1 /* 2 * Copyright (c) 2012, 2016, 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/javaClasses.hpp" 53 #include "classfile/metadataOnStackMark.hpp" 54 #include "classfile/moduleEntry.hpp" 55 #include "classfile/packageEntry.hpp" 56 #include "classfile/systemDictionary.hpp" 57 #include "code/codeCache.hpp" 58 #include "gc/shared/gcLocker.hpp" 59 #include "logging/log.hpp" 60 #include "memory/metadataFactory.hpp" 61 #include "memory/metaspaceShared.hpp" 62 #include "memory/oopFactory.hpp" 63 #include "memory/resourceArea.hpp" 64 #include "oops/objArrayOop.inline.hpp" 65 #include "oops/oop.inline.hpp" 66 #include "runtime/atomic.inline.hpp" 67 #include "runtime/javaCalls.hpp" 68 #include "runtime/jniHandles.hpp" 69 #include "runtime/mutex.hpp" 70 #include "runtime/orderAccess.hpp" 71 #include "runtime/safepoint.hpp" 72 #include "runtime/synchronizer.hpp" 73 #include "utilities/growableArray.hpp" 74 #include "utilities/macros.hpp" 75 #include "utilities/ostream.hpp" 76 #if INCLUDE_TRACE 77 #include "trace/tracing.hpp" 78 #endif 79 80 // helper function to avoid in-line casts 81 template <typename T> static T* load_ptr_acquire(T* volatile *p) { 82 return static_cast<T*>(OrderAccess::load_ptr_acquire(p)); 83 } 84 85 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL; 86 87 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous, Dependencies dependencies) : 88 _class_loader(h_class_loader()), 89 _is_anonymous(is_anonymous), 90 // An anonymous class loader data doesn't have anything to keep 91 // it from being unloaded during parsing of the anonymous class. 92 // The null-class-loader should always be kept alive. 93 _keep_alive((is_anonymous || h_class_loader.is_null()) ? 1 : 0), 94 _metaspace(NULL), _unloading(false), _klasses(NULL), 95 _modules(NULL), _packages(NULL), 96 _claimed(0), _jmethod_ids(NULL), _handles(NULL), _deallocate_list(NULL), 97 _next(NULL), _dependencies(dependencies), _shared_class_loader_id(-1), 98 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true, 99 Monitor::_safepoint_check_never)) { 100 // empty 101 } 102 103 void ClassLoaderData::init_dependencies(TRAPS) { 104 assert(!Universe::is_fully_initialized(), "should only be called when initializing"); 105 assert(is_the_null_class_loader_data(), "should only call this for the null class loader"); 106 _dependencies.init(CHECK); 107 } 108 109 void ClassLoaderData::Dependencies::init(TRAPS) { 110 // Create empty dependencies array to add to. CMS requires this to be 111 // an oop so that it can track additions via card marks. We think. 112 _list_head = oopFactory::new_objectArray(2, CHECK); 113 } 114 115 bool ClassLoaderData::claim() { 116 if (_claimed == 1) { 117 return false; 118 } 119 120 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0; 121 } 122 123 // Anonymous classes have their own ClassLoaderData that is marked to keep alive 124 // while the class is being parsed, and if the class appears on the module fixup list. 125 // Due to the uniqueness that no other class shares the anonymous class' name or 126 // ClassLoaderData, no other non-GC thread has knowledge of the anonymous class while 127 // it is being defined, therefore _keep_alive is not volatile or atomic. 128 void ClassLoaderData::inc_keep_alive() { 129 assert(_keep_alive >= 0, "Invalid keep alive count"); 130 _keep_alive++; 131 } 132 133 void ClassLoaderData::dec_keep_alive() { 134 assert(_keep_alive > 0, "Invalid keep alive count"); 135 _keep_alive--; 136 } 137 138 void ClassLoaderData::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 139 if (must_claim && !claim()) { 140 return; 141 } 142 143 f->do_oop(&_class_loader); 144 _dependencies.oops_do(f); 145 _handles->oops_do(f); 146 if (klass_closure != NULL) { 147 classes_do(klass_closure); 148 } 149 } 150 151 void ClassLoaderData::Dependencies::oops_do(OopClosure* f) { 152 f->do_oop((oop*)&_list_head); 153 } 154 155 void ClassLoaderData::classes_do(KlassClosure* klass_closure) { 156 // Lock-free access requires load_ptr_acquire 157 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) { 158 klass_closure->do_klass(k); 159 assert(k != k->next_link(), "no loops!"); 160 } 161 } 162 163 void ClassLoaderData::classes_do(void f(Klass * const)) { 164 assert_locked_or_safepoint(_metaspace_lock); 165 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 166 f(k); 167 } 168 } 169 170 void ClassLoaderData::methods_do(void f(Method*)) { 171 // Lock-free access requires load_ptr_acquire 172 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) { 173 if (k->is_instance_klass()) { 174 InstanceKlass::cast(k)->methods_do(f); 175 } 176 } 177 } 178 179 