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/symbolTable.hpp" 58 #include "classfile/systemDictionary.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/resourceArea.hpp" 65 #include "memory/universe.hpp" 66 #include "oops/access.inline.hpp" 67 #include "oops/oop.inline.hpp" 68 #include "oops/oopHandle.inline.hpp" 69 #include "oops/weakHandle.inline.hpp" 70 #include "runtime/atomic.hpp" 71 #include "runtime/handles.inline.hpp" 72 #include "runtime/mutex.hpp" 73 #include "runtime/orderAccess.hpp" 74 #include "runtime/safepoint.hpp" 75 #include "runtime/safepointVerifiers.hpp" 76 #include "utilities/growableArray.hpp" 77 #include "utilities/macros.hpp" 78 #include "utilities/ostream.hpp" 79 #include "utilities/ticks.hpp" 80 #if INCLUDE_JFR 81 #include "jfr/jfr.hpp" 82 #include "jfr/jfrEvents.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 // Obtain and set the class loader's name within the ClassLoaderData so 109 // it will be available for error messages, logging, JFR, etc. The name 110 // and klass are available after the class_loader oop is no longer alive, 111 // during unloading. 112 void ClassLoaderData::initialize_name(Handle class_loader) { 113 Thread* THREAD = Thread::current(); 114 ResourceMark rm(THREAD); 115 116 // Obtain the class loader's name. If the class loader's name was not 117 // explicitly set during construction, the CLD's _name field will be null. 118 oop cl_name = java_lang_ClassLoader::name(class_loader()); 119 if (cl_name != NULL) { 120 const char* cl_instance_name = java_lang_String::as_utf8_string(cl_name); 121 122 if (cl_instance_name != NULL && cl_instance_name[0] != '\0') { 123 // Can't throw InternalError and SymbolTable doesn't throw OOM anymore. 124 _name = SymbolTable::new_symbol(cl_instance_name, CATCH); 125 } 126 } 127 128 // Obtain the class loader's name and identity hash. If the class loader's 129 // name was not explicitly set during construction, the class loader's name and id 130 // will be set to the qualified class name of the class loader along with its 131 // identity hash. 132 // If for some reason the ClassLoader's constructor has not been run, instead of 133 // leaving the _name_and_id field null, fall back to the external qualified class 134 // name. Thus CLD's _name_and_id field should never have a null value. 135 oop cl_name_and_id = java_lang_ClassLoader::nameAndId(class_loader()); 136 const char* cl_instance_name_and_id = 137 (cl_name_and_id == NULL) ? _class_loader_klass->external_name() : 138 java_lang_String::as_utf8_string(cl_name_and_id); 139 assert(cl_instance_name_and_id != NULL && cl_instance_name_and_id[0] != '\0', "class loader has no name and id"); 140 // Can't throw InternalError and SymbolTable doesn't throw OOM anymore. 141 _name_and_id = SymbolTable::new_symbol(cl_instance_name_and_id, CATCH); 142 } 143 144 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous) : 145 _is_anonymous(is_anonymous), 146 // An anonymous class loader data doesn't have anything to keep 147 // it from being unloaded during parsing of the anonymous class. 148 // The null-class-loader should always be kept alive. 149 _keep_alive((is_anonymous || h_class_loader.is_null()) ? 1 : 0), 150 _metaspace(NULL), _unloading(false), _klasses(NULL), 151 _modules(NULL), _packages(NULL), _unnamed_module(NULL), _dictionary(NULL), 152 _claimed(0), _modified_oops(true), _accumulated_modified_oops(false), 153 _jmethod_ids(NULL), _handles(), _deallocate_list(NULL), 154 _next(NULL), 155 _class_loader_klass(NULL), _name(NULL), _name_and_id(NULL), 156 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true, 157 Monitor::_safepoint_check_never)) { 158 159 if (!h_class_loader.is_null()) { 160 _class_loader = _handles.add(h_class_loader()); 161 _class_loader_klass = h_class_loader->klass(); 162 } 163 164 if (!is_anonymous) { 165 // The holder is initialized later for anonymous classes, and before calling anything 166 // that call class_loader(). 167 initialize_holder(h_class_loader); 168 169 // A ClassLoaderData created solely for an anonymous class should never have a 170 // ModuleEntryTable or PackageEntryTable created for it. The defining package 171 // and module for an anonymous class will be found in its host class. 172 _packages = new PackageEntryTable(PackageEntryTable::_packagetable_entry_size); 173 if (h_class_loader.is_null()) { 174 // Create unnamed module for boot loader 175 _unnamed_module = ModuleEntry::create_boot_unnamed_module(this); 176 } else { 177 // Create unnamed module for all other loaders 178 _unnamed_module = ModuleEntry::create_unnamed_module(this); 179 } 180 _dictionary = create_dictionary(); 181 } 182 183 NOT_PRODUCT(_dependency_count = 0); // number of class loader dependencies 184 185 JFR_ONLY(INIT_ID(this);) 186 } 187 188 ClassLoaderData::ChunkedHandleList::~ChunkedHandleList() { 189 Chunk* c = _head; 190 while (c != NULL) { 191 Chunk* next = c->_next; 192 delete c; 193 c = next; 194 } 195 } 196 197 oop* ClassLoaderData::ChunkedHandleList::add(oop o) { 198 if (_head == NULL || _head->_size == Chunk::CAPACITY) { 199 Chunk* next = new Chunk(_head); 200 OrderAccess::release_store(&_head, next); 201 } 202 oop* handle = &_head->_data[_head->_size]; 203 *handle = o; 204 OrderAccess::release_store(&_head->_size, _head->_size + 1); 205 return handle; 206 } 207 208 int ClassLoaderData::ChunkedHandleList::count() const { 209 int count = 0; 210 Chunk* chunk = _head; 211 while (chunk != NULL) { 212 count += chunk->_size; 213 chunk = chunk->_next; 214 } 215 return count; 216 } 217 218 inline void ClassLoaderData::ChunkedHandleList::oops_do_chunk(OopClosure* f, Chunk* c, const juint size) { 219 for (juint i = 0; i < size; i++) { 220 if (c->_data[i] != NULL) { 221 f->do_oop(&c->_data[i]); 222 } 223 } 224 } 225 226 void ClassLoaderData::ChunkedHandleList::oops_do(OopClosure* f) { 227 Chunk* head = OrderAccess::load_acquire(&_head); 228 if (head != NULL) { 229 // Must be careful when reading size of head 230 oops_do_chunk(f, head, OrderAccess::load_acquire(&head->_size)); 231 for (Chunk* c = head->_next; c != NULL; c = c->_next) { 232 oops_do_chunk(f, c, c->_size); 233 } 234 } 235 } 236 237 class