1 /* 2 * Copyright (c) 2012, 2015, 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 // extension, 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/systemDictionary.hpp" 55 #include "code/codeCache.hpp" 56 #include "gc/shared/gcLocker.hpp" 57 #include "memory/metadataFactory.hpp" 58 #include "memory/metaspaceShared.hpp" 59 #include "memory/oopFactory.hpp" 60 #include "oops/objArrayOop.inline.hpp" 61 #include "oops/oop.inline.hpp" 62 #include "runtime/atomic.inline.hpp" 63 #include "runtime/jniHandles.hpp" 64 #include "runtime/mutex.hpp" 65 #include "runtime/safepoint.hpp" 66 #include "runtime/synchronizer.hpp" 67 #include "utilities/growableArray.hpp" 68 #include "utilities/macros.hpp" 69 #include "utilities/ostream.hpp" 70 #if INCLUDE_TRACE 71 #include "trace/tracing.hpp" 72 #endif 73 74 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL; 75 76 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous, Dependencies dependencies) : 77 _class_loader(h_class_loader()), 78 _is_anonymous(is_anonymous), 79 // An anonymous class loader data doesn't have anything to keep 80 // it from being unloaded during parsing of the anonymous class. 81 // The null-class-loader should always be kept alive. 82 _keep_alive(is_anonymous || h_class_loader.is_null()), 83 _metaspace(NULL), _unloading(false), _klasses(NULL), 84 _claimed(0), _jmethod_ids(NULL), _handles(NULL), _deallocate_list(NULL), 85 _next(NULL), _dependencies(dependencies), _shared_class_loader_id(-1), 86 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true, 87 Monitor::_safepoint_check_never)) { 88 // empty 89 } 90 91 void ClassLoaderData::init_dependencies(TRAPS) { 92 assert(!Universe::is_fully_initialized(), "should only be called when initializing"); 93 assert(is_the_null_class_loader_data(), "should only call this for the null class loader"); 94 _dependencies.init(CHECK); 95 } 96 97 void ClassLoaderData::Dependencies::init(TRAPS) { 98 // Create empty dependencies array to add to. CMS requires this to be 99 // an oop so that it can track additions via card marks. We think. 100 _list_head = oopFactory::new_objectArray(2, CHECK); 101 } 102 103 bool ClassLoaderData::claim() { 104 if (_claimed == 1) { 105 return false; 106 } 107 108 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0; 109 } 110 111 void ClassLoaderData::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 112 if (must_claim && !claim()) { 113 return; 114 } 115 116 f->do_oop(&_class_loader); 117 _dependencies.oops_do(f); 118 _handles->oops_do(f); 119 if (klass_closure != NULL) { 120 classes_do(klass_closure); 121 } 122 } 123 124 void ClassLoaderData::Dependencies::oops_do(OopClosure* f) { 125 f->do_oop((oop*)&_list_head); 126 } 127 128 void ClassLoaderData::classes_do(KlassClosure* klass_closure) { 129 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 130 klass_closure->do_klass(k); 131 assert(k != k->next_link(), "no loops!"); 132 } 133 } 134 135 void ClassLoaderData::classes_do(void f(Klass * const)) { 136 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 137 f(k); 138 } 139 } 140 141 void ClassLoaderData::methods_do(void f(Method*)) { 142 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 143 if (k->is_instance_klass()) { 144 InstanceKlass::cast(k)->methods_do(f); 145 } 146 } 147 } 148 149 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) { 150 // Lock to avoid classes being modified/added/removed during iteration 151 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 152 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 153 // Do not filter ArrayKlass oops here... 154 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) { 155 klass_closure->do_klass(k); 156 } 157 } 158 } 159 160 void ClassLoaderData::classes_do(void f(InstanceKlass*)) { 161 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 162 if (k->is_instance_klass()) { 163 f(InstanceKlass::cast(k)); 164 } 165 assert(k != k->next_link(), "no loops!"); 166 } 167 } 168 169 void ClassLoaderData::record_dependency(const Klass* k, TRAPS) { 170 assert(k != NULL, "invariant"); 171 172 ClassLoaderData * const from_cld = this; 173 ClassLoaderData * const to_cld = k->class_loader_data(); 174 175 // Dependency to the null class loader data doesn't need to be recorded 176 // because the null class loader data never goes away. 177 if (to_cld->is_the_null_class_loader_data()) { 178 return; 179 } 180 181 oop to; 182 if (to_cld->is_anonymous()) { 183 // Anonymous class dependencies are through the mirror. 184 to = k->java_mirror(); 185 } else { 186 to = to_cld->class_loader(); 187 188 // If from_cld is anonymous, even if it's class_loader is a parent of 'to' 189 // we still have to add it. The class_loader won't keep from_cld alive. 190 if (!from_cld->is_anonymous()) { 191 // Check that this dependency isn't from the same or parent class_loader 192 oop from = from_cld->class_loader(); 193 194 oop curr = from; 195 while (curr != NULL) { 196 if (curr == to) { 197 return; // this class loader is in the parent list, no need to add it. 198 } 199 curr = java_lang_ClassLoader::parent(curr); 200 } 201 } 202 } 203 204 // It's a dependency we won't find through GC, add it. This is relatively rare 205 // Must handle over GC point. 