); 644 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive"); 645 return is_anonymous() ? _klasses->java_mirror() : class_loader(); 646 } 647 648 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const { 649 bool alive = keep_alive() // null class loader and incomplete anonymous klasses. 650 || is_alive_closure->do_object_b(keep_alive_object()); 651 652 return alive; 653 } 654 655 ClassLoaderData::~ClassLoaderData() { 656 // Release C heap structures for all the classes. 657 classes_do(InstanceKlass::release_C_heap_structures); 658 659 // Release C heap allocated hashtable for all the packages. 660 if (_packages != NULL) { 661 // Destroy the table itself 662 delete _packages; 663 _packages = NULL; 664 } 665 666 // Release C heap allocated hashtable for all the modules. 667 if (_modules != NULL) { 668 // Destroy the table itself 669 delete _modules; 670 _modules = NULL; 671 } 672 673 // Release C heap allocated hashtable for the dictionary 674 if (_dictionary != NULL) { 675 // Destroy the table itself 676 delete _dictionary; 677 _dictionary = NULL; 678 } 679 680 if (_unnamed_module != NULL) { 681 _unnamed_module->delete_unnamed_module(); 682 _unnamed_module = NULL; 683 } 684 685 // release the metaspace 686 Metaspace *m = _metaspace; 687 if (m != NULL) { 688 _metaspace = NULL; 689 delete m; 690 } 691 // Clear all the JNI handles for methods 692 // These aren't deallocated and are going to look like a leak, but that's 693 // needed because we can't really get rid of jmethodIDs because we don't 694 // know when native code is going to stop using them. The spec says that 695 // they're "invalid" but existing programs likely rely on their being 696 // NULL after class unloading. 697 if (_jmethod_ids != NULL) { 698 Method::clear_jmethod_ids(this); 699 } 700 // Delete lock 701 delete _metaspace_lock; 702 703 // Delete free list 704 if (_deallocate_list != NULL) { 705 delete _deallocate_list; 706 } 707 } 708 709 // Returns true if this class loader data is for the system class loader. 710 bool ClassLoaderData::is_system_class_loader_data() const { 711 return SystemDictionary::is_system_class_loader(class_loader()); 712 } 713 714 // Returns true if this class loader data is for the platform class loader. 715 bool ClassLoaderData::is_platform_class_loader_data() const { 716 return SystemDictionary::is_platform_class_loader(class_loader()); 717 } 718 719 // Returns true if this class loader data is one of the 3 builtin 720 // (boot, application/system or platform) class loaders. Note, the 721 // builtin loaders are not freed by a GC. 722 bool ClassLoaderData::is_builtin_class_loader_data() const { 723 return (is_the_null_class_loader_data() || 724 SystemDictionary::is_system_class_loader(class_loader()) || 725 SystemDictionary::is_platform_class_loader(class_loader())); 726 } 727 728 Metaspace* ClassLoaderData::metaspace_non_null() { 729 // If the metaspace has not been allocated, create a new one. Might want 730 // to create smaller arena for Reflection class loaders also. 731 // The reason for the delayed allocation is because some class loaders are 732 // simply for delegating with no metadata of their own. 733 // Lock-free access requires load_ptr_acquire. 734 Metaspace* metaspace = load_ptr_acquire(&_metaspace); 735 if (metaspace == NULL) { 736 MutexLockerEx ml(_metaspace_lock, Mutex::_no_safepoint_check_flag); 737 // Check if _metaspace got allocated while we were waiting for this lock. 738 if ((metaspace = _metaspace) == NULL) { 739 if (this == the_null_class_loader_data()) { 740 assert (class_loader() == NULL, "Must be"); 741 metaspace = new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType); 742 } else if (is_anonymous()) { 743 if (class_loader() != NULL) { 744 log_trace(class, loader, data)("is_anonymous: %s", class_loader()->klass()->internal_name()); 745 } 746 metaspace = new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType); 747 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) { 748 if (class_loader() != NULL) { 749 log_trace(class, loader, data)("is_reflection: %s", class_loader()->klass()->internal_name()); 750 } 751 metaspace = new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType); 752 } else { 753 metaspace = new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType); 