VerifyContainsOopClosure : public OopClosure { 238 oop _target; 239 bool _found; 240 241 public: 242 VerifyContainsOopClosure(oop target) : _target(target), _found(false) {} 243 244 void do_oop(oop* p) { 245 if (p != NULL && oopDesc::equals(RawAccess<>::oop_load(p), _target)) { 246 _found = true; 247 } 248 } 249 250 void do_oop(narrowOop* p) { 251 // The ChunkedHandleList should not contain any narrowOop 252 ShouldNotReachHere(); 253 } 254 255 bool found() const { 256 return _found; 257 } 258 }; 259 260 bool ClassLoaderData::ChunkedHandleList::contains(oop p) { 261 VerifyContainsOopClosure cl(p); 262 oops_do(&cl); 263 return cl.found(); 264 } 265 266 #ifndef PRODUCT 267 bool ClassLoaderData::ChunkedHandleList::owner_of(oop* oop_handle) { 268 Chunk* chunk = _head; 269 while (chunk != NULL) { 270 if (&(chunk->_data[0]) <= oop_handle && oop_handle < &(chunk->_data[chunk->_size])) { 271 return true; 272 } 273 chunk = chunk->_next; 274 } 275 return false; 276 } 277 #endif // PRODUCT 278 279 bool ClassLoaderData::claim() { 280 if (_claimed == 1) { 281 return false; 282 } 283 284 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0; 285 } 286 287 // Anonymous classes have their own ClassLoaderData that is marked to keep alive 288 // while the class is being parsed, and if the class appears on the module fixup list. 289 // Due to the uniqueness that no other class shares the anonymous class' name or 290 // ClassLoaderData, no other non-GC thread has knowledge of the anonymous class while 291 // it is being defined, therefore _keep_alive is not volatile or atomic. 292 void ClassLoaderData::inc_keep_alive() { 293 if (is_anonymous()) { 294 assert(_keep_alive >= 0, "Invalid keep alive increment count"); 295 _keep_alive++; 296 } 297 } 298 299 void ClassLoaderData::dec_keep_alive() { 300 if (is_anonymous()) { 301 assert(_keep_alive > 0, "Invalid keep alive decrement count"); 302 _keep_alive--; 303 } 304 } 305 306 void ClassLoaderData::oops_do(OopClosure* f, bool must_claim, bool clear_mod_oops) { 307 if (must_claim && !claim()) { 308 return; 309 } 310 311 // Only clear modified_oops after the ClassLoaderData is claimed. 312 if (clear_mod_oops) { 313 clear_modified_oops(); 314 } 315 316 _handles.oops_do(f); 317 } 318 319 void ClassLoaderData::classes_do(KlassClosure* klass_closure) { 320 // Lock-free access requires load_acquire 321 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 322 klass_closure->do_klass(k); 323 assert(k != k->next_link(), "no loops!"); 324 } 325 } 326 327 void ClassLoaderData::classes_do(void f(Klass * const)) { 328 // Lock-free access requires load_acquire 329 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 330 f(k); 331 assert(k != k->next_link(), "no loops!"); 332 } 333 } 334 335 void ClassLoaderData::methods_do(void f(Method*)) { 336 // Lock-free access requires load_acquire 337 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 338 if (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded()) { 339 InstanceKlass::cast(k)->methods_do(f); 340 } 341 } 342 } 343 344 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) { 345 // Lock-free access requires load_acquire 346 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 347 // Do not filter ArrayKlass oops here... 348 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) { 349 klass_closure->do_klass(k); 350 } 351 } 352 } 353 354 void ClassLoaderData::classes_do(void f(InstanceKlass*)) { 355 // Lock-free access requires load_acquire 356 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 357 if (k->is_instance_klass()) { 358 f(InstanceKlass::cast(k)); 359 } 360 assert(k != k->next_link(), "no loops!"); 361 } 362 } 363 364 void ClassLoaderData::modules_do(void f(ModuleEntry*)) { 365 assert_locked_or_safepoint(Module_lock); 366 if (_unnamed_module != NULL) { 367 f(_unnamed_module); 368 } 369 if (_modules != NULL) { 370 for (int i = 0; i < _modules->table_size(); i++) { 371 for (ModuleEntry* entry = _modules->bucket(i); 372 entry != NULL; 373 entry = entry->next()) { 374 f(entry); 375 } 376 } 377 } 378 } 379 380 void ClassLoaderData::packages_do(void f(PackageEntry*)) { 381 assert_locked_or_safepoint(Module_lock); 382 if (_packages != NULL) { 383 for (int i = 0; i < _packages->table_size(); i++) { 384 for (PackageEntry* entry = _packages->bucket(i); 385 entry != NULL; 386 entry = entry->next()) { 387 f(entry); 388 } 389 } 390 } 391 } 392 393 void ClassLoaderData::record_dependency(const Klass* k) { 394 assert(k != NULL, "invariant"); 395 396 ClassLoaderData * const from_cld = this; 397 ClassLoaderData * const to_cld = k->class_loader_data(); 398 399 // Do not need to record dependency if the dependency is to a class whose 400 // class loader data is never freed. (i.e. the dependency's class loader 401 // is one of the three builtin class loaders and the dependency is not 402 // anonymous.) 403 if (to_cld->is_permanent_class_loader_data()) { 404 return; 405 } 406 407 oop to; 408 if (to_cld->is_anonymous()) { 409 // Just return if an anonymous class is attempting to record a dependency 410 // to itself. (Note that every anonymous class has its own unique class 411 // loader data.) 412 if (to_cld == from_cld) { 413 return; 414 } 415 // Anonymous class dependencies are through the mirror. 416 to = k->java_mirror(); 417 } else { 418 to = to_cld->class_loader(); 419 oop from = from_cld->class_loader(); 420 421 // Just return if this dependency is to a class with the same or a parent 422 // class_loader. 423 if (oopDesc::equals(from, to) || java_lang_ClassLoader::isAncestor(from, to)) { 424 return; // this class loader is in the parent list, no need to add it. 425 } 426 } 427 428 // It's a dependency we won't find through GC, add it. 429 if (!