classLoaderData.cpp revision 11857:d0fbf661cc16
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.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 81template <typename T> static T* load_ptr_acquire(T* volatile *p) { 82 return static_cast<T*>(OrderAccess::load_ptr_acquire(p)); 83} 84 85ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL; 86 87ClassLoaderData::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 103void 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 109void 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 115bool 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. 128void ClassLoaderData::inc_keep_alive() { 129 if (is_anonymous()) { 130 assert(_keep_alive >= 0, "Invalid keep alive increment count"); 131 _keep_alive++; 132 } 133} 134 135void ClassLoaderData::dec_keep_alive() { 136 if (is_anonymous()) { 137 assert(_keep_alive > 0, "Invalid keep alive decrement count"); 138 _keep_alive--; 139 } 140} 141 142void ClassLoaderData::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 143 if (must_claim && !claim()) { 144 return; 145 } 146 147 f->do_oop(&_class_loader); 148 _dependencies.oops_do(f); 149 if (_handles != NULL) { 150 _handles->oops_do(f); 151 } 152 if (klass_closure != NULL) { 153 classes_do(klass_closure); 154 } 155} 156 157void ClassLoaderData::Dependencies::oops_do(OopClosure* f) { 158 f->do_oop((oop*)&_list_head); 159} 160 161void ClassLoaderData::classes_do(KlassClosure* klass_closure) { 162 // Lock-free access requires load_ptr_acquire 163 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) { 164 klass_closure->do_klass(k); 165 assert(k != k->next_link(), "no loops!"); 166 } 167} 168 169void ClassLoaderData::classes_do(void f(Klass * const)) { 170 assert_locked_or_safepoint(_metaspace_lock); 171 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 172 f(k); 173 } 174} 175 176void ClassLoaderData::methods_do(void f(Method*)) { 177 // Lock-free access requires load_ptr_acquire 178 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) { 179 if (k->is_instance_klass()) { 180 InstanceKlass::cast(k)->methods_do(f); 181 } 182 } 183} 184 185void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) { 186 // Lock to avoid classes being modified/added/removed during iteration 187 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 188 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 189 // Do not filter ArrayKlass oops here... 190 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) { 191 klass_closure->do_klass(k); 192 } 193 } 194} 195 196void ClassLoaderData::classes_do(void f(InstanceKlass*)) { 197 // Lock-free access requires load_ptr_acquire 198 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) { 199 if (k->is_instance_klass()) { 200 f(InstanceKlass::cast(k)); 201 } 202 assert(k != k->next_link(), "no loops!"); 203 } 204} 205 206void ClassLoaderData::modules_do(void f(ModuleEntry*)) { 207 assert_locked_or_safepoint(Module_lock); 208 if (_modules != NULL) { 209 for (int i = 0; i < _modules->table_size(); i++) { 210 for (ModuleEntry* entry = _modules->bucket(i); 211 entry != NULL; 212 entry = entry->next()) { 213 f(entry); 214 } 215 } 216 } 217} 218 219void ClassLoaderData::packages_do(void f(PackageEntry*)) { 220 // Lock-free access requires load_ptr_acquire 221 PackageEntryTable* packages = load_ptr_acquire(&_packages); 222 if (packages != NULL) { 223 for (int i = 0; i < packages->table_size(); i++) { 224 for (PackageEntry* entry = packages->bucket(i); 225 entry != NULL; 226 entry = entry->next()) { 227 f(entry); 228 } 229 } 230 } 231} 232 233void ClassLoaderData::record_dependency(const Klass* k, TRAPS) { 234 assert(k != NULL, "invariant"); 235 236 ClassLoaderData * const from_cld = this; 237 ClassLoaderData * const to_cld = k->class_loader_data(); 238 239 // Dependency to the null class loader data doesn't need to be recorded 240 // because the null class loader data never goes away. 241 if (to_cld->is_the_null_class_loader_data()) { 242 return; 243 } 244 245 oop to; 246 if (to_cld->is_anonymous()) { 247 // Anonymous class dependencies are through the mirror. 248 to = k->java_mirror(); 249 } else { 250 to = to_cld->class_loader(); 251 252 // If from_cld is anonymous, even if it's class_loader is a parent of 'to' 253 // we still have to add it. The class_loader won't keep from_cld alive. 