754 } 755 // Ensure _metaspace is stable, since it is examined without a lock 756 OrderAccess::release_store_ptr(&_metaspace, metaspace); 757 } 758 } 759 return metaspace; 760 } 761 762 OopHandle ClassLoaderData::add_handle(Handle h) { 763 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 764 return OopHandle(_handles.add(h())); 765 } 766 767 void ClassLoaderData::remove_handle_unsafe(OopHandle h) { 768 oop* obj = h.ptr(); 769 assert(_handles.contains(obj), "Got unexpected handle " PTR_FORMAT, p2i(obj)); 770 *(obj) = NULL; 771 } 772 773 // Add this metadata pointer to be freed when it's safe. This is only during 774 // class unloading because Handles might point to this metadata field. 775 void ClassLoaderData::add_to_deallocate_list(Metadata* m) { 776 // Metadata in shared region isn't deleted. 777 if (!m->is_shared()) { 778 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 779 if (_deallocate_list == NULL) { 780 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true); 781 } 782 _deallocate_list->append_if_missing(m); 783 } 784 } 785 786 // Deallocate free metadata on the free list. How useful the PermGen was! 787 void ClassLoaderData::free_deallocate_list() { 788 // Don't need lock, at safepoint 789 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 790 if (_deallocate_list == NULL) { 791 return; 792 } 793 // Go backwards because this removes entries that are freed. 794 for (int i = _deallocate_list->length() - 1; i >= 0; i--) { 795 Metadata* m = _deallocate_list->at(i); 796 if (!m->on_stack()) { 797 _deallocate_list->remove_at(i); 798 // There are only three types of metadata that we deallocate directly. 799 // Cast them so they can be used by the template function. 800 if (m->is_method()) { 801 MetadataFactory::free_metadata(this, (Method*)m); 802 } else if (m->is_constantPool()) { 803 MetadataFactory::free_metadata(this, (ConstantPool*)m); 804 } else if (m->is_klass()) { 805 MetadataFactory::free_metadata(this, (InstanceKlass*)m); 806 } else { 807 ShouldNotReachHere(); 808 } 809 } else { 810 // Metadata is alive. 811 // If scratch_class is on stack then it shouldn't be on this list! 812 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(), 813 "scratch classes on this list should be dead"); 814 // Also should assert that other metadata on the list was found in handles. 815 } 816 } 817 } 818 819 // These anonymous class loaders are to contain classes used for JSR292 820 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) { 821 // Add a new class loader data to the graph. 822 Handle lh(THREAD, loader); 823 return ClassLoaderDataGraph::add(lh, true, THREAD); 824 } 825 826 const char* ClassLoaderData::loader_name() { 827 // Handles null class loader 828 return SystemDictionary::loader_name(class_loader()); 829 } 830 831 #ifndef PRODUCT 832 // Define to dump klasses 833 #undef CLD_DUMP_KLASSES 834 835 void ClassLoaderData::dump(outputStream * const out) { 836 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: " PTR_FORMAT " %s {", 837 p2i(this), p2i((void *)class_loader()), 838 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name()); 839 if (claimed()) out->print(" claimed "); 840 if (is_unloading()) out->print(" unloading "); 841 out->cr(); 842 if (metaspace_or_null() != NULL) { 843 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null())); 844 metaspace_or_null()->dump(out); 845 } else { 846 out->print_cr("metaspace: NULL"); 847 } 848 849 #ifdef CLD_DUMP_KLASSES 850 if (Verbose) { 851 Klass* k = _klasses; 852 while (k != NULL) { 853 out->print_cr("klass " PTR_FORMAT ", %s, CT: %d, MUT: %d", k, k->name()->as_C_string(), 854 k->has_modified_oops(), k->has_accumulated_modified_oops()); 855 assert(k != k->next_link(), "no loops!"); 856 k = k->next_link(); 857 } 858 } 859 #endif // CLD_DUMP_KLASSES 860 #undef CLD_DUMP_KLASSES 861 if (_jmethod_ids != NULL) { 862 Method::print_jmethod_ids(this, out); 863 } 864 out->print_cr("}"); 865 } 866 #endif // PRODUCT 867 868 void ClassLoaderData::verify() { 869 assert_locked_or_safepoint(_metaspace_lock); 870 oop cl = class_loader(); 871 872 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same"); 873 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be"); 874 875 // Verify the integrity of the allocated space. 