_handles.contains(to)) { 430 NOT_PRODUCT(Atomic::inc(&_dependency_count)); 431 LogTarget(Trace, class, loader, data) lt; 432 if (lt.is_enabled()) { 433 ResourceMark rm; 434 LogStream ls(lt); 435 ls.print("adding dependency from "); 436 print_value_on(&ls); 437 ls.print(" to "); 438 to_cld->print_value_on(&ls); 439 ls.cr(); 440 } 441 Handle dependency(Thread::current(), to); 442 add_handle(dependency); 443 // Added a potentially young gen oop to the ClassLoaderData 444 record_modified_oops(); 445 } 446 } 447 448 449 void ClassLoaderDataGraph::clear_claimed_marks() { 450 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 451 cld->clear_claimed(); 452 } 453 } 454 455 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) { 456 { 457 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 458 Klass* old_value = _klasses; 459 k->set_next_link(old_value); 460 // Link the new item into the list, making sure the linked class is stable 461 // since the list can be walked without a lock 462 OrderAccess::release_store(&_klasses, k); 463 if (k->is_array_klass()) { 464 ClassLoaderDataGraph::inc_array_classes(1); 465 } else { 466 ClassLoaderDataGraph::inc_instance_classes(1); 467 } 468 } 469 470 if (publicize) { 471 LogTarget(Trace, class, loader, data) lt; 472 if (lt.is_enabled()) { 473 ResourceMark rm; 474 LogStream ls(lt); 475 ls.print("Adding k: " PTR_FORMAT " %s to ", p2i(k), k->external_name()); 476 print_value_on(&ls); 477 ls.cr(); 478 } 479 } 480 } 481 482 // Class iterator used by the compiler. It gets some number of classes at 483 // a safepoint to decay invocation counters on the methods. 484 class ClassLoaderDataGraphKlassIteratorStatic { 485 ClassLoaderData* _current_loader_data; 486 Klass* _current_class_entry; 487 public: 488 489 ClassLoaderDataGraphKlassIteratorStatic() : _current_loader_data(NULL), _current_class_entry(NULL) {} 490 491 InstanceKlass* try_get_next_class() { 492 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 493 size_t max_classes = ClassLoaderDataGraph::num_instance_classes(); 494 assert(max_classes > 0, "should not be called with no instance classes"); 495 for (size_t i = 0; i < max_classes; ) { 496 497 if (_current_class_entry != NULL) { 498 Klass* k = _current_class_entry; 499 _current_class_entry = _current_class_entry->next_link(); 500 501 if (k->is_instance_klass()) { 502 InstanceKlass* ik = InstanceKlass::cast(k); 503 i++; // count all instance classes found 504 // Not yet loaded classes are counted in max_classes 505 // but only return loaded classes. 506 if (ik->is_loaded()) { 507 return ik; 508 } 509 } 510 } else { 511 // Go to next CLD 512 if (_current_loader_data != NULL) { 513 _current_loader_data = _current_loader_data->next(); 514 } 515 // Start at the beginning 516 if (_current_loader_data == NULL) { 517 _current_loader_data = ClassLoaderDataGraph::_head; 518 } 519 520 _current_class_entry = _current_loader_data->klasses(); 521 } 522 } 523 // Should never be reached unless all instance classes have failed or are not fully loaded. 524 // Caller handles NULL. 525 return NULL; 526 } 527 528 // If the current class for the static iterator is a class being unloaded or 529 // deallocated, adjust the current class. 530 void adjust_saved_class(ClassLoaderData* cld) { 531 if (_current_loader_data == cld) { 532 _current_loader_data = cld->next(); 533 if (_current_loader_data != NULL) { 534 _current_class_entry = _current_loader_data->klasses(); 535 } // else try_get_next_class will start at the head 536 } 537 } 538 539 void adjust_saved_class(Klass* klass) { 540 if (_current_class_entry == klass) { 541 _current_class_entry = klass->next_link(); 542 } 543 } 544 }; 545 546 static ClassLoaderDataGraphKlassIteratorStatic static_klass_iterator; 547 548 InstanceKlass* ClassLoaderDataGraph::try_get_next_class() { 549 return static_klass_iterator.try_get_next_class(); 550 } 551 552 553 void ClassLoaderData::initialize_holder(Handle loader_or_mirror) { 554 if (loader_or_mirror() != NULL) { 555 assert(_holder.is_null(), "never replace holders"); 556 _holder = WeakHandle<vm_class_loader_data>::create(loader_or_mirror); 557 } 558 } 559 560 // Remove a klass from the _klasses list for scratch_class during redefinition 561 // or parsed class in the case of an error. 562 void ClassLoaderData::remove_class(Klass* scratch_class) { 563 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 564 565 // Adjust global class iterator. 566 static_klass_iterator.adjust_saved_class(scratch_class); 567 568 Klass* prev = NULL; 569 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 570 if (k == scratch_class) { 571 if (prev == NULL) { 572 _klasses = k->next_link(); 573 } else { 574 Klass* next = k->next_link(); 575 prev->set_next_link(next); 576 } 577 578 if (k->is_array_klass()) { 579 ClassLoaderDataGraph::dec_array_classes(1); 580 } else { 581 ClassLoaderDataGraph::dec_instance_classes(1); 582 } 583 584 return; 585 } 586 prev = k; 587 assert(k != k->next_link(), "no loops!"); 588 } 589 ShouldNotReachHere(); // should have found this class!! 590 } 591 592 void ClassLoaderData::unload() { 593 _unloading = true; 594 595 LogTarget(Debug, class, loader, data) lt; 596 if (lt.is_enabled()) { 597 ResourceMark rm; 598 LogStream ls(lt); 599 ls.print("unload"); 600 print_value_on(&ls); 601 ls.cr(); 602 } 603 604 // Some items on the _deallocate_list need to free their C heap structures 605 // if they are not already on the _klasses list. 606 unload_deallocate_list(); 607 608 // Tell serviceability tools these classes are unloading 609 // after erroneous classes are released. 610 classes_do(InstanceKlass::notify_unload_class); 611 612 // Clean up global class iterator for compiler 613 static_klass_iterator.adjust_saved_class(this); 614 } 615 616 ModuleEntryTable* ClassLoaderData::modules() { 617 // Lazily create the module entry table at first request. 618 // Lock-free access requires load_acquire. 