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) { 180 // Lock to avoid classes being modified/added/removed during iteration 181 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 182 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 183 // Do not filter ArrayKlass oops here... 184 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) { 185 klass_closure->do_klass(k); 186 } 187 } 188 } 189 190 void ClassLoaderData::classes_do(void f(InstanceKlass*)) { 191 // Lock-free access requires load_ptr_acquire 192 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) { 193 if (k->is_instance_klass()) { 194 f(InstanceKlass::cast(k)); 195 } 196 assert(k != k->next_link(), "no loops!"); 197 } 198 } 199 200 void ClassLoaderData::modules_do(void f(ModuleEntry*)) { 201 assert_locked_or_safepoint(Module_lock); 202 if (_modules != NULL) { 203 for (int i = 0; i < _modules->table_size(); i++) { 204 for (ModuleEntry* entry = _modules->bucket(i); 205 entry != NULL; 206 entry = entry->next()) { 207 f(entry); 208 } 209 } 210 } 211 } 212 213 void ClassLoaderData::packages_do(void f(PackageEntry*)) { 214 // Lock-free access requires load_ptr_acquire 215 PackageEntryTable* packages = load_ptr_acquire(&_packages); 216 if (packages != NULL) { 217 for (int i = 0; i < packages->table_size(); i++) { 218 for (PackageEntry* entry = packages->bucket(i); 219 entry != NULL; 220 entry = entry->next()) { 221 f(entry); 222 } 223 } 224 } 225 } 226 227 void ClassLoaderData::record_dependency(const Klass* k, TRAPS) { 228 assert(k != NULL, "invariant"); 229 230 ClassLoaderData * const from_cld = this; 231 ClassLoaderData * const to_cld = k->class_loader_data(); 232 233 // Dependency to the null class loader data doesn't need to be recorded 234 // because the null class loader data never goes away. 235 if (to_cld->is_the_null_class_loader_data()) { 236 return; 237 } 238 239 oop to; 240 if (to_cld->is_anonymous()) { 241 // Anonymous class dependencies are through the mirror. 242 to = k->java_mirror(); 243 } else { 244 to = to_cld->class_loader(); 245 246 // If from_cld is anonymous, even if it's class_loader is a parent of 'to' 247 // we still have to add it. The class_loader won't keep from_cld alive. 248 if (!from_cld->is_anonymous()) { 249 // Check that this dependency isn't from the same or parent class_loader 250 oop from = from_cld->class_loader(); 251 252 oop curr = from; 253 while (curr != NULL) { 254 if (curr == to) { 255 return; // this class loader is in the parent list, no need to add it. 256 } 257 curr = java_lang_ClassLoader::parent(curr); 258 } 259 } 260 } 261 262 // It's a dependency we won't find through GC, add it. This is relatively rare 263 // Must handle over GC point. 264 Handle dependency(THREAD, to); 265 from_cld->_dependencies.add(dependency, CHECK); 266 } 267 268 269 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) { 270 // Check first if this dependency is already in the list. 271 // Save a pointer to the last to add to under the lock. 272 objArrayOop ok = _list_head; 273 objArrayOop last = NULL; 274 while (ok != NULL) { 275 last = ok; 276 if (ok->obj_at(0) == dependency()) { 277 // Don't need to add it 278 return; 279 } 280 ok = (objArrayOop)ok->obj_at(1); 281 } 282 283 // Must handle over GC points 284 assert (last != NULL, "dependencies should be initialized"); 285 objArrayHandle last_handle(THREAD, last); 286 287 // Create a new dependency node with fields for (class_loader or mirror, next) 288 objArrayOop deps = oopFactory::new_objectArray(2, CHECK); 289 deps->obj_at_put(0, dependency()); 290 291 // Must handle over GC points 292 objArrayHandle new_dependency(THREAD, deps); 293 294 // Add the dependency under lock 295 locked_add(last_handle, new_dependency, THREAD); 296 } 297 298 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle, 299 objArrayHandle new_dependency, 300 Thread* THREAD) { 301 302 // Have to lock and put the new dependency on the end of the dependency 303 // array so the card mark for CMS sees that this dependency is new. 304 // Can probably do this lock free with some effort. 305 ObjectLocker ol(Handle(THREAD, _list_head), THREAD); 306 307 oop loader_or_mirror = new_dependency->obj_at(0); 308 309 // Since the dependencies are only added, add to the end. 310 objArrayOop end = last_handle(); 311 objArrayOop last = NULL; 312 while (end != NULL) { 313 last = end; 314 // check again if another thread added it to the end. 315 if (end->obj_at(0) == loader_or_mirror) { 316 // Don't need to add it 317 return; 318 } 319 end = (objArrayOop)end->obj_at(1); 320 } 321 assert (last != NULL, "dependencies should be initialized"); 322 // fill in the first element with the oop in new_dependency. 