254 if (!from_cld->is_anonymous()) { 255 // Check that this dependency isn't from the same or parent class_loader 256 oop from = from_cld->class_loader(); 257 258 oop curr = from; 259 while (curr != NULL) { 260 if (curr == to) { 261 return; // this class loader is in the parent list, no need to add it. 262 } 263 curr = java_lang_ClassLoader::parent(curr); 264 } 265 } 266 } 267 268 // It's a dependency we won't find through GC, add it. This is relatively rare 269 // Must handle over GC point. 270 Handle dependency(THREAD, to); 271 from_cld->_dependencies.add(dependency, CHECK); 272} 273 274 275void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) { 276 // Check first if this dependency is already in the list. 277 // Save a pointer to the last to add to under the lock. 278 objArrayOop ok = _list_head; 279 objArrayOop last = NULL; 280 while (ok != NULL) { 281 last = ok; 282 if (ok->obj_at(0) == dependency()) { 283 // Don't need to add it 284 return; 285 } 286 ok = (objArrayOop)ok->obj_at(1); 287 } 288 289 // Must handle over GC points 290 assert (last != NULL, "dependencies should be initialized"); 291 objArrayHandle last_handle(THREAD, last); 292 293 // Create a new dependency node with fields for (class_loader or mirror, next) 294 objArrayOop deps = oopFactory::new_objectArray(2, CHECK); 295 deps->obj_at_put(0, dependency()); 296 297 // Must handle over GC points 298 objArrayHandle new_dependency(THREAD, deps); 299 300 // Add the dependency under lock 301 locked_add(last_handle, new_dependency, THREAD); 302} 303 304void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle, 305 objArrayHandle new_dependency, 306 Thread* THREAD) { 307 308 // Have to lock and put the new dependency on the end of the dependency 309 // array so the card mark for CMS sees that this dependency is new. 310 // Can probably do this lock free with some effort. 311 ObjectLocker ol(Handle(THREAD, _list_head), THREAD); 312 313 oop loader_or_mirror = new_dependency->obj_at(0); 314 315 // Since the dependencies are only added, add to the end. 316 objArrayOop end = last_handle(); 317 objArrayOop last = NULL; 318 while (end != NULL) { 319 last = end; 320 // check again if another thread added it to the end. 321 if (end->obj_at(0) == loader_or_mirror) { 322 // Don't need to add it 323 return; 324 } 325 end = (objArrayOop)end->obj_at(1); 326 } 327 assert (last != NULL, "dependencies should be initialized"); 328 // fill in the first element with the oop in new_dependency. 329 if (last->obj_at(0) == NULL) { 330 last->obj_at_put(0, new_dependency->obj_at(0)); 331 } else { 332 last->obj_at_put(1, new_dependency()); 333 } 334} 335 336void ClassLoaderDataGraph::clear_claimed_marks() { 337 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 338 cld->clear_claimed(); 339 } 340} 341 342void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) { 343 { 344 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 345 Klass* old_value = _klasses; 346 k->set_next_link(old_value); 347 // Link the new item into the list, making sure the linked class is stable 348 // since the list can be walked without a lock 349 OrderAccess::release_store_ptr(&_klasses, k); 350 } 351 352 if (publicize && k->class_loader_data() != NULL) { 353 ResourceMark rm; 354 log_trace(class, loader, data)("Adding k: " PTR_FORMAT " %s to CLD: " 355 PTR_FORMAT " loader: " PTR_FORMAT " %s", 356 p2i(k), 357 k->external_name(), 358 p2i(k->class_loader_data()), 359 p2i((void *)k->class_loader()), 360 loader_name()); 361 } 362} 363 364// Remove a klass from the _klasses list for scratch_class during redefinition 365// or parsed class in the case of an error. 366void ClassLoaderData::remove_class(Klass* scratch_class) { 367 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 368 Klass* prev = NULL; 369 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 370 if (k == scratch_class) { 371 if (prev == NULL) { 372 _klasses = k->next_link(); 373 } else { 374 Klass* next = k->next_link(); 375 prev->set_next_link(next); 376 } 377 return; 378 } 379 prev = k; 380 assert(k != k->next_link(), "no loops!"); 381 } 382 ShouldNotReachHere(); // should have found this class!! 383} 384 385void ClassLoaderData::unload() { 386 _unloading = true; 387 388 // Tell serviceability tools these classes are unloading 389 classes_do(InstanceKlass::notify_unload_class); 390 391 if (log_is_enabled(Debug, class, loader, data)) { 392 ResourceMark rm; 393 outputStream* log = Log(class, loader, data)::debug_stream(); 394 log->print(": unload loader data " INTPTR_FORMAT, p2i(this)); 395 log->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()), 396 loader_name()); 397 if (is_anonymous()) { 398 log->print(" for anonymous class " INTPTR_FORMAT " ", p2i(_klasses)); 399 } 400 log->cr(); 401 } 402 403 // In some rare cases items added to this list will not be freed elsewhere. 