619 ModuleEntryTable* modules = OrderAccess::load_acquire(&_modules); 620 if (modules == NULL) { 621 MutexLocker m1(Module_lock); 622 // Check if _modules got allocated while we were waiting for this lock. 623 if ((modules = _modules) == NULL) { 624 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size); 625 626 { 627 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag); 628 // Ensure _modules is stable, since it is examined without a lock 629 OrderAccess::release_store(&_modules, modules); 630 } 631 } 632 } 633 return modules; 634 } 635 636 const int _boot_loader_dictionary_size = 1009; 637 const int _default_loader_dictionary_size = 107; 638 639 Dictionary* ClassLoaderData::create_dictionary() { 640 assert(!is_anonymous(), "anonymous class loader data do not have a dictionary"); 641 int size; 642 bool resizable = false; 643 if (_the_null_class_loader_data == NULL) { 644 size = _boot_loader_dictionary_size; 645 resizable = true; 646 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) { 647 size = 1; // there's only one class in relection class loader and no initiated classes 648 } else if (is_system_class_loader_data()) { 649 size = _boot_loader_dictionary_size; 650 resizable = true; 651 } else { 652 size = _default_loader_dictionary_size; 653 resizable = true; 654 } 655 if (!DynamicallyResizeSystemDictionaries || DumpSharedSpaces || UseSharedSpaces) { 656 resizable = false; 657 } 658 return new Dictionary(this, size, resizable); 659 } 660 661 // Tell the GC to keep this klass alive while iterating ClassLoaderDataGraph 662 oop ClassLoaderData::holder_phantom() const { 663 // A klass that was previously considered dead can be looked up in the 664 // CLD/SD, and its _java_mirror or _class_loader can be stored in a root 665 // or a reachable object making it alive again. The SATB part of G1 needs 666 // to get notified about this potential resurrection, otherwise the marking 667 // might not find the object. 668 if (!_holder.is_null()) { // NULL class_loader 669 return _holder.resolve(); 670 } else { 671 return NULL; 672 } 673 } 674 675 // Unloading support 676 bool ClassLoaderData::is_alive() const { 677 bool alive = keep_alive() // null class loader and incomplete anonymous klasses. 678 || (_holder.peek() != NULL); // and not cleaned by the GC weak handle processing. 679 680 return alive; 681 } 682 683 class ReleaseKlassClosure: public KlassClosure { 684 private: 685 size_t _instance_class_released; 686 size_t _array_class_released; 687 public: 688 ReleaseKlassClosure() : _instance_class_released(0), _array_class_released(0) { } 689 690 size_t instance_class_released() const { return _instance_class_released; } 691 size_t array_class_released() const { return _array_class_released; } 692 693 void do_klass(Klass* k) { 694 if (k->is_array_klass()) { 695 _array_class_released ++; 696 } else { 697 assert(k->is_instance_klass(), "Must be"); 698 _instance_class_released ++; 699 InstanceKlass::release_C_heap_structures(InstanceKlass::cast(k)); 700 } 701 } 702 }; 703 704 ClassLoaderData::~ClassLoaderData() { 705 // Release C heap structures for all the classes. 706 ReleaseKlassClosure cl; 707 classes_do(&cl); 708 709 ClassLoaderDataGraph::dec_array_classes(cl.array_class_released()); 710 ClassLoaderDataGraph::dec_instance_classes(cl.instance_class_released()); 711 712 // Release the WeakHandle 713 _holder.release(); 714 715 // Release C heap allocated hashtable for all the packages. 716 if (_packages != NULL) { 717 // Destroy the table itself 718 delete _packages; 719 _packages = NULL; 720 } 721 722 // Release C heap allocated hashtable for all the modules. 723 if (_modules != NULL) { 724 // Destroy the table itself 725 delete _modules; 726 _modules = NULL; 727 } 728 729 // Release C heap allocated hashtable for the dictionary 730 if (_dictionary != NULL) { 731 // Destroy the table itself 732 delete _dictionary; 733 _dictionary = NULL; 734 } 735 736 if (_unnamed_module != NULL) { 737 _unnamed_module->delete_unnamed_module(); 738 _unnamed_module = NULL; 739 } 740 741 // release the metaspace 742 ClassLoaderMetaspace *m = _metaspace; 743 if (m != NULL) { 744 _metaspace = NULL; 745 delete m; 746 } 747 // Clear all the JNI handles for methods 748 // These aren't deallocated and are going to look like a leak, but that's 749 // needed because we can't really get rid of jmethodIDs because we don't 750 // know when native code is going to stop using them. The spec says that 751 // they're "invalid" but existing programs likely rely on their being 752 // NULL after class unloading. 753 if (_jmethod_ids != NULL) { 754 Method::clear_jmethod_ids(this); 755 } 756 // Delete lock 757 delete _metaspace_lock; 758 759 // Delete free list 760 if (_deallocate_list != NULL) { 761 delete _deallocate_list; 762 } 763 } 764 765 // Returns true if this class loader data is for the app class loader 766 // or a user defined system class loader. (Note that the class loader 767 // data may be anonymous.) 768 bool ClassLoaderData::is_system_class_loader_data() const { 769 return SystemDictionary::is_system_class_loader(class_loader()); 770 } 771 772 // Returns true if this class loader data is for the platform class loader. 773 // (Note that the class loader data may be anonymous.) 774 bool ClassLoaderData::is_platform_class_loader_data() const { 775 return SystemDictionary::is_platform_class_loader(class_loader()); 776 } 777 778 // Returns true if the class loader for this class loader data is one of 779 // the 3 builtin (boot application/system or platform) class loaders, 780 // including a user-defined system class loader. Note that if the class 781 // loader data is for an anonymous class then it may get freed by a GC 782 // even if its class loader is one of these loaders. 783 bool ClassLoaderData::is_builtin_class_loader_data() const { 784 return (is_boot_class_loader_data() || 785 SystemDictionary::is_system_class_loader(class_loader()) || 786 SystemDictionary::is_platform_class_loader(class_loader())); 787 } 788 789 // Returns true if this class loader data is a class loader data 790 // that is not ever freed by a GC. It must be one of the builtin 791 // class loaders and not anonymous. 792 bool ClassLoaderData::is_permanent_class_loader_data() const { 793 return is_builtin_class_loader_data() && !is_anonymous(); 794 } 795 796 ClassLoaderMetaspace* ClassLoaderData::metaspace_non_null() { 797 // If the metaspace has not been allocated, create a new one. Might want 798 // to create smaller arena for Reflection class loaders also. 799 // The reason for the delayed allocation is because some class loaders are 800 // simply for delegating with no metadata of their own. 801 // Lock-free access requires load_acquire. 