323 if (last->obj_at(0) == NULL) { 324 last->obj_at_put(0, new_dependency->obj_at(0)); 325 } else { 326 last->obj_at_put(1, new_dependency()); 327 } 328 } 329 330 void ClassLoaderDataGraph::clear_claimed_marks() { 331 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 332 cld->clear_claimed(); 333 } 334 } 335 336 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) { 337 { 338 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 339 Klass* old_value = _klasses; 340 k->set_next_link(old_value); 341 // Link the new item into the list, making sure the linked class is stable 342 // since the list can be walked without a lock 343 OrderAccess::release_store_ptr(&_klasses, k); 344 } 345 346 if (publicize && k->class_loader_data() != NULL) { 347 ResourceMark rm; 348 log_trace(class, loader, data)("Adding k: " PTR_FORMAT " %s to CLD: " 349 PTR_FORMAT " loader: " PTR_FORMAT " %s", 350 p2i(k), 351 k->external_name(), 352 p2i(k->class_loader_data()), 353 p2i((void *)k->class_loader()), 354 loader_name()); 355 } 356 } 357 358 // Remove a klass from the _klasses list for scratch_class during redefinition 359 // or parsed class in the case of an error. 360 void ClassLoaderData::remove_class(Klass* scratch_class) { 361 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 362 Klass* prev = NULL; 363 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 364 if (k == scratch_class) { 365 if (prev == NULL) { 366 _klasses = k->next_link(); 367 } else { 368 Klass* next = k->next_link(); 369 prev->set_next_link(next); 370 } 371 return; 372 } 373 prev = k; 374 assert(k != k->next_link(), "no loops!"); 375 } 376 ShouldNotReachHere(); // should have found this class!! 377 } 378 379 void ClassLoaderData::unload() { 380 _unloading = true; 381 382 // Tell serviceability tools these classes are unloading 383 classes_do(InstanceKlass::notify_unload_class); 384 385 if (log_is_enabled(Debug, class, loader, data)) { 386 ResourceMark rm; 387 outputStream* log = Log(class, loader, data)::debug_stream(); 388 log->print(": unload loader data " INTPTR_FORMAT, p2i(this)); 389 log->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()), 390 loader_name()); 391 if (is_anonymous()) { 392 log->print(" for anonymous class " INTPTR_FORMAT " ", p2i(_klasses)); 393 } 394 log->cr(); 395 } 396 397 // In some rare cases items added to this list will not be freed elsewhere. 398 // To keep it simple, just free everything in it here. 399 free_deallocate_list(); 400 } 401 402 PackageEntryTable* ClassLoaderData::packages() { 403 // Lazily create the package entry table at first request. 404 // Lock-free access requires load_ptr_acquire. 405 PackageEntryTable* packages = load_ptr_acquire(&_packages); 406 if (packages == NULL) { 407 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag); 408 // Check if _packages got allocated while we were waiting for this lock. 409 if ((packages = _packages) == NULL) { 410 packages = new PackageEntryTable(PackageEntryTable::_packagetable_entry_size); 411 // Ensure _packages is stable, since it is examined without a lock 412 OrderAccess::release_store_ptr(&_packages, packages); 413 } 414 } 415 return packages; 416 } 417 418 ModuleEntryTable* ClassLoaderData::modules() { 419 // Lazily create the module entry table at first request. 420 // Lock-free access requires load_ptr_acquire. 421 ModuleEntryTable* modules = load_ptr_acquire(&_modules); 422 if (modules == NULL) { 423 MutexLocker m1(Module_lock); 424 // Check if _modules got allocated while we were waiting for this lock. 425 if ((modules = _modules) == NULL) { 426 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size); 427 // Each loader has one unnamed module entry. Create it before 428 // any classes, loaded by this loader, are defined in case 429 // they end up being defined in loader's unnamed module. 430 modules->create_unnamed_module(this); 431 432 { 433 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag); 434 // Ensure _modules is stable, since it is examined without a lock 435 OrderAccess::release_store_ptr(&_modules, modules); 436 } 437 } 438 } 439 return modules; 440 } 441 442 oop ClassLoaderData::keep_alive_object() const { 443 assert_locked_or_safepoint(_metaspace_lock); 444 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive"); 445 return is_anonymous() ? _klasses->java_mirror() : class_loader(); 446 } 447 448 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const { 449 bool alive = keep_alive() // null class loader and incomplete anonymous klasses. 450 || is_alive_closure->do_object_b(keep_alive_object()); 451 452 return alive; 453 } 454 455 456 ClassLoaderData::~ClassLoaderData() { 457 // Release C heap structures for all the classes. 