404 // To keep it simple, just free everything in it here. 405 free_deallocate_list(); 406} 407 408PackageEntryTable* ClassLoaderData::packages() { 409 // Lazily create the package entry table at first request. 410 // Lock-free access requires load_ptr_acquire. 411 PackageEntryTable* packages = load_ptr_acquire(&_packages); 412 if (packages == NULL) { 413 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag); 414 // Check if _packages got allocated while we were waiting for this lock. 415 if ((packages = _packages) == NULL) { 416 packages = new PackageEntryTable(PackageEntryTable::_packagetable_entry_size); 417 // Ensure _packages is stable, since it is examined without a lock 418 OrderAccess::release_store_ptr(&_packages, packages); 419 } 420 } 421 return packages; 422} 423 424ModuleEntryTable* ClassLoaderData::modules() { 425 // Lazily create the module entry table at first request. 426 // Lock-free access requires load_ptr_acquire. 427 ModuleEntryTable* modules = load_ptr_acquire(&_modules); 428 if (modules == NULL) { 429 MutexLocker m1(Module_lock); 430 // Check if _modules got allocated while we were waiting for this lock. 431 if ((modules = _modules) == NULL) { 432 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size); 433 // Each loader has one unnamed module entry. Create it before 434 // any classes, loaded by this loader, are defined in case 435 // they end up being defined in loader's unnamed module. 436 modules->create_unnamed_module(this); 437 438 { 439 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag); 440 // Ensure _modules is stable, since it is examined without a lock 441 OrderAccess::release_store_ptr(&_modules, modules); 442 } 443 } 444 } 445 return modules; 446} 447 448oop ClassLoaderData::keep_alive_object() const { 449 assert_locked_or_safepoint(_metaspace_lock); 450 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive"); 451 return is_anonymous() ? _klasses->java_mirror() : class_loader(); 452} 453 454bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const { 455 bool alive = keep_alive() // null class loader and incomplete anonymous klasses. 456 || is_alive_closure->do_object_b(keep_alive_object()); 457 458 return alive; 459} 460 461 462ClassLoaderData::~ClassLoaderData() { 463 // Release C heap structures for all the classes. 464 classes_do(InstanceKlass::release_C_heap_structures); 465 466 // Release C heap allocated hashtable for all the packages. 467 if (_packages != NULL) { 468 // Destroy the table itself 469 delete _packages; 470 _packages = NULL; 471 } 472 473 // Release C heap allocated hashtable for all the modules. 474 if (_modules != NULL) { 475 // Destroy the table itself 476 delete _modules; 477 _modules = NULL; 478 } 479 480 // release the metaspace 481 Metaspace *m = _metaspace; 482 if (m != NULL) { 483 _metaspace = NULL; 484 delete m; 485 } 486 // release the handles 487 if (_handles != NULL) { 488 JNIHandleBlock::release_block(_handles); 489 _handles = NULL; 490 } 491 492 // Clear all the JNI handles for methods 493 // These aren't deallocated and are going to look like a leak, but that's 494 // needed because we can't really get rid of jmethodIDs because we don't 495 // know when native code is going to stop using them. The spec says that 496 // they're "invalid" but existing programs likely rely on their being 497 // NULL after class unloading. 498 if (_jmethod_ids != NULL) { 499 Method::clear_jmethod_ids(this); 500 } 501 // Delete lock 502 delete _metaspace_lock; 503 504 // Delete free list 505 if (_deallocate_list != NULL) { 506 delete _deallocate_list; 507 } 508} 509 510// Returns true if this class loader data is for the system class loader. 511bool ClassLoaderData::is_system_class_loader_data() const { 512 return SystemDictionary::is_system_class_loader(class_loader()); 513} 514 515// Returns true if this class loader data is for the platform class loader. 