206 Handle dependency(THREAD, to); 207 from_cld->_dependencies.add(dependency, CHECK); 208 } 209 210 211 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) { 212 // Check first if this dependency is already in the list. 213 // Save a pointer to the last to add to under the lock. 214 objArrayOop ok = _list_head; 215 objArrayOop last = NULL; 216 while (ok != NULL) { 217 last = ok; 218 if (ok->obj_at(0) == dependency()) { 219 // Don't need to add it 220 return; 221 } 222 ok = (objArrayOop)ok->obj_at(1); 223 } 224 225 // Must handle over GC points 226 assert (last != NULL, "dependencies should be initialized"); 227 objArrayHandle last_handle(THREAD, last); 228 229 // Create a new dependency node with fields for (class_loader or mirror, next) 230 objArrayOop deps = oopFactory::new_objectArray(2, CHECK); 231 deps->obj_at_put(0, dependency()); 232 233 // Must handle over GC points 234 objArrayHandle new_dependency(THREAD, deps); 235 236 // Add the dependency under lock 237 locked_add(last_handle, new_dependency, THREAD); 238 } 239 240 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle, 241 objArrayHandle new_dependency, 242 Thread* THREAD) { 243 244 // Have to lock and put the new dependency on the end of the dependency 245 // array so the card mark for CMS sees that this dependency is new. 246 // Can probably do this lock free with some effort. 247 ObjectLocker ol(Handle(THREAD, _list_head), THREAD); 248 249 oop loader_or_mirror = new_dependency->obj_at(0); 250 251 // Since the dependencies are only added, add to the end. 252 objArrayOop end = last_handle(); 253 objArrayOop last = NULL; 254 while (end != NULL) { 255 last = end; 256 // check again if another thread added it to the end. 257 if (end->obj_at(0) == loader_or_mirror) { 258 // Don't need to add it 259 return; 260 } 261 end = (objArrayOop)end->obj_at(1); 262 } 263 assert (last != NULL, "dependencies should be initialized"); 264 // fill in the first element with the oop in new_dependency. 265 if (last->obj_at(0) == NULL) { 266 last->obj_at_put(0, new_dependency->obj_at(0)); 267 } else { 268 last->obj_at_put(1, new_dependency()); 269 } 270 } 271 272 void ClassLoaderDataGraph::clear_claimed_marks() { 273 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 274 cld->clear_claimed(); 275 } 276 } 277 278 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) { 279 { 280 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 281 Klass* old_value = _klasses; 282 k->set_next_link(old_value); 283 // Make sure linked class is stable, since the class list is walked without a lock 284 OrderAccess::storestore(); 285 // link the new item into the list 286 _klasses = k; 287 } 288 289 if (publicize && TraceClassLoaderData && Verbose && k->class_loader_data() != NULL) { 290 ResourceMark rm; 291 tty->print_cr("[TraceClassLoaderData] Adding k: " PTR_FORMAT " %s to CLD: " 292 PTR_FORMAT " loader: " PTR_FORMAT " %s", 293 p2i(k), 294 k->external_name(), 295 p2i(k->class_loader_data()), 296 p2i((void *)k->class_loader()), 297 loader_name()); 298 } 299 } 300 301 // This is called by InstanceKlass::deallocate_contents() to remove the 302 // scratch_class for redefine classes. We need a lock because there it may not 303 // be called at a safepoint if there's an error. 304 void ClassLoaderData::remove_class(Klass* scratch_class) { 305 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 306 Klass* prev = NULL; 307 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 308 if (k == scratch_class) { 309 if (prev == NULL) { 310 _klasses = k->next_link(); 311 } else { 312 Klass* next = k->next_link(); 313 prev->set_next_link(next); 314 } 315 return; 316 } 317 prev = k; 318 assert(k != k->next_link(), "no loops!"); 319 } 320 ShouldNotReachHere(); // should have found this class!! 321 } 322 323 void ClassLoaderData::unload() { 324 _unloading = true; 325 326 // Tell serviceability tools these classes are unloading 327 classes_do(InstanceKlass::notify_unload_class); 328 329 if (TraceClassLoaderData) { 330 ResourceMark rm; 331 tty->print("[ClassLoaderData: unload loader data " INTPTR_FORMAT, p2i(this)); 332 tty->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()), 333 loader_name()); 334 if (is_anonymous()) { 335 tty->print(" for anonymous class " INTPTR_FORMAT " ", p2i(_klasses)); 336 } 337 tty->print_cr("]"); 338 } 339 } 340 341 oop ClassLoaderData::keep_alive_object() const { 342 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive"); 343 return is_anonymous() ? _klasses->java_mirror() : class_loader(); 344 } 345 346 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const { 347 bool alive = keep_alive() // null class loader and incomplete anonymous klasses. 348 || is_alive_closure->do_object_b(keep_alive_object()); 349 350 return alive; 351 } 352 353 354 ClassLoaderData::~ClassLoaderData() { 355 // Release C heap structures for all the classes. 