458 classes_do(InstanceKlass::release_C_heap_structures); 459 460 // Release C heap allocated hashtable for all the packages. 461 if (_packages != NULL) { 462 // Destroy the table itself 463 delete _packages; 464 _packages = NULL; 465 } 466 467 // Release C heap allocated hashtable for all the modules. 468 if (_modules != NULL) { 469 // Destroy the table itself 470 delete _modules; 471 _modules = NULL; 472 } 473 474 // release the metaspace 475 Metaspace *m = _metaspace; 476 if (m != NULL) { 477 _metaspace = NULL; 478 delete m; 479 } 480 // release the handles 481 if (_handles != NULL) { 482 JNIHandleBlock::release_block(_handles); 483 _handles = NULL; 484 } 485 486 // Clear all the JNI handles for methods 487 // These aren't deallocated and are going to look like a leak, but that's 488 // needed because we can't really get rid of jmethodIDs because we don't 489 // know when native code is going to stop using them. The spec says that 490 // they're "invalid" but existing programs likely rely on their being 491 // NULL after class unloading. 492 if (_jmethod_ids != NULL) { 493 Method::clear_jmethod_ids(this); 494 } 495 // Delete lock 496 delete _metaspace_lock; 497 498 // Delete free list 499 if (_deallocate_list != NULL) { 500 delete _deallocate_list; 501 } 502 } 503 504 /** 505 * Returns true if this class loader data is for the platform class loader. 506 */ 507 bool ClassLoaderData::is_platform_class_loader_data() const { 508 return SystemDictionary::is_platform_class_loader(class_loader()); 509 } 510 511 Metaspace* ClassLoaderData::metaspace_non_null() { 512 assert(!DumpSharedSpaces, "wrong metaspace!"); 513 // If the metaspace has not been allocated, create a new one. Might want 514 // to create smaller arena for Reflection class loaders also. 515 // The reason for the delayed allocation is because some class loaders are 516 // simply for delegating with no metadata of their own. 517 // Lock-free access requires load_ptr_acquire. 518 Metaspace* metaspace = load_ptr_acquire(&_metaspace); 519 if (metaspace == NULL) { 520 MutexLockerEx ml(_metaspace_lock, Mutex::_no_safepoint_check_flag); 521 // Check if _metaspace got allocated while we were waiting for this lock. 522 if ((metaspace = _metaspace) == NULL) { 523 if (this == the_null_class_loader_data()) { 524 assert (class_loader() == NULL, "Must be"); 525 metaspace = new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType); 526 } else if (is_anonymous()) { 527 if (class_loader() != NULL) { 528 log_trace(class, loader, data)("is_anonymous: %s", class_loader()->klass()->internal_name()); 529 } 530 metaspace = new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType); 531 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) { 532 if (class_loader() != NULL) { 533 log_trace(class, loader, data)("is_reflection: %s", class_loader()->klass()->internal_name()); 534 } 535 metaspace = new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType); 536 } else { 537 metaspace = new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType); 538 } 539 // Ensure _metaspace is stable, since it is examined without a lock 540 OrderAccess::release_store_ptr(&_metaspace, metaspace); 541 } 542 } 543 return metaspace; 544 } 545 546 JNIHandleBlock* ClassLoaderData::handles() const { return _handles; } 547 void ClassLoaderData::set_handles(JNIHandleBlock* handles) { _handles = handles; } 548 549 jobject ClassLoaderData::add_handle(Handle h) { 550 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 551 if (handles() == NULL) { 552 set_handles(JNIHandleBlock::allocate_block()); 553 } 554 return handles()->allocate_handle(h()); 555 } 556 557 void ClassLoaderData::remove_handle(jobject h) { 558 _handles->release_handle(h); 559 } 560 561 // Add this metadata pointer to be freed when it's safe. This is only during 562 // class unloading because Handles might point to this metadata field. 563 void ClassLoaderData::add_to_deallocate_list(Metadata* m) { 564 // Metadata in shared region isn't deleted. 565 if (!m->is_shared()) { 566 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 567 if (_deallocate_list == NULL) { 568 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true); 569 } 570 _deallocate_list->append_if_missing(m); 571 } 572 } 573 574 // Deallocate free metadata on the free list. How useful the PermGen was! 575 void ClassLoaderData::free_deallocate_list() { 576 // Don't need lock, at safepoint 577 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 578 if (_deallocate_list == NULL) { 579 return; 580 } 581 // Go backwards because this removes entries that are freed. 