516bool ClassLoaderData::is_platform_class_loader_data() const { 517 return SystemDictionary::is_platform_class_loader(class_loader()); 518} 519 520// Returns true if this class loader data is one of the 3 builtin 521// (boot, application/system or platform) class loaders. Note, the 522// builtin loaders are not freed by a GC. 523bool ClassLoaderData::is_builtin_class_loader_data() const { 524 Handle classLoaderHandle = class_loader(); 525 return (is_the_null_class_loader_data() || 526 SystemDictionary::is_system_class_loader(classLoaderHandle) || 527 SystemDictionary::is_platform_class_loader(classLoaderHandle)); 528} 529 530Metaspace* ClassLoaderData::metaspace_non_null() { 531 assert(!DumpSharedSpaces, "wrong metaspace!"); 532 // If the metaspace has not been allocated, create a new one. Might want 533 // to create smaller arena for Reflection class loaders also. 534 // The reason for the delayed allocation is because some class loaders are 535 // simply for delegating with no metadata of their own. 536 // Lock-free access requires load_ptr_acquire. 537 Metaspace* metaspace = load_ptr_acquire(&_metaspace); 538 if (metaspace == NULL) { 539 MutexLockerEx ml(_metaspace_lock, Mutex::_no_safepoint_check_flag); 540 // Check if _metaspace got allocated while we were waiting for this lock. 541 if ((metaspace = _metaspace) == NULL) { 542 if (this == the_null_class_loader_data()) { 543 assert (class_loader() == NULL, "Must be"); 544 metaspace = new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType); 545 } else if (is_anonymous()) { 546 if (class_loader() != NULL) { 547 log_trace(class, loader, data)("is_anonymous: %s", class_loader()->klass()->internal_name()); 548 } 549 metaspace = new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType); 550 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) { 551 if (class_loader() != NULL) { 552 log_trace(class, loader, data)("is_reflection: %s", class_loader()->klass()->internal_name()); 553 } 554 metaspace = new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType); 555 } else { 556 metaspace = new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType); 557 } 558 // Ensure _metaspace is stable, since it is examined without a lock 559 OrderAccess::release_store_ptr(&_metaspace, metaspace); 560 } 561 } 562 return metaspace; 563} 564 565JNIHandleBlock* ClassLoaderData::handles() const { return _handles; } 566void ClassLoaderData::set_handles(JNIHandleBlock* handles) { _handles = handles; } 567 568jobject ClassLoaderData::add_handle(Handle h) { 569 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 570 if (handles() == NULL) { 571 set_handles(JNIHandleBlock::allocate_block()); 572 } 573 return handles()->allocate_handle(h()); 574} 575 576void ClassLoaderData::remove_handle(jobject h) { 577 _handles->release_handle(h); 578} 579 580// Add this metadata pointer to be freed when it's safe. This is only during 581// class unloading because Handles might point to this metadata field. 582void ClassLoaderData::add_to_deallocate_list(Metadata* m) { 583 // Metadata in shared region isn't deleted. 584 if (!m->is_shared()) { 585 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 586 if (_deallocate_list == NULL) { 587 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true); 588 } 589 _deallocate_list->append_if_missing(m); 590 } 591} 592 593// Deallocate free metadata on the free list. How useful the PermGen was! 594void ClassLoaderData::free_deallocate_list() { 595 // Don't need lock, at safepoint 596 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 597 if (_deallocate_list == NULL) { 598 return; 599 } 600 // Go backwards because this removes entries that are freed. 601 for (int i = _deallocate_list->length() - 1; i >= 0; i--) { 602 Metadata* m = _deallocate_list->at(i); 603 if (!m->on_stack()) { 604 _deallocate_list->remove_at(i); 605 // There are only three types of metadata that we deallocate directly. 606 // Cast them so they can be used by the template function. 607 if (m->is_method()) { 608 MetadataFactory::free_metadata(this, (Method*)m); 609 } else if (m->is_constantPool()) { 610 MetadataFactory::free_metadata(this, (ConstantPool*)m); 611 } else if (m->is_klass()) { 612 MetadataFactory::free_metadata(this, (InstanceKlass*)m); 613 } else { 614 ShouldNotReachHere(); 615 } 616 } else { 617 // Metadata is alive. 618 // If scratch_class is on stack then it shouldn't be on this list! 619 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(), 620 "scratch classes on this list should be dead"); 621 // Also should assert that other metadata on the list was found in handles. 622 } 623 } 624} 625 626// These anonymous class loaders are to contain classes used for JSR292 627ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) { 628 // Add a new class loader data to the graph. 