876 if (metaspace_or_null() != NULL) { 877 metaspace_or_null()->verify(); 878 } 879 880 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 881 guarantee(k->class_loader_data() == this, "Must be the same"); 882 k->verify(); 883 assert(k != k->next_link(), "no loops!"); 884 } 885 } 886 887 bool ClassLoaderData::contains_klass(Klass* klass) { 888 // Lock-free access requires load_ptr_acquire 889 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) { 890 if (k == klass) return true; 891 } 892 return false; 893 } 894 895 896 // GC root of class loader data created. 897 ClassLoaderData* ClassLoaderDataGraph::_head = NULL; 898 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL; 899 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL; 900 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL; 901 902 bool ClassLoaderDataGraph::_should_purge = false; 903 bool ClassLoaderDataGraph::_metaspace_oom = false; 904 905 // Add a new class loader data node to the list. Assign the newly created 906 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field 907 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) { 908 // We need to allocate all the oops for the ClassLoaderData before allocating the 909 // actual ClassLoaderData object. 910 ClassLoaderData::Dependencies dependencies(CHECK_NULL); 911 912 NoSafepointVerifier no_safepoints; // we mustn't GC until we've installed the 913 // ClassLoaderData in the graph since the CLD 914 // contains unhandled oops 915 916 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies); 917 918 919 if (!is_anonymous) { 920 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader()); 921 // First, Atomically set it 922 ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL); 923 if (old != NULL) { 924 delete cld; 925 // Returns the data. 926 return old; 927 } 928 } 929 930 // We won the race, and therefore the task of adding the data to the list of 931 // class loader data 932 ClassLoaderData** list_head = &_head; 933 ClassLoaderData* next = _head; 934 935 do { 936 cld->set_next(next); 937 ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next); 938 if (exchanged == next) { 939 LogTarget(Debug, class, loader, data) lt; 940 if (lt.is_enabled()) { 941 PauseNoSafepointVerifier pnsv(&no_safepoints); // Need safe points for JavaCalls::call_virtual 942 LogStream ls(lt); 943 print_creation(&ls, loader, cld, CHECK_NULL); 944 } 945 return cld; 946 } 947 next = exchanged; 948 } while (true); 949 } 950 951 void ClassLoaderDataGraph::print_creation(outputStream* out, Handle loader, ClassLoaderData* cld, TRAPS) { 952 Handle string; 953 if (loader.not_null()) { 954 // Include the result of loader.toString() in the output. This allows 955 // the user of the log to identify the class loader instance. 956 JavaValue result(T_OBJECT); 957 Klass* spec_klass = SystemDictionary::ClassLoader_klass(); 958 JavaCalls::call_virtual(&result, 959 loader, 960 spec_klass, 961 vmSymbols::toString_name(), 962 vmSymbols::void_string_signature(), 963 CHECK); 964 assert(result.get_type() == T_OBJECT, "just checking"); 965 string = Handle(THREAD, (oop)result.get_jobject()); 966 } 967 968 ResourceMark rm; 969 out->print("create class loader data " INTPTR_FORMAT, p2i(cld)); 970 out->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()), 971 cld->loader_name()); 972 973 if (string.not_null()) { 974 out->print(": "); 975 java_lang_String::print(string(), out); 976 } 977 out->cr(); 978 } 979 980 981 void ClassLoaderDataGraph::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 982 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 983 cld->oops_do(f, klass_closure, must_claim); 984 } 985 } 986 987 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 988 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 989 if (cld->keep_alive()) { 990 cld->oops_do(f, klass_closure, must_claim); 991 } 992 } 993 } 994 995 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 996 if (ClassUnloading) { 997 keep_alive_oops_do(f, klass_closure, must_claim); 998 } else { 999 oops_do(f, klass_closure, must_claim); 1000 } 1001 } 1002 1003 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) { 1004 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) { 1005 cl->do_cld(cld); 1006 } 1007 } 1008 1009 void ClassLoaderDataGraph::cld_unloading_do(CLDClosure* cl) { 1010 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 1011 // Only walk the head until any clds not purged from prior unloading 1012 // (CMS doesn't purge right away). 