582 for (int i = _deallocate_list->length() - 1; i >= 0; i--) { 583 Metadata* m = _deallocate_list->at(i); 584 if (!m->on_stack()) { 585 _deallocate_list->remove_at(i); 586 // There are only three types of metadata that we deallocate directly. 587 // Cast them so they can be used by the template function. 588 if (m->is_method()) { 589 MetadataFactory::free_metadata(this, (Method*)m); 590 } else if (m->is_constantPool()) { 591 MetadataFactory::free_metadata(this, (ConstantPool*)m); 592 } else if (m->is_klass()) { 593 MetadataFactory::free_metadata(this, (InstanceKlass*)m); 594 } else { 595 ShouldNotReachHere(); 596 } 597 } else { 598 // Metadata is alive. 599 // If scratch_class is on stack then it shouldn't be on this list! 600 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(), 601 "scratch classes on this list should be dead"); 602 // Also should assert that other metadata on the list was found in handles. 603 } 604 } 605 } 606 607 // These anonymous class loaders are to contain classes used for JSR292 608 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) { 609 // Add a new class loader data to the graph. 610 return ClassLoaderDataGraph::add(loader, true, THREAD); 611 } 612 613 const char* ClassLoaderData::loader_name() { 614 // Handles null class loader 615 return SystemDictionary::loader_name(class_loader()); 616 } 617 618 #ifndef PRODUCT 619 // Define to dump klasses 620 #undef CLD_DUMP_KLASSES 621 622 void ClassLoaderData::dump(outputStream * const out) { 623 ResourceMark rm; 624 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: " PTR_FORMAT " %s {", 625 p2i(this), p2i((void *)class_loader()), 626 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name()); 627 if (claimed()) out->print(" claimed "); 628 if (is_unloading()) out->print(" unloading "); 629 out->print(" handles " INTPTR_FORMAT, p2i(handles())); 630 out->cr(); 631 if (metaspace_or_null() != NULL) { 632 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null())); 633 metaspace_or_null()->dump(out); 634 } else { 635 out->print_cr("metaspace: NULL"); 636 } 637 638 #ifdef CLD_DUMP_KLASSES 639 if (Verbose) { 640 ResourceMark rm; 641 Klass* k = _klasses; 642 while (k != NULL) { 643 out->print_cr("klass " PTR_FORMAT ", %s, CT: %d, MUT: %d", k, k->name()->as_C_string(), 644 k->has_modified_oops(), k->has_accumulated_modified_oops()); 645 assert(k != k->next_link(), "no loops!"); 646 k = k->next_link(); 647 } 648 } 649 #endif // CLD_DUMP_KLASSES 650 #undef CLD_DUMP_KLASSES 651 if (_jmethod_ids != NULL) { 652 Method::print_jmethod_ids(this, out); 653 } 654 out->print_cr("}"); 655 } 656 #endif // PRODUCT 657 658 void ClassLoaderData::verify() { 659 assert_locked_or_safepoint(_metaspace_lock); 660 oop cl = class_loader(); 661 662 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same"); 663 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be"); 664 665 // Verify the integrity of the allocated space. 666 if (metaspace_or_null() != NULL) { 667 metaspace_or_null()->verify(); 668 } 669 670 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 671 guarantee(k->class_loader_data() == this, "Must be the same"); 672 k->verify(); 673 assert(k != k->next_link(), "no loops!"); 674 } 675 } 676 677 bool ClassLoaderData::contains_klass(Klass* klass) { 678 // Lock-free access requires load_ptr_acquire 679 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) { 680 if (k == klass) return true; 681 } 682 return false; 683 } 684 685 686 // GC root of class loader data created. 687 ClassLoaderData* ClassLoaderDataGraph::_head = NULL; 688 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL; 689 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL; 690 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL; 691 692 bool ClassLoaderDataGraph::_should_purge = false; 693 bool ClassLoaderDataGraph::_metaspace_oom = false; 694 695 // Add a new class loader data node to the list. Assign the newly created 696 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field 697 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) { 698 // We need to allocate all the oops for the ClassLoaderData before allocating the 699 // actual ClassLoaderData object. 