629 return ClassLoaderDataGraph::add(loader, true, THREAD); 630} 631 632const char* ClassLoaderData::loader_name() { 633 // Handles null class loader 634 return SystemDictionary::loader_name(class_loader()); 635} 636 637#ifndef PRODUCT 638// Define to dump klasses 639#undef CLD_DUMP_KLASSES 640 641void ClassLoaderData::dump(outputStream * const out) { 642 ResourceMark rm; 643 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: " PTR_FORMAT " %s {", 644 p2i(this), p2i((void *)class_loader()), 645 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name()); 646 if (claimed()) out->print(" claimed "); 647 if (is_unloading()) out->print(" unloading "); 648 out->print(" handles " INTPTR_FORMAT, p2i(handles())); 649 out->cr(); 650 if (metaspace_or_null() != NULL) { 651 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null())); 652 metaspace_or_null()->dump(out); 653 } else { 654 out->print_cr("metaspace: NULL"); 655 } 656 657#ifdef CLD_DUMP_KLASSES 658 if (Verbose) { 659 ResourceMark rm; 660 Klass* k = _klasses; 661 while (k != NULL) { 662 out->print_cr("klass " PTR_FORMAT ", %s, CT: %d, MUT: %d", k, k->name()->as_C_string(), 663 k->has_modified_oops(), k->has_accumulated_modified_oops()); 664 assert(k != k->next_link(), "no loops!"); 665 k = k->next_link(); 666 } 667 } 668#endif // CLD_DUMP_KLASSES 669#undef CLD_DUMP_KLASSES 670 if (_jmethod_ids != NULL) { 671 Method::print_jmethod_ids(this, out); 672 } 673 out->print_cr("}"); 674} 675#endif // PRODUCT 676 677void ClassLoaderData::verify() { 678 assert_locked_or_safepoint(_metaspace_lock); 679 oop cl = class_loader(); 680 681 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same"); 682 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be"); 683 684 // Verify the integrity of the allocated space. 685 if (metaspace_or_null() != NULL) { 686 metaspace_or_null()->verify(); 687 } 688 689 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 690 guarantee(k->class_loader_data() == this, "Must be the same"); 691 k->verify(); 692 assert(k != k->next_link(), "no loops!"); 693 } 694} 695 696bool ClassLoaderData::contains_klass(Klass* klass) { 697 // Lock-free access requires load_ptr_acquire 698 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) { 699 if (k == klass) return true; 700 } 701 return false; 702} 703 704 705// GC root of class loader data created. 706ClassLoaderData* ClassLoaderDataGraph::_head = NULL; 707ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL; 708ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL; 709ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL; 710 711bool ClassLoaderDataGraph::_should_purge = false; 712bool ClassLoaderDataGraph::_metaspace_oom = false; 713 714// Add a new class loader data node to the list. Assign the newly created 715// ClassLoaderData into the java/lang/ClassLoader object as a hidden field 716ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) { 717 // We need to allocate all the oops for the ClassLoaderData before allocating the 718 // actual ClassLoaderData object. 719 ClassLoaderData::Dependencies dependencies(CHECK_NULL); 720 721 NoSafepointVerifier no_safepoints; // we mustn't GC until we've installed the 722 // ClassLoaderData in the graph since the CLD 723 // contains unhandled oops 724 725 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies); 726 727 728 if (!is_anonymous) { 729 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader()); 730 // First, Atomically set it 731 ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL); 732 if (old != NULL) { 733 delete cld; 734 // Returns the data. 735 return old; 736 } 737 } 738 739 // We won the race, and therefore the task of adding the data to the list of 740 // class loader data 741 ClassLoaderData** list_head = &_head; 742 ClassLoaderData* next = _head; 743 744 do { 745 cld->set_next(next); 746 ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next); 747 if (exchanged == next) { 748 if (log_is_enabled(Debug, class, loader, data)) { 749 PauseNoSafepointVerifier pnsv(&no_safepoints); // Need safe points for JavaCalls::call_virtual 750 log_creation(loader, cld, CHECK_NULL); 751 } 752 return cld; 753 } 754 next = exchanged; 755 } while (true); 756} 757 758void ClassLoaderDataGraph::log_creation(Handle loader, ClassLoaderData* cld, TRAPS) { 759 Handle string; 760 if (loader.not_null()) { 761 // Include the result of loader.toString() in the output. This allows 762 // the user of the log to identify the class loader instance. 