802 ClassLoaderMetaspace* metaspace = OrderAccess::load_acquire(&_metaspace); 803 if (metaspace == NULL) { 804 MutexLockerEx ml(_metaspace_lock, Mutex::_no_safepoint_check_flag); 805 // Check if _metaspace got allocated while we were waiting for this lock. 806 if ((metaspace = _metaspace) == NULL) { 807 if (this == the_null_class_loader_data()) { 808 assert (class_loader() == NULL, "Must be"); 809 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::BootMetaspaceType); 810 } else if (is_anonymous()) { 811 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType); 812 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) { 813 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType); 814 } else { 815 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::StandardMetaspaceType); 816 } 817 // Ensure _metaspace is stable, since it is examined without a lock 818 OrderAccess::release_store(&_metaspace, metaspace); 819 } 820 } 821 return metaspace; 822 } 823 824 OopHandle ClassLoaderData::add_handle(Handle h) { 825 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 826 record_modified_oops(); 827 return OopHandle(_handles.add(h())); 828 } 829 830 void ClassLoaderData::remove_handle(OopHandle h) { 831 assert(!is_unloading(), "Do not remove a handle for a CLD that is unloading"); 832 oop* ptr = h.ptr_raw(); 833 if (ptr != NULL) { 834 assert(_handles.owner_of(ptr), "Got unexpected handle " PTR_FORMAT, p2i(ptr)); 835 NativeAccess<>::oop_store(ptr, oop(NULL)); 836 } 837 } 838 839 void ClassLoaderData::init_handle_locked(OopHandle& dest, Handle h) { 840 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 841 if (dest.resolve() != NULL) { 842 return; 843 } else { 844 dest = _handles.add(h()); 845 } 846 } 847 848 // Add this metadata pointer to be freed when it's safe. This is only during 849 // class unloading because Handles might point to this metadata field. 850 void ClassLoaderData::add_to_deallocate_list(Metadata* m) { 851 // Metadata in shared region isn't deleted. 852 if (!m->is_shared()) { 853 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 854 if (_deallocate_list == NULL) { 855 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true); 856 } 857 _deallocate_list->append_if_missing(m); 858 } 859 } 860 861 // Deallocate free metadata on the free list. How useful the PermGen was! 862 void ClassLoaderData::free_deallocate_list() { 863 // Don't need lock, at safepoint 864 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 865 assert(!is_unloading(), "only called for ClassLoaderData that are not unloading"); 866 if (_deallocate_list == NULL) { 867 return; 868 } 869 // Go backwards because this removes entries that are freed. 870 for (int i = _deallocate_list->length() - 1; i >= 0; i--) { 871 Metadata* m = _deallocate_list->at(i); 872 if (!m->on_stack()) { 873 _deallocate_list->remove_at(i); 874 // There are only three types of metadata that we deallocate directly. 875 // Cast them so they can be used by the template function. 876 if (m->is_method()) { 877 MetadataFactory::free_metadata(this, (Method*)m); 878 } else if (m->is_constantPool()) { 879 MetadataFactory::free_metadata(this, (ConstantPool*)m); 880 } else if (m->is_klass()) { 881 MetadataFactory::free_metadata(this, (InstanceKlass*)m); 882 } else { 883 ShouldNotReachHere(); 884 } 885 } else { 886 // Metadata is alive. 887 // If scratch_class is on stack then it shouldn't be on this list! 888 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(), 889 "scratch classes on this list should be dead"); 890 // Also should assert that other metadata on the list was found in handles. 891 } 892 } 893 } 894 895 // This is distinct from free_deallocate_list. For class loader data that are 896 // unloading, this frees the C heap memory for items on the list, and unlinks 897 // scratch or error classes so that unloading events aren't triggered for these 898 // classes. The metadata is removed with the unloading metaspace. 899 // There isn't C heap memory allocated for methods, so nothing is done for them. 900 void ClassLoaderData::unload_deallocate_list() { 901 // Don't need lock, at safepoint 902 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 903 assert(is_unloading(), "only called for ClassLoaderData that are unloading"); 904 if (_deallocate_list == NULL) { 905 return; 906 } 907 // Go backwards because this removes entries that are freed. 908 for (int i = _deallocate_list->length() - 1; i >= 0; i--) { 909 Metadata* m = _deallocate_list->at(i); 910 assert (!m->on_stack(), "wouldn't be unloading if this were so"); 911 _deallocate_list->remove_at(i); 912 if (m->is_constantPool()) { 913 ((ConstantPool*)m)->release_C_heap_structures(); 914 } else if (m->is_klass()) { 915 InstanceKlass* ik = (InstanceKlass*)m; 916 // also releases ik->constants() C heap memory 917 InstanceKlass::release_C_heap_structures(ik); 918 // Remove the class so unloading events aren't triggered for 919 // this class (scratch or error class) in do_unloading(). 920 remove_class(ik); 921 } 922 } 923 } 924 925 // These anonymous class loaders are to contain classes used for JSR292 926 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(Handle loader) { 927 // Add a new class loader data to the graph. 928 return ClassLoaderDataGraph::add(loader, true); 929 } 930 931 // Caller needs ResourceMark 932 // If the class loader's _name has not been explicitly set, the class loader's 933 // qualified class name is returned. 934 const char* ClassLoaderData::loader_name() const { 935 if (_class_loader_klass == NULL) { 936 return BOOTSTRAP_LOADER_NAME; 937 } else if (_name != NULL) { 938 return _name->as_C_string(); 939 } else { 940 return _class_loader_klass->external_name(); 941 } 942 } 943 944 // Caller needs ResourceMark 945 // Format of the _name_and_id is as follows: 946 // If the defining loader has a name explicitly set then '<loader-name>' @<id> 947 // If the defining loader has no name then <qualified-class-name> @<id> 948 // If built-in loader, then omit '@<id>' as there is only one instance. 949 const char* ClassLoaderData::loader_name_and_id() const { 950 if (_class_loader_klass == NULL) { 951 return "'" BOOTSTRAP_LOADER_NAME "'"; 952 } else if (_name_and_id != NULL) { 953 return _name_and_id->as_C_string(); 954 } else { 955 // May be called in a race before _name_and_id is initialized. 