700 ClassLoaderData::Dependencies dependencies(CHECK_NULL); 701 702 NoSafepointVerifier no_safepoints; // we mustn't GC until we've installed the 703 // ClassLoaderData in the graph since the CLD 704 // contains unhandled oops 705 706 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies); 707 708 709 if (!is_anonymous) { 710 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader()); 711 // First, Atomically set it 712 ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL); 713 if (old != NULL) { 714 delete cld; 715 // Returns the data. 716 return old; 717 } 718 } 719 720 // We won the race, and therefore the task of adding the data to the list of 721 // class loader data 722 ClassLoaderData** list_head = &_head; 723 ClassLoaderData* next = _head; 724 725 do { 726 cld->set_next(next); 727 ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next); 728 if (exchanged == next) { 729 if (log_is_enabled(Debug, class, loader, data)) { 730 PauseNoSafepointVerifier pnsv(&no_safepoints); // Need safe points for JavaCalls::call_virtual 731 log_creation(loader, cld, CHECK_NULL); 732 } 733 return cld; 734 } 735 next = exchanged; 736 } while (true); 737 } 738 739 void ClassLoaderDataGraph::log_creation(Handle loader, ClassLoaderData* cld, TRAPS) { 740 Handle string; 741 if (loader.not_null()) { 742 // Include the result of loader.toString() in the output. This allows 743 // the user of the log to identify the class loader instance. 744 JavaValue result(T_OBJECT); 745 KlassHandle spec_klass(THREAD, SystemDictionary::ClassLoader_klass()); 746 JavaCalls::call_virtual(&result, 747 loader, 748 spec_klass, 749 vmSymbols::toString_name(), 750 vmSymbols::void_string_signature(), 751 CHECK); 752 assert(result.get_type() == T_OBJECT, "just checking"); 753 string = (oop)result.get_jobject(); 754 } 755 756 ResourceMark rm; 757 outputStream* log = Log(class, loader, data)::debug_stream(); 758 log->print("create class loader data " INTPTR_FORMAT, p2i(cld)); 759 log->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()), 760 cld->loader_name()); 761 762 if (string.not_null()) { 763 log->print(": "); 764 java_lang_String::print(string(), log); 765 } 766 log->cr(); 767 } 768 769 770 void ClassLoaderDataGraph::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 771 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 772 cld->oops_do(f, klass_closure, must_claim); 773 } 774 } 775 776 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 777 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 778 if (cld->keep_alive()) { 779 cld->oops_do(f, klass_closure, must_claim); 780 } 781 } 782 } 783 784 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 785 if (ClassUnloading) { 786 keep_alive_oops_do(f, klass_closure, must_claim); 787 } else { 788 oops_do(f, klass_closure, must_claim); 789 } 790 } 791 792 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) { 793 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) { 794 cl->do_cld(cld); 795 } 796 } 797 798 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) { 799 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) { 800 CLDClosure* closure = cld->keep_alive() ? strong : weak; 801 if (closure != NULL) { 802 closure->do_cld(cld); 803 } 804 } 805 } 806 807 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) { 808 roots_cld_do(cl, NULL); 809 } 810 811 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) { 812 if (ClassUnloading) { 813 keep_alive_cld_do(cl); 814 } else { 815 cld_do(cl); 816 } 817 } 818 819 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) { 820 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 821 cld->classes_do(klass_closure); 822 } 823 } 824 825 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) { 826 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 827 cld->classes_do(f); 828 } 829 } 830 831 void ClassLoaderDataGraph::methods_do(void f(Method*)) { 832 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 833 cld->methods_do(f); 834 } 835 } 836 837 void ClassLoaderDataGraph::modules_do(void f(ModuleEntry*)) { 838 assert_locked_or_safepoint(Module_lock); 839 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 840 cld->modules_do(f); 841 } 842 } 843 844 void ClassLoaderDataGraph::modules_unloading_do(void f(ModuleEntry*)) { 845 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 846 // Only walk the head until any clds not purged from prior unloading 847 // (CMS doesn't purge right away). 848 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) { 849 assert(cld->is_unloading(), "invariant"); 850 cld->modules_do(f); 851 } 852 } 853 854 void ClassLoaderDataGraph::packages_do(void f(PackageEntry*)) { 855 assert_locked_or_safepoint(Module_lock); 856 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 857 cld->packages_do(f); 858 } 859 } 860 861 void ClassLoaderDataGraph::packages_unloading_do(void f(PackageEntry*)) { 862 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 863 // Only walk the head until any clds not purged from prior unloading 864 // (CMS doesn't purge right away). 