763 JavaValue result(T_OBJECT); 764 KlassHandle spec_klass(THREAD, SystemDictionary::ClassLoader_klass()); 765 JavaCalls::call_virtual(&result, 766 loader, 767 spec_klass, 768 vmSymbols::toString_name(), 769 vmSymbols::void_string_signature(), 770 CHECK); 771 assert(result.get_type() == T_OBJECT, "just checking"); 772 string = (oop)result.get_jobject(); 773 } 774 775 ResourceMark rm; 776 outputStream* log = Log(class, loader, data)::debug_stream(); 777 log->print("create class loader data " INTPTR_FORMAT, p2i(cld)); 778 log->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()), 779 cld->loader_name()); 780 781 if (string.not_null()) { 782 log->print(": "); 783 java_lang_String::print(string(), log); 784 } 785 log->cr(); 786} 787 788 789void ClassLoaderDataGraph::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 790 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 791 cld->oops_do(f, klass_closure, must_claim); 792 } 793} 794 795void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 796 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 797 if (cld->keep_alive()) { 798 cld->oops_do(f, klass_closure, must_claim); 799 } 800 } 801} 802 803void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 804 if (ClassUnloading) { 805 keep_alive_oops_do(f, klass_closure, must_claim); 806 } else { 807 oops_do(f, klass_closure, must_claim); 808 } 809} 810 811void ClassLoaderDataGraph::cld_do(CLDClosure* cl) { 812 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) { 813 cl->do_cld(cld); 814 } 815} 816 817void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) { 818 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) { 819 CLDClosure* closure = cld->keep_alive() ? strong : weak; 820 if (closure != NULL) { 821 closure->do_cld(cld); 822 } 823 } 824} 825 826void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) { 827 roots_cld_do(cl, NULL); 828} 829 830void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) { 831 if (ClassUnloading) { 832 keep_alive_cld_do(cl); 833 } else { 834 cld_do(cl); 835 } 836} 837 838void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) { 839 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 840 cld->classes_do(klass_closure); 841 } 842} 843 844void ClassLoaderDataGraph::classes_do(void f(Klass* const)) { 845 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 846 cld->classes_do(f); 847 } 848} 849 850void ClassLoaderDataGraph::methods_do(void f(Method*)) { 851 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 852 cld->methods_do(f); 853 } 854} 855 856void ClassLoaderDataGraph::modules_do(void f(ModuleEntry*)) { 857 assert_locked_or_safepoint(Module_lock); 858 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 859 cld->modules_do(f); 860 } 861} 862 863void ClassLoaderDataGraph::modules_unloading_do(void f(ModuleEntry*)) { 864 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 865 // Only walk the head until any clds not purged from prior unloading 866 // (CMS doesn't purge right away). 867 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) { 868 assert(cld->is_unloading(), "invariant"); 869 cld->modules_do(f); 870 } 871} 872 873void ClassLoaderDataGraph::packages_do(void f(PackageEntry*)) { 874 assert_locked_or_safepoint(Module_lock); 875 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 876 cld->packages_do(f); 877 } 878} 879 880void ClassLoaderDataGraph::packages_unloading_do(void f(PackageEntry*)) { 881 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 882 // Only walk the head until any clds not purged from prior unloading 883 // (CMS doesn't purge right away). 884 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) { 885 assert(cld->is_unloading(), "invariant"); 886 cld->packages_do(f); 887 } 888} 889 890void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) { 891 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 892 cld->loaded_classes_do(klass_closure); 893 } 894} 895 896void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) { 897 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 898 // Only walk the head until any clds not purged from prior unloading 899 // (CMS doesn't purge right away). 