956 return _class_loader_klass->external_name(); 957 } 958 } 959 960 void ClassLoaderData::print_value_on(outputStream* out) const { 961 if (!is_unloading() && class_loader() != NULL) { 962 out->print("loader data: " INTPTR_FORMAT " for instance ", p2i(this)); 963 class_loader()->print_value_on(out); // includes loader_name_and_id() and address of class loader instance 964 } else { 965 // loader data: 0xsomeaddr of 'bootstrap' 966 out->print("loader data: " INTPTR_FORMAT " of %s", p2i(this), loader_name_and_id()); 967 } 968 if (is_anonymous()) { 969 out->print(" anonymous"); 970 } 971 } 972 973 #ifndef PRODUCT 974 void ClassLoaderData::print_on(outputStream* out) const { 975 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: %s {", 976 p2i(this), p2i(_class_loader.ptr_raw()), loader_name_and_id()); 977 if (is_anonymous()) out->print(" anonymous"); 978 if (claimed()) out->print(" claimed"); 979 if (is_unloading()) out->print(" unloading"); 980 out->print(" metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null())); 981 982 if (_jmethod_ids != NULL) { 983 Method::print_jmethod_ids(this, out); 984 } 985 out->print(" handles count %d", _handles.count()); 986 out->print(" dependencies %d", _dependency_count); 987 out->print_cr("}"); 988 } 989 #endif // PRODUCT 990 991 void ClassLoaderData::verify() { 992 assert_locked_or_safepoint(_metaspace_lock); 993 oop cl = class_loader(); 994 995 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same"); 996 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be"); 997 998 // Verify the integrity of the allocated space. 999 if (metaspace_or_null() != NULL) { 1000 metaspace_or_null()->verify(); 1001 } 1002 1003 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 1004 guarantee(k->class_loader_data() == this, "Must be the same"); 1005 k->verify(); 1006 assert(k != k->next_link(), "no loops!"); 1007 } 1008 } 1009 1010 bool ClassLoaderData::contains_klass(Klass* klass) { 1011 // Lock-free access requires load_acquire 1012 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 1013 if (k == klass) return true; 1014 } 1015 return false; 1016 } 1017 1018 1019 // GC root of class loader data created. 1020 ClassLoaderData* ClassLoaderDataGraph::_head = NULL; 1021 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL; 1022 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL; 1023 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL; 1024 1025 bool ClassLoaderDataGraph::_should_purge = false; 1026 bool ClassLoaderDataGraph::_metaspace_oom = false; 1027 1028 // Add a new class loader data node to the list. Assign the newly created 1029 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field 1030 ClassLoaderData* ClassLoaderDataGraph::add_to_graph(Handle loader, bool is_anonymous) { 1031 NoSafepointVerifier no_safepoints; // we mustn't GC until we've installed the 1032 // ClassLoaderData in the graph since the CLD 1033 // contains oops in _handles that must be walked. 1034 1035 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous); 1036 1037 if (!is_anonymous) { 1038 // First, Atomically set it 1039 ClassLoaderData* old = java_lang_ClassLoader::cmpxchg_loader_data(cld, loader(), NULL); 1040 if (old != NULL) { 1041 delete cld; 1042 // Returns the data. 1043 return old; 1044 } 1045 } 1046 1047 // We won the race, and therefore the task of adding the data to the list of 1048 // class loader data 1049 ClassLoaderData** list_head = &_head; 1050 ClassLoaderData* next = _head; 1051 1052 do { 1053 cld->set_next(next); 1054 ClassLoaderData* exchanged = Atomic::cmpxchg(cld, list_head, next); 1055 if (exchanged == next) { 1056 LogTarget(Debug, class, loader, data) lt; 1057 if (lt.is_enabled()) { 1058 ResourceMark rm; 1059 LogStream ls(lt); 1060 ls.print("create "); 1061 cld->print_value_on(&ls); 1062 ls.cr(); 1063 } 1064 return cld; 1065 } 1066 next = exchanged; 1067 } while (true); 1068 } 1069 1070 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous) { 1071 ClassLoaderData* loader_data = add_to_graph(loader, is_anonymous); 1072 // Initialize _name and _name_and_id after the loader data is added to the 1073 // CLDG because adding the Symbol for _name and _name_and_id might safepoint. 1074 if (loader.not_null()) { 1075 loader_data->initialize_name(loader); 1076 } 1077 return loader_data; 1078 } 1079 1080 void ClassLoaderDataGraph::oops_do(OopClosure* f, bool must_claim) { 1081 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 1082 cld->oops_do(f, must_claim); 1083 } 1084 } 1085 1086 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, bool must_claim) { 1087 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 1088 if (cld->keep_alive()) { 1089 cld->oops_do(f, must_claim); 1090 } 1091 } 1092 } 1093 1094 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, bool must_claim) { 1095 if (ClassUnloading) { 1096 keep_alive_oops_do(f, must_claim); 1097 } else { 1098 oops_do(f, must_claim); 1099 } 1100 } 1101 1102 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) { 1103 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) { 1104 cl->do_cld(cld); 1105 } 1106 } 1107 1108 void ClassLoaderDataGraph::cld_unloading_do(CLDClosure* cl) { 1109 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 1110 // Only walk the head until any clds not purged from prior unloading 1111 // (CMS doesn't purge right away). 