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