900 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) { 901 assert(cld->is_unloading(), "invariant"); 902 cld->classes_do(f); 903 } 904} 905 906GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() { 907 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?"); 908 909 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>(); 910 911 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true); 912 ClassLoaderData* curr = _head; 913 while (curr != _saved_head) { 914 if (!curr->claimed()) { 915 array->push(curr); 916 917 if (log_is_enabled(Debug, class, loader, data)) { 918 outputStream* log = Log(class, loader, data)::debug_stream(); 919 log->print("found new CLD: "); 920 curr->print_value_on(log); 921 log->cr(); 922 } 923 } 924 925 curr = curr->_next; 926 } 927 928 return array; 929} 930 931bool ClassLoaderDataGraph::unload_list_contains(const void* x) { 932 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint"); 933 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) { 934 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) { 935 return true; 936 } 937 } 938 return false; 939} 940 941#ifndef PRODUCT 942bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) { 943 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 944 if (loader_data == data) { 945 return true; 946 } 947 } 948 949 return false; 950} 951#endif // PRODUCT 952 953 954// Move class loader data from main list to the unloaded list for unloading 955// and deallocation later. 956bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure, 957 bool clean_previous_versions) { 958 959 ClassLoaderData* data = _head; 960 ClassLoaderData* prev = NULL; 961 bool seen_dead_loader = false; 962 963 // Mark metadata seen on the stack only so we can delete unneeded entries. 964 // Only walk all metadata, including the expensive code cache walk, for Full GC 965 // and only if class redefinition and if there's previous versions of 966 // Klasses to delete. 967 bool walk_all_metadata = clean_previous_versions && 968 JvmtiExport::has_redefined_a_class() && 969 InstanceKlass::has_previous_versions(); 970 MetadataOnStackMark md_on_stack(walk_all_metadata); 971 972 // Save previous _unloading pointer for CMS which may add to unloading list before 973 // purging and we don't want to rewalk the previously unloaded class loader data. 974 _saved_unloading = _unloading; 975 976 data = _head; 977 while (data != NULL) { 978 if (data->is_alive(is_alive_closure)) { 979 // clean metaspace 980 if (walk_all_metadata) { 981 data->classes_do(InstanceKlass::purge_previous_versions); 982 } 983 data->free_deallocate_list(); 984 prev = data; 985 data = data->next(); 986 continue; 987 } 988 seen_dead_loader = true; 989 ClassLoaderData* dead = data; 990 dead->unload(); 991 data = data->next(); 992 // Remove from loader list. 993 // This class loader data will no longer be found 994 // in the ClassLoaderDataGraph. 995 if (prev != NULL) { 996 prev->set_next(data); 997 } else { 998 assert(dead == _head, "sanity check"); 999 _head = data; 1000 } 1001 dead->set_next(_unloading); 1002 _unloading = dead; 1003 } 1004 1005 if (seen_dead_loader) { 1006 // Walk a ModuleEntry's reads and a PackageEntry's exports lists 1007 // to determine if there are modules on those lists that are now 1008 // dead and should be removed. A module's life cycle is equivalent 1009 // to its defining class loader's life cycle. Since a module is 1010 // considered dead if its class loader is dead, these walks must 1011 // occur after each class loader's aliveness is determined. 1012 data = _head; 1013 while (data != NULL) { 1014 if (data->packages_defined()) { 1015 data->packages()->purge_all_package_exports(); 1016 } 1017 if (data->modules_defined()) { 1018 data->modules()->purge_all_module_reads(); 1019 } 1020 data = data->next(); 1021 } 1022 1023 post_class_unload_events(); 1024 } 1025 1026 return seen_dead_loader; 1027} 1028 1029void ClassLoaderDataGraph::purge() { 1030 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 1031 ClassLoaderData* list = _unloading; 1032 _unloading = NULL; 1033 ClassLoaderData* next = list; 1034 bool classes_unloaded = false; 1035 while (next != NULL) { 1036 ClassLoaderData* purge_me = next; 1037 next = purge_me->next(); 1038 delete purge_me; 1039 classes_unloaded = true; 1040 } 1041 if (classes_unloaded) { 1042 Metaspace::purge(); 1043 set_metaspace_oom(false); 1044 } 1045} 1046 1047void ClassLoaderDataGraph::post_class_unload_events(void) { 1048#if INCLUDE_TRACE 1049 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 1050 if (Tracing::enabled()) { 1051 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) { 1052 assert(_unloading != NULL, "need class loader data unload list!"); 1053 _class_unload_time = Ticks::now(); 1054 classes_unloading_do(&class_unload_event); 