1013 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) { 1014 assert(cld->is_unloading(), "invariant"); 1015 cl->do_cld(cld); 1016 } 1017 } 1018 1019 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) { 1020 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) { 1021 CLDClosure* closure = cld->keep_alive() ? strong : weak; 1022 if (closure != NULL) { 1023 closure->do_cld(cld); 1024 } 1025 } 1026 } 1027 1028 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) { 1029 roots_cld_do(cl, NULL); 1030 } 1031 1032 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) { 1033 if (ClassUnloading) { 1034 keep_alive_cld_do(cl); 1035 } else { 1036 cld_do(cl); 1037 } 1038 } 1039 1040 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) { 1041 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 1042 cld->classes_do(klass_closure); 1043 } 1044 } 1045 1046 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) { 1047 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 1048 cld->classes_do(f); 1049 } 1050 } 1051 1052 void ClassLoaderDataGraph::methods_do(void f(Method*)) { 1053 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 1054 cld->methods_do(f); 1055 } 1056 } 1057 1058 void ClassLoaderDataGraph::modules_do(void f(ModuleEntry*)) { 1059 assert_locked_or_safepoint(Module_lock); 1060 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 1061 cld->modules_do(f); 1062 } 1063 } 1064 1065 void ClassLoaderDataGraph::modules_unloading_do(void f(ModuleEntry*)) { 1066 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 1067 // Only walk the head until any clds not purged from prior unloading 1068 // (CMS doesn't purge right away). 1069 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) { 1070 assert(cld->is_unloading(), "invariant"); 1071 cld->modules_do(f); 1072 } 1073 } 1074 1075 void ClassLoaderDataGraph::packages_do(void f(PackageEntry*)) { 1076 assert_locked_or_safepoint(Module_lock); 1077 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 1078 cld->packages_do(f); 1079 } 1080 } 1081 1082 void ClassLoaderDataGraph::packages_unloading_do(void f(PackageEntry*)) { 1083 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 1084 // Only walk the head until any clds not purged from prior unloading 1085 // (CMS doesn't purge right away). 1086 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) { 1087 assert(cld->is_unloading(), "invariant"); 1088 cld->packages_do(f); 1089 } 1090 } 1091 1092 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) { 1093 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 1094 cld->loaded_classes_do(klass_closure); 1095 } 1096 } 1097 1098 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) { 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->classes_do(f); 1105 } 1106 } 1107 1108 #define FOR_ALL_DICTIONARY(X) for (ClassLoaderData* X = _head; X != NULL; X = X->next()) \ 1109 if (X->dictionary() != NULL) 1110 1111 // Walk classes in the loaded class dictionaries in various forms. 1112 // Only walks the classes defined in this class loader. 1113 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*)) { 1114 FOR_ALL_DICTIONARY(cld) { 1115 cld->dictionary()->classes_do(f); 1116 } 1117 } 1118 1119 // Only walks the classes defined in this class loader. 1120 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*, TRAPS), TRAPS) { 1121 FOR_ALL_DICTIONARY(cld) { 1122 cld->dictionary()->classes_do(f, CHECK); 1123 } 1124 } 1125 1126 // Walks all entries in the dictionary including entries initiated by this class loader. 