865 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) { 866 assert(cld->is_unloading(), "invariant"); 867 cld->packages_do(f); 868 } 869 } 870 871 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) { 872 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 873 cld->loaded_classes_do(klass_closure); 874 } 875 } 876 877 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) { 878 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 879 // Only walk the head until any clds not purged from prior unloading 880 // (CMS doesn't purge right away). 881 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) { 882 assert(cld->is_unloading(), "invariant"); 883 cld->classes_do(f); 884 } 885 } 886 887 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() { 888 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?"); 889 890 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>(); 891 892 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true); 893 ClassLoaderData* curr = _head; 894 while (curr != _saved_head) { 895 if (!curr->claimed()) { 896 array->push(curr); 897 898 if (log_is_enabled(Debug, class, loader, data)) { 899 outputStream* log = Log(class, loader, data)::debug_stream(); 900 log->print("found new CLD: "); 901 curr->print_value_on(log); 902 log->cr(); 903 } 904 } 905 906 curr = curr->_next; 907 } 908 909 return array; 910 } 911 912 bool ClassLoaderDataGraph::unload_list_contains(const void* x) { 913 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint"); 914 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) { 915 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) { 916 return true; 917 } 918 } 919 return false; 920 } 921 922 #ifndef PRODUCT 923 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) { 924 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 925 if (loader_data == data) { 926 return true; 927 } 928 } 929 930 return false; 931 } 932 #endif // PRODUCT 933 934 935 // Move class loader data from main list to the unloaded list for unloading 936 // and deallocation later. 937 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure, 938 bool clean_previous_versions) { 939 940 ClassLoaderData* data = _head; 941 ClassLoaderData* prev = NULL; 942 bool seen_dead_loader = false; 943 944 // Mark metadata seen on the stack only so we can delete unneeded entries. 945 // Only walk all metadata, including the expensive code cache walk, for Full GC 946 // and only if class redefinition and if there's previous versions of 947 // Klasses to delete. 948 bool walk_all_metadata = clean_previous_versions && 949 JvmtiExport::has_redefined_a_class() && 950 InstanceKlass::has_previous_versions(); 951 MetadataOnStackMark md_on_stack(walk_all_metadata); 952 953 // Save previous _unloading pointer for CMS which may add to unloading list before 954 // purging and we don't want to rewalk the previously unloaded class loader data. 955 _saved_unloading = _unloading; 956 957 data = _head; 958 while (data != NULL) { 959 if (data->is_alive(is_alive_closure)) { 960 if (data->packages_defined()) { 961 data->packages()->purge_all_package_exports(); 962 } 963 if (data->modules_defined()) { 964 data->modules()->purge_all_module_reads(); 965 } 966 // clean metaspace 967 if (walk_all_metadata) { 968 data->classes_do(InstanceKlass::purge_previous_versions); 969 } 970 data->free_deallocate_list(); 971 prev = data; 972 data = data->next(); 973 continue; 974 } 975 seen_dead_loader = true; 976 ClassLoaderData* dead = data; 977 dead->unload(); 978 data = data->next(); 979 // Remove from loader list. 980 // This class loader data will no longer be found 981 // in the ClassLoaderDataGraph. 982 if (prev != NULL) { 983 prev->set_next(data); 984 } else { 985 assert(dead == _head, "sanity check"); 986 _head = data; 987 } 988 dead->set_next(_unloading); 989 _unloading = dead; 990 } 991 992 if (seen_dead_loader) { 993 post_class_unload_events(); 994 } 995 996 return seen_dead_loader; 997 } 998 999 void ClassLoaderDataGraph::purge() { 1000 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 1001 ClassLoaderData* list = _unloading; 1002 _unloading = NULL; 1003 ClassLoaderData* next = list; 1004 bool classes_unloaded = false; 1005 while (next != NULL) { 1006 ClassLoaderData* purge_me = next; 1007 next = purge_me->next(); 1008 delete purge_me; 1009 classes_unloaded = true; 1010 } 1011 if (classes_unloaded) { 1012 Metaspace::purge(); 1013 set_metaspace_oom(false); 1014 } 1015 } 1016 1017 void ClassLoaderDataGraph::post_class_unload_events(void) { 1018 #if INCLUDE_TRACE 1019 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 1020 if (Tracing::enabled()) { 1021 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) { 1022 