1055 } 1056 Tracing::on_unloading_classes(); 1057 } 1058#endif 1059} 1060 1061// CDS support 1062 1063// Global metaspaces for writing information to the shared archive. When 1064// application CDS is supported, we may need one per metaspace, so this 1065// sort of looks like it. 1066Metaspace* ClassLoaderData::_ro_metaspace = NULL; 1067Metaspace* ClassLoaderData::_rw_metaspace = NULL; 1068static bool _shared_metaspaces_initialized = false; 1069 1070// Initialize shared metaspaces (change to call from somewhere not lazily) 1071void ClassLoaderData::initialize_shared_metaspaces() { 1072 assert(DumpSharedSpaces, "only use this for dumping shared spaces"); 1073 assert(this == ClassLoaderData::the_null_class_loader_data(), 1074 "only supported for null loader data for now"); 1075 assert (!_shared_metaspaces_initialized, "only initialize once"); 1076 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 1077 _ro_metaspace = new Metaspace(_metaspace_lock, Metaspace::ROMetaspaceType); 1078 _rw_metaspace = new Metaspace(_metaspace_lock, Metaspace::ReadWriteMetaspaceType); 1079 _shared_metaspaces_initialized = true; 1080} 1081 1082Metaspace* ClassLoaderData::ro_metaspace() { 1083 assert(_ro_metaspace != NULL, "should already be initialized"); 1084 return _ro_metaspace; 1085} 1086 1087Metaspace* ClassLoaderData::rw_metaspace() { 1088 assert(_rw_metaspace != NULL, "should already be initialized"); 1089 return _rw_metaspace; 1090} 1091 1092ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic() 1093 : _next_klass(NULL) { 1094 ClassLoaderData* cld = ClassLoaderDataGraph::_head; 1095 Klass* klass = NULL; 1096 1097 // Find the first klass in the CLDG. 1098 while (cld != NULL) { 1099 assert_locked_or_safepoint(cld->metaspace_lock()); 1100 klass = cld->_klasses; 1101 if (klass != NULL) { 1102 _next_klass = klass; 1103 return; 1104 } 1105 cld = cld->next(); 1106 } 1107} 1108 1109Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) { 1110 Klass* next = klass->next_link(); 1111 if (next != NULL) { 1112 return next; 1113 } 1114 1115 // No more klasses in the current CLD. Time to find a new CLD. 1116 ClassLoaderData* cld = klass->class_loader_data(); 1117 assert_locked_or_safepoint(cld->metaspace_lock()); 1118 while (next == NULL) { 1119 cld = cld->next(); 1120 if (cld == NULL) { 1121 break; 1122 } 1123 next = cld->_klasses; 1124 } 1125 1126 return next; 1127} 1128 1129Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() { 1130 Klass* head = _next_klass; 1131 1132 while (head != NULL) { 1133 Klass* next = next_klass_in_cldg(head); 1134 1135 Klass* old_head = (Klass*)Atomic::cmpxchg_ptr(next, &_next_klass, head); 1136 1137 if (old_head == head) { 1138 return head; // Won the CAS. 1139 } 1140 1141 head = old_head; 1142 } 1143 1144 // Nothing more for the iterator to hand out. 1145 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head)); 1146 return NULL; 1147} 1148 1149ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() { 1150 _data = ClassLoaderDataGraph::_head; 1151} 1152 1153ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {} 1154 1155#ifndef PRODUCT 1156// callable from debugger 1157extern "C" int print_loader_data_graph() { 1158 ClassLoaderDataGraph::dump_on(tty); 1159 return 0; 1160} 1161 1162void ClassLoaderDataGraph::verify() { 1163 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 1164 data->verify(); 1165 } 1166} 1167 1168void ClassLoaderDataGraph::dump_on(outputStream * const out) { 1169 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 1170 data->dump(out); 1171 } 1172 MetaspaceAux::dump(out); 1173} 1174#endif // PRODUCT 1175 1176void ClassLoaderData::print_value_on(outputStream* out) const { 1177 if (class_loader() == NULL) { 1178 out->print("NULL class_loader"); 1179 } else { 1180 out->print("class loader " INTPTR_FORMAT " ", p2i(this)); 1181 class_loader()->print_value_on(out); 1182 } 1183} 1184 1185#if INCLUDE_TRACE 1186 1187Ticks ClassLoaderDataGraph::_class_unload_time; 1188 1189void ClassLoaderDataGraph::class_unload_event(Klass* const k) { 1190 assert(k != NULL, "invariant"); 1191 1192 // post class unload event 1193 EventClassUnload event(UNTIMED); 1194 event.set_endtime(_class_unload_time); 1195 event.set_unloadedClass(k); 1196 oop defining_class_loader = k->class_loader(); 1197 event.set_definingClassLoader(defining_class_loader != NULL ? 1198 defining_class_loader->klass() : (Klass*)NULL); 1199 event.commit(); 1200} 1201 1202#endif // INCLUDE_TRACE 1203