1127 void ClassLoaderDataGraph::dictionary_all_entries_do(void f(InstanceKlass*, ClassLoaderData*)) { 1128 FOR_ALL_DICTIONARY(cld) { 1129 cld->dictionary()->all_entries_do(f); 1130 } 1131 } 1132 1133 void ClassLoaderDataGraph::verify_dictionary() { 1134 FOR_ALL_DICTIONARY(cld) { 1135 cld->dictionary()->verify(); 1136 } 1137 } 1138 1139 void ClassLoaderDataGraph::print_dictionary(outputStream* st) { 1140 FOR_ALL_DICTIONARY(cld) { 1141 st->print("Dictionary for "); 1142 cld->print_value_on(st); 1143 st->cr(); 1144 cld->dictionary()->print_on(st); 1145 st->cr(); 1146 } 1147 } 1148 1149 void ClassLoaderDataGraph::print_dictionary_statistics(outputStream* st) { 1150 FOR_ALL_DICTIONARY(cld) { 1151 ResourceMark rm; 1152 stringStream tempst; 1153 tempst.print("System Dictionary for %s", cld->loader_name()); 1154 cld->dictionary()->print_table_statistics(st, tempst.as_string()); 1155 } 1156 } 1157 1158 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() { 1159 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?"); 1160 1161 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>(); 1162 1163 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true); 1164 ClassLoaderData* curr = _head; 1165 while (curr != _saved_head) { 1166 if (!curr->claimed()) { 1167 array->push(curr); 1168 LogTarget(Debug, class, loader, data) lt; 1169 if (lt.is_enabled()) { 1170 LogStream ls(lt); 1171 ls.print("found new CLD: "); 1172 curr->print_value_on(&ls); 1173 ls.cr(); 1174 } 1175 } 1176 1177 curr = curr->_next; 1178 } 1179 1180 return array; 1181 } 1182 1183 bool ClassLoaderDataGraph::unload_list_contains(const void* x) { 1184 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint"); 1185 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) { 1186 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) { 1187 return true; 1188 } 1189 } 1190 return false; 1191 } 1192 1193 #ifndef PRODUCT 1194 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) { 1195 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 1196 if (loader_data == data) { 1197 return true; 1198 } 1199 } 1200 1201 return false; 1202 } 1203 #endif // PRODUCT 1204 1205 1206 // Move class loader data from main list to the unloaded list for unloading 1207 // and deallocation later. 1208 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure, 1209 bool clean_previous_versions) { 1210 1211 ClassLoaderData* data = _head; 1212 ClassLoaderData* prev = NULL; 1213 bool seen_dead_loader = false; 1214 1215 // Mark metadata seen on the stack only so we can delete unneeded entries. 1216 // Only walk all metadata, including the expensive code cache walk, for Full GC 1217 // and only if class redefinition and if there's previous versions of 1218 // Klasses to delete. 1219 bool walk_all_metadata = clean_previous_versions && 1220 JvmtiExport::has_redefined_a_class() && 1221 InstanceKlass::has_previous_versions_and_reset(); 1222 MetadataOnStackMark md_on_stack(walk_all_metadata); 1223 1224 // Save previous _unloading pointer for CMS which may add to unloading list before 1225 // purging and we don't want to rewalk the previously unloaded class loader data. 1226 _saved_unloading = _unloading; 1227 1228 data = _head; 1229 while (data != NULL) { 1230 if (data->is_alive(is_alive_closure)) { 1231 // clean metaspace 1232 if (walk_all_metadata) { 1233 data->classes_do(InstanceKlass::purge_previous_versions); 1234 } 1235 data->free_deallocate_list(); 1236 prev = data; 1237 data = data->next(); 1238 continue; 1239 } 1240 seen_dead_loader = true; 1241 ClassLoaderData* dead = data; 1242 dead->unload(); 1243 data = data->next(); 1244 // Remove from loader list. 1245 // This class loader data will no longer be found 1246 // in the ClassLoaderDataGraph. 1247 if (prev != NULL) { 1248 prev->set_next(data); 1249 } else { 1250 assert(dead == _head, "sanity check"); 1251 _head = data; 1252 } 1253 dead->set_next(_unloading); 1254 _unloading = dead; 1255 } 1256 1257 if (seen_dead_loader) { 1258 data = _head; 1259 while (data != NULL) { 1260 // Remove entries in the dictionary of live class loader that have 1261 // initiated loading classes in a dead class loader. 1262 if (data->dictionary() != NULL) { 1263 data->dictionary()->do_unloading(); 1264 } 1265 // Walk a ModuleEntry's reads, and a PackageEntry's exports 1266 // lists to determine if there are modules on those lists that are now 1267 // dead and should be removed. A module's life cycle is equivalent 1268 // to its defining class loader's life cycle. Since a module is 1269 // considered dead if its class loader is dead, these walks must 1270 // occur after each class loader's aliveness is determined. 