1112 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) { 1113 assert(cld->is_unloading(), "invariant"); 1114 cl->do_cld(cld); 1115 } 1116 } 1117 1118 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) { 1119 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) { 1120 CLDClosure* closure = cld->keep_alive() ? strong : weak; 1121 if (closure != NULL) { 1122 closure->do_cld(cld); 1123 } 1124 } 1125 } 1126 1127 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) { 1128 roots_cld_do(cl, NULL); 1129 } 1130 1131 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) { 1132 if (ClassUnloading) { 1133 keep_alive_cld_do(cl); 1134 } else { 1135 cld_do(cl); 1136 } 1137 } 1138 1139 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) { 1140 Thread* thread = Thread::current(); 1141 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 1142 Handle holder(thread, cld->holder_phantom()); 1143 cld->classes_do(klass_closure); 1144 } 1145 } 1146 1147 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) { 1148 Thread* thread = Thread::current(); 1149 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 1150 Handle holder(thread, cld->holder_phantom()); 1151 cld->classes_do(f); 1152 } 1153 } 1154 1155 void ClassLoaderDataGraph::methods_do(void f(Method*)) { 1156 Thread* thread = Thread::current(); 1157 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 1158 Handle holder(thread, cld->holder_phantom()); 1159 cld->methods_do(f); 1160 } 1161 } 1162 1163 void ClassLoaderDataGraph::modules_do(void f(ModuleEntry*)) { 1164 assert_locked_or_safepoint(Module_lock); 1165 Thread* thread = Thread::current(); 1166 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 1167 Handle holder(thread, cld->holder_phantom()); 1168 cld->modules_do(f); 1169 } 1170 } 1171 1172 void ClassLoaderDataGraph::modules_unloading_do(void f(ModuleEntry*)) { 1173 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 1174 // Only walk the head until any clds not purged from prior unloading 1175 // (CMS doesn't purge right away). 1176 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) { 1177 assert(cld->is_unloading(), "invariant"); 1178 cld->modules_do(f); 1179 } 1180 } 1181 1182 void ClassLoaderDataGraph::packages_do(void f(PackageEntry*)) { 1183 assert_locked_or_safepoint(Module_lock); 1184 Thread* thread = Thread::current(); 1185 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 1186 Handle holder(thread, cld->holder_phantom()); 1187 cld->packages_do(f); 1188 } 1189 } 1190 1191 void ClassLoaderDataGraph::packages_unloading_do(void f(PackageEntry*)) { 1192 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 1193 // Only walk the head until any clds not purged from prior unloading 1194 // (CMS doesn't purge right away). 1195 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) { 1196 assert(cld->is_unloading(), "invariant"); 1197 cld->packages_do(f); 1198 } 1199 } 1200 1201 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) { 1202 Thread* thread = Thread::current(); 1203 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 1204 Handle holder(thread, cld->holder_phantom()); 1205 cld->loaded_classes_do(klass_closure); 1206 } 1207 } 1208 1209 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) { 1210 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 1211 // Only walk the head until any clds not purged from prior unloading 1212 // (CMS doesn't purge right away). 1213 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) { 1214 assert(cld->is_unloading(), "invariant"); 1215 cld->classes_do(f); 1216 } 1217 } 1218 1219 #define FOR_ALL_DICTIONARY(X) for (ClassLoaderData* X = _head; X != NULL; X = X->next()) \ 1220 if (X->dictionary() != NULL) 1221 1222 // Walk classes in the loaded class dictionaries in various forms. 1223 // Only walks the classes defined in this class loader. 1224 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*)) { 1225 Thread* thread = Thread::current(); 1226 FOR_ALL_DICTIONARY(cld) { 1227 Handle holder(thread, cld->holder_phantom()); 1228 cld->dictionary()->classes_do(f); 1229 } 1230 } 1231 1232 // Only walks the classes defined in this class loader. 1233 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*, TRAPS), TRAPS) { 1234 Thread* thread = Thread::current(); 1235 FOR_ALL_DICTIONARY(cld) { 1236 Handle holder(thread, cld->holder_phantom()); 1237 cld->dictionary()->classes_do(f, CHECK); 1238 } 1239 } 1240 1241 // Walks all entries in the dictionary including entries initiated by this class loader. 1242 void ClassLoaderDataGraph::dictionary_all_entries_do(void f(InstanceKlass*, ClassLoaderData*)) { 1243 Thread* thread = Thread::current(); 1244 FOR_ALL_DICTIONARY(cld) { 1245 Handle holder(thread, cld->holder_phantom()); 1246 cld->dictionary()->all_entries_do(f); 1247 } 1248 } 1249 1250 void ClassLoaderDataGraph::verify_dictionary() { 1251 FOR_ALL_DICTIONARY(cld) { 1252 cld->dictionary()->verify(); 1253 } 1254 } 1255 1256 void ClassLoaderDataGraph::print_dictionary(outputStream* st) { 1257 FOR_ALL_DICTIONARY(cld) { 1258 st->print("Dictionary for "); 1259 cld->print_value_on(st); 1260 st->cr(); 1261 cld->dictionary()->print_on(st); 1262 st->cr(); 1263 } 1264 } 1265 1266 void ClassLoaderDataGraph::print_dictionary_statistics(outputStream* st) { 1267 FOR_ALL_DICTIONARY(cld) { 1268 ResourceMark rm; 1269 stringStream tempst; 1270 tempst.print("System Dictionary for %s class loader", cld->loader_name_and_id()); 1271 cld->dictionary()->print_table_statistics(st, tempst.as_string()); 1272 } 1273 } 1274 1275 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() { 1276 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?"); 1277 1278 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>(); 1279 1280 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true); 1281 ClassLoaderData* curr = _head; 1282 while (curr != _saved_head) { 1283 if (!curr->claimed()) { 1284 array->push(curr); 1285 LogTarget(Debug, class, loader, data) lt; 1286 if (lt.is_enabled()) { 1287 LogStream ls(lt); 1288 ls.print("found new CLD: "); 1289 curr->print_value_on(&ls); 1290 ls.cr(); 1291 } 1292 } 1293 1294 curr = curr->_next; 1295 } 1296 1297 return array; 1298 } 1299 1300 #ifndef PRODUCT 1301 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) { 1302 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 1303 if (loader_data == data) { 1304 return true; 1305 } 1306 } 1307 1308 return false; 1309 } 1310 #endif // PRODUCT 1311 1312 #if INCLUDE_JFR 1313 static Ticks class_unload_time; 1314 static void post_class_unload_event(Klass* const k) { 1315 assert(k != NULL, "invariant"); 1316 EventClassUnload event(UNTIMED); 1317 event.set_endtime(class_unload_time); 1318 event.set_unloadedClass(k); 1319 event.set_definingClassLoader(k->class_loader_data()); 1320 event.commit(); 1321 } 1322 1323 static void post_class_unload_events() { 1324 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 1325 if (Jfr::is_enabled()) { 1326 if (EventClassUnload::is_enabled()) { 1327 class_unload_time = Ticks::now(); 1328 ClassLoaderDataGraph::classes_unloading_do(&post_class_unload_event); 1329 } 1330 Jfr::on_unloading_classes(); 1331 } 1332 } 1333 #endif // INCLUDE_JFR 1334 1335 // Move class loader data from main list to the unloaded list for unloading 1336 // and deallocation later. 