assert(_unloading != NULL, "need class loader data unload list!"); 1023 _class_unload_time = Ticks::now(); 1024 classes_unloading_do(&class_unload_event); 1025 } 1026 Tracing::on_unloading_classes(); 1027 } 1028 #endif 1029 } 1030 1031 // CDS support 1032 1033 // Global metaspaces for writing information to the shared archive. When 1034 // application CDS is supported, we may need one per metaspace, so this 1035 // sort of looks like it. 1036 Metaspace* ClassLoaderData::_ro_metaspace = NULL; 1037 Metaspace* ClassLoaderData::_rw_metaspace = NULL; 1038 static bool _shared_metaspaces_initialized = false; 1039 1040 // Initialize shared metaspaces (change to call from somewhere not lazily) 1041 void ClassLoaderData::initialize_shared_metaspaces() { 1042 assert(DumpSharedSpaces, "only use this for dumping shared spaces"); 1043 assert(this == ClassLoaderData::the_null_class_loader_data(), 1044 "only supported for null loader data for now"); 1045 assert (!_shared_metaspaces_initialized, "only initialize once"); 1046 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 1047 _ro_metaspace = new Metaspace(_metaspace_lock, Metaspace::ROMetaspaceType); 1048 _rw_metaspace = new Metaspace(_metaspace_lock, Metaspace::ReadWriteMetaspaceType); 1049 _shared_metaspaces_initialized = true; 1050 } 1051 1052 Metaspace* ClassLoaderData::ro_metaspace() { 1053 assert(_ro_metaspace != NULL, "should already be initialized"); 1054 return _ro_metaspace; 1055 } 1056 1057 Metaspace* ClassLoaderData::rw_metaspace() { 1058 assert(_rw_metaspace != NULL, "should already be initialized"); 1059 return _rw_metaspace; 1060 } 1061 1062 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic() 1063 : _next_klass(NULL) { 1064 ClassLoaderData* cld = ClassLoaderDataGraph::_head; 1065 Klass* klass = NULL; 1066 1067 // Find the first klass in the CLDG. 1068 while (cld != NULL) { 1069 assert_locked_or_safepoint(cld->metaspace_lock()); 1070 klass = cld->_klasses; 1071 if (klass != NULL) { 1072 _next_klass = klass; 1073 return; 1074 } 1075 cld = cld->next(); 1076 } 1077 } 1078 1079 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) { 1080 Klass* next = klass->next_link(); 1081 if (next != NULL) { 1082 return next; 1083 } 1084 1085 // No more klasses in the current CLD. Time to find a new CLD. 1086 ClassLoaderData* cld = klass->class_loader_data(); 1087 assert_locked_or_safepoint(cld->metaspace_lock()); 1088 while (next == NULL) { 1089 cld = cld->next(); 1090 if (cld == NULL) { 1091 break; 1092 } 1093 next = cld->_klasses; 1094 } 1095 1096 return next; 1097 } 1098 1099 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() { 1100 Klass* head = _next_klass; 1101 1102 while (head != NULL) { 1103 Klass* next = next_klass_in_cldg(head); 1104 1105 Klass* old_head = (Klass*)Atomic::cmpxchg_ptr(next, &_next_klass, head); 1106 1107 if (old_head == head) { 1108 return head; // Won the CAS. 1109 } 1110 1111 head = old_head; 1112 } 1113 1114 // Nothing more for the iterator to hand out. 1115 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head)); 1116 return NULL; 1117 } 1118 1119 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() { 1120 _data = ClassLoaderDataGraph::_head; 1121 } 1122 1123 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {} 1124 1125 #ifndef PRODUCT 1126 // callable from debugger 1127 extern "C" int print_loader_data_graph() { 1128 ClassLoaderDataGraph::dump_on(tty); 1129 return 0; 1130 } 1131 1132 void ClassLoaderDataGraph::verify() { 1133 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 1134 data->verify(); 1135 } 1136 } 1137 1138 void ClassLoaderDataGraph::dump_on(outputStream * const out) { 1139 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 1140 data->dump(out); 1141 } 1142 MetaspaceAux::dump(out); 1143 } 1144 #endif // PRODUCT 1145 1146 void ClassLoaderData::print_value_on(outputStream* out) const { 1147 if (class_loader() == NULL) { 1148 out->print("NULL class_loader"); 1149 } else { 1150 out->print("class loader " INTPTR_FORMAT, p2i(this)); 1151 class_loader()->print_value_on(out); 1152 } 1153 } 1154 1155 #if INCLUDE_TRACE 1156 1157 Ticks ClassLoaderDataGraph::_class_unload_time; 1158 1159 void ClassLoaderDataGraph::class_unload_event(Klass* const k) { 1160 assert(k != NULL, "invariant"); 1161 1162 // post class unload event 1163 EventClassUnload event(UNTIMED); 1164 event.set_endtime(_class_unload_time); 1165 event.set_unloadedClass(k); 1166 oop defining_class_loader = k->class_loader(); 1167 event.set_definingClassLoader(defining_class_loader != NULL ? 1168 defining_class_loader->klass() : (Klass*)NULL); 1169 event.commit(); 1170 } 1171 1172 #endif // INCLUDE_TRACE