1271 if (data->packages() != NULL) { 1272 data->packages()->purge_all_package_exports(); 1273 } 1274 if (data->modules_defined()) { 1275 data->modules()->purge_all_module_reads(); 1276 } 1277 data = data->next(); 1278 } 1279 1280 post_class_unload_events(); 1281 } 1282 1283 return seen_dead_loader; 1284 } 1285 1286 void ClassLoaderDataGraph::purge() { 1287 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 1288 ClassLoaderData* list = _unloading; 1289 _unloading = NULL; 1290 ClassLoaderData* next = list; 1291 bool classes_unloaded = false; 1292 while (next != NULL) { 1293 ClassLoaderData* purge_me = next; 1294 next = purge_me->next(); 1295 delete purge_me; 1296 classes_unloaded = true; 1297 } 1298 if (classes_unloaded) { 1299 Metaspace::purge(); 1300 set_metaspace_oom(false); 1301 } 1302 } 1303 1304 void ClassLoaderDataGraph::post_class_unload_events() { 1305 #if INCLUDE_TRACE 1306 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 1307 if (Tracing::enabled()) { 1308 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) { 1309 assert(_unloading != NULL, "need class loader data unload list!"); 1310 _class_unload_time = Ticks::now(); 1311 classes_unloading_do(&class_unload_event); 1312 } 1313 Tracing::on_unloading_classes(); 1314 } 1315 #endif 1316 } 1317 1318 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic() 1319 : _next_klass(NULL) { 1320 ClassLoaderData* cld = ClassLoaderDataGraph::_head; 1321 Klass* klass = NULL; 1322 1323 // Find the first klass in the CLDG. 1324 while (cld != NULL) { 1325 assert_locked_or_safepoint(cld->metaspace_lock()); 1326 klass = cld->_klasses; 1327 if (klass != NULL) { 1328 _next_klass = klass; 1329 return; 1330 } 1331 cld = cld->next(); 1332 } 1333 } 1334 1335 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) { 1336 Klass* next = klass->next_link(); 1337 if (next != NULL) { 1338 return next; 1339 } 1340 1341 // No more klasses in the current CLD. Time to find a new CLD. 1342 ClassLoaderData* cld = klass->class_loader_data(); 1343 assert_locked_or_safepoint(cld->metaspace_lock()); 1344 while (next == NULL) { 1345 cld = cld->next(); 1346 if (cld == NULL) { 1347 break; 1348 } 1349 next = cld->_klasses; 1350 } 1351 1352 return next; 1353 } 1354 1355 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() { 1356 Klass* head = _next_klass; 1357 1358 while (head != NULL) { 1359 Klass* next = next_klass_in_cldg(head); 1360 1361 Klass* old_head = (Klass*)Atomic::cmpxchg_ptr(next, &_next_klass, head); 1362 1363 if (old_head == head) { 1364 return head; // Won the CAS. 1365 } 1366 1367 head = old_head; 1368 } 1369 1370 // Nothing more for the iterator to hand out. 1371 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head)); 1372 return NULL; 1373 } 1374 1375 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() { 1376 _data = ClassLoaderDataGraph::_head; 1377 } 1378 1379 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {} 1380 1381 #ifndef PRODUCT 1382 // callable from debugger 1383 extern "C" int print_loader_data_graph() { 1384 ClassLoaderDataGraph::dump_on(tty); 1385 return 0; 1386 } 1387 1388 void ClassLoaderDataGraph::verify() { 1389 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 1390 data->verify(); 1391 } 1392 } 1393 1394 void ClassLoaderDataGraph::dump_on(outputStream * const out) { 1395 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 1396 data->dump(out); 1397 } 1398 MetaspaceAux::dump(out); 1399 } 1400 #endif // PRODUCT 1401 1402 void ClassLoaderData::print_value_on(outputStream* out) const { 1403 if (class_loader() == NULL) { 1404 out->print("NULL class loader"); 1405 } else { 1406 out->print("class loader " INTPTR_FORMAT " ", p2i(this)); 1407 class_loader()->print_value_on(out); 1408 } 1409 } 1410 1411 void ClassLoaderData::print_on(outputStream* out) const { 1412 if (class_loader() == NULL) { 1413 out->print("NULL class loader"); 1414 } else { 1415 out->print("class loader " INTPTR_FORMAT " ", p2i(this)); 1416 class_loader()->print_on(out); 1417 } 1418 } 1419 1420 #if INCLUDE_TRACE 1421 1422 Ticks ClassLoaderDataGraph::_class_unload_time; 1423 1424 void ClassLoaderDataGraph::class_unload_event(Klass* const k) { 1425 assert(k != NULL, "invariant"); 1426 1427 // post class unload event 1428 EventClassUnload event(UNTIMED); 1429 event.set_endtime(_class_unload_time); 1430 event.set_unloadedClass(k); 1431 event.set_definingClassLoader(k->class_loader_data()); 1432 event.commit(); 1433 } 1434 1435 #endif // INCLUDE_TRACE