1337 bool ClassLoaderDataGraph::do_unloading(bool clean_previous_versions) { 1338 1339 ClassLoaderData* data = _head; 1340 ClassLoaderData* prev = NULL; 1341 bool seen_dead_loader = false; 1342 uint loaders_processed = 0; 1343 uint loaders_removed = 0; 1344 1345 // Mark metadata seen on the stack only so we can delete unneeded entries. 1346 // Only walk all metadata, including the expensive code cache walk, for Full GC 1347 // and only if class redefinition and if there's previous versions of 1348 // Klasses to delete. 1349 bool walk_all_metadata = clean_previous_versions && 1350 JvmtiExport::has_redefined_a_class() && 1351 InstanceKlass::has_previous_versions_and_reset(); 1352 MetadataOnStackMark md_on_stack(walk_all_metadata); 1353 1354 // Save previous _unloading pointer for CMS which may add to unloading list before 1355 // purging and we don't want to rewalk the previously unloaded class loader data. 1356 _saved_unloading = _unloading; 1357 1358 data = _head; 1359 while (data != NULL) { 1360 if (data->is_alive()) { 1361 // clean metaspace 1362 if (walk_all_metadata) { 1363 data->classes_do(InstanceKlass::purge_previous_versions); 1364 } 1365 data->free_deallocate_list(); 1366 prev = data; 1367 data = data->next(); 1368 loaders_processed++; 1369 continue; 1370 } 1371 seen_dead_loader = true; 1372 loaders_removed++; 1373 ClassLoaderData* dead = data; 1374 dead->unload(); 1375 data = data->next(); 1376 // Remove from loader list. 1377 // This class loader data will no longer be found 1378 // in the ClassLoaderDataGraph. 1379 if (prev != NULL) { 1380 prev->set_next(data); 1381 } else { 1382 assert(dead == _head, "sanity check"); 1383 _head = data; 1384 } 1385 dead->set_next(_unloading); 1386 _unloading = dead; 1387 } 1388 1389 if (seen_dead_loader) { 1390 data = _head; 1391 while (data != NULL) { 1392 // Remove entries in the dictionary of live class loader that have 1393 // initiated loading classes in a dead class loader. 1394 if (data->dictionary() != NULL) { 1395 data->dictionary()->do_unloading(); 1396 } 1397 // Walk a ModuleEntry's reads, and a PackageEntry's exports 1398 // lists to determine if there are modules on those lists that are now 1399 // dead and should be removed. A module's life cycle is equivalent 1400 // to its defining class loader's life cycle. Since a module is 1401 // considered dead if its class loader is dead, these walks must 1402 // occur after each class loader's aliveness is determined. 1403 if (data->packages() != NULL) { 1404 data->packages()->purge_all_package_exports(); 1405 } 1406 if (data->modules_defined()) { 1407 data->modules()->purge_all_module_reads(); 1408 } 1409 data = data->next(); 1410 } 1411 JFR_ONLY(post_class_unload_events();) 1412 } 1413 1414 log_debug(class, loader, data)("do_unloading: loaders processed %u, loaders removed %u", loaders_processed, loaders_removed); 1415 1416 return seen_dead_loader; 1417 } 1418 1419 void ClassLoaderDataGraph::purge() { 1420 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 1421 ClassLoaderData* list = _unloading; 1422 _unloading = NULL; 1423 ClassLoaderData* next = list; 1424 bool classes_unloaded = false; 1425 while (next != NULL) { 1426 ClassLoaderData* purge_me = next; 1427 next = purge_me->next(); 1428 delete purge_me; 1429 classes_unloaded = true; 1430 } 1431 if (classes_unloaded) { 1432 Metaspace::purge(); 1433 set_metaspace_oom(false); 1434 } 1435 } 1436 1437 int ClassLoaderDataGraph::resize_if_needed() { 1438 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 1439 int resized = 0; 1440 if (Dictionary::does_any_dictionary_needs_resizing()) { 1441 FOR_ALL_DICTIONARY(cld) { 1442 if (cld->dictionary()->resize_if_needed()) { 1443 resized++; 1444 } 1445 } 1446 } 1447 return resized; 1448 } 1449 1450 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic() 1451 : _next_klass(NULL) { 1452 ClassLoaderData* cld = ClassLoaderDataGraph::_head; 1453 Klass* klass = NULL; 1454 1455 // Find the first klass in the CLDG. 1456 while (cld != NULL) { 1457 assert_locked_or_safepoint(cld->metaspace_lock()); 1458 klass = cld->_klasses; 1459 if (klass != NULL) { 1460 _next_klass = klass; 1461 return; 1462 } 1463 cld = cld->next(); 1464 } 1465 } 1466 1467 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) { 1468 Klass* next = klass->next_link(); 1469 if (next != NULL) { 1470 return next; 1471 } 1472 1473 // No more klasses in the current CLD. Time to find a new CLD. 1474 ClassLoaderData* cld = klass->class_loader_data(); 1475 assert_locked_or_safepoint(cld->metaspace_lock()); 1476 while (next == NULL) { 1477 cld = cld->next(); 1478 if (cld == NULL) { 1479 break; 1480 } 1481 next = cld->_klasses; 1482 } 1483 1484 return next; 1485 } 1486 1487 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() { 1488 Klass* head = _next_klass; 1489 1490 while (head != NULL) { 1491 Klass* next = next_klass_in_cldg(head); 1492 1493 Klass* old_head = Atomic::cmpxchg(next, &_next_klass, head); 1494 1495 if (old_head == head) { 1496 return head; // Won the CAS. 1497 } 1498 1499 head = old_head; 1500 } 1501 1502 // Nothing more for the iterator to hand out. 1503 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head)); 1504 return NULL; 1505 } 1506 1507 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() { 1508 _data = ClassLoaderDataGraph::_head; 1509 } 1510 1511 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {} 1512 1513 #ifndef PRODUCT 1514 // callable from debugger 1515 extern "C" int print_loader_data_graph() { 1516 ResourceMark rm; 1517 ClassLoaderDataGraph::print_on(tty); 1518 return 0; 1519 } 1520 1521 void ClassLoaderDataGraph::verify() { 1522 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 1523 data->verify(); 1524 } 1525 } 1526 1527 void ClassLoaderDataGraph::print_on(outputStream * const out) { 1528 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 1529 data->print_on(out); 1530 } 1531 } 1532 #endif // PRODUCT