356 classes_do(InstanceKlass::release_C_heap_structures); 357 358 Metaspace *m = _metaspace; 359 if (m != NULL) { 360 _metaspace = NULL; 361 // release the metaspace 362 delete m; 363 // release the handles 364 if (_handles != NULL) { 365 JNIHandleBlock::release_block(_handles); 366 _handles = NULL; 367 } 368 } 369 370 // Clear all the JNI handles for methods 371 // These aren't deallocated and are going to look like a leak, but that's 372 // needed because we can't really get rid of jmethodIDs because we don't 373 // know when native code is going to stop using them. The spec says that 374 // they're "invalid" but existing programs likely rely on their being 375 // NULL after class unloading. 376 if (_jmethod_ids != NULL) { 377 Method::clear_jmethod_ids(this); 378 } 379 // Delete lock 380 delete _metaspace_lock; 381 382 // Delete free list 383 if (_deallocate_list != NULL) { 384 delete _deallocate_list; 385 } 386 } 387 388 /** 389 * Returns true if this class loader data is for the extension class loader. 390 */ 391 bool ClassLoaderData::is_ext_class_loader_data() const { 392 return SystemDictionary::is_ext_class_loader(class_loader()); 393 } 394 395 Metaspace* ClassLoaderData::metaspace_non_null() { 396 assert(!DumpSharedSpaces, "wrong metaspace!"); 397 // If the metaspace has not been allocated, create a new one. Might want 398 // to create smaller arena for Reflection class loaders also. 399 // The reason for the delayed allocation is because some class loaders are 400 // simply for delegating with no metadata of their own. 401 if (_metaspace == NULL) { 402 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 403 // Check again if metaspace has been allocated while we were getting this lock. 404 if (_metaspace != NULL) { 405 return _metaspace; 406 } 407 if (this == the_null_class_loader_data()) { 408 assert (class_loader() == NULL, "Must be"); 409 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType)); 410 } else if (is_anonymous()) { 411 if (TraceClassLoaderData && Verbose && class_loader() != NULL) { 412 tty->print_cr("is_anonymous: %s", class_loader()->klass()->internal_name()); 413 } 414 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType)); 415 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) { 416 if (TraceClassLoaderData && Verbose && class_loader() != NULL) { 417 tty->print_cr("is_reflection: %s", class_loader()->klass()->internal_name()); 418 } 419 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType)); 420 } else { 421 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType)); 422 } 423 } 424 return _metaspace; 425 } 426 427 JNIHandleBlock* ClassLoaderData::handles() const { return _handles; } 428 void ClassLoaderData::set_handles(JNIHandleBlock* handles) { _handles = handles; } 429 430 jobject ClassLoaderData::add_handle(Handle h) { 431 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 432 if (handles() == NULL) { 433 set_handles(JNIHandleBlock::allocate_block()); 434 } 435 return handles()->allocate_handle(h()); 436 } 437 438 // Add this metadata pointer to be freed when it's safe. This is only during 439 // class unloading because Handles might point to this metadata field. 440 void ClassLoaderData::add_to_deallocate_list(Metadata* m) { 441 // Metadata in shared region isn't deleted. 442 if (!m->is_shared()) { 443 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 444 if (_deallocate_list == NULL) { 445 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true); 446 } 447 _deallocate_list->append_if_missing(m); 448 } 449 } 450 451 // Deallocate free metadata on the free list. How useful the PermGen was! 452 void ClassLoaderData::free_deallocate_list() { 453 // Don't need lock, at safepoint 454 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 455 if (_deallocate_list == NULL) { 456 return; 457 } 458 // Go backwards because this removes entries that are freed. 459 for (int i = _deallocate_list->length() - 1; i >= 0; i--) { 460 Metadata* m = _deallocate_list->at(i); 461 if (!m->on_stack()) { 462 _deallocate_list->remove_at(i); 463 // There are only three types of metadata that we deallocate directly. 464 // Cast them so they can be used by the template function. 465 if (m->is_method()) { 466 MetadataFactory::free_metadata(this, (Method*)m); 467 } else if (m->is_constantPool()) { 468 MetadataFactory::free_metadata(this, (ConstantPool*)m); 469 } else if (m->is_klass()) { 470 MetadataFactory::free_metadata(this, (InstanceKlass*)m); 471 } else { 472 ShouldNotReachHere(); 473 } 474 } else { 475 // Metadata is alive. 476 // If scratch_class is on stack then it shouldn't be on this list! 477 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(), 478 "scratch classes on this list should be dead"); 479 // Also should assert that other metadata on the list was found in handles. 480 } 481 } 482 } 483 484 // These anonymous class loaders are to contain classes used for JSR292 485 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) { 486 // Add a new class loader data to the graph. 487 return ClassLoaderDataGraph::add(loader, true, THREAD); 488 } 489 490 const char* ClassLoaderData::loader_name() { 491 // Handles null class loader 492 return SystemDictionary::loader_name(class_loader()); 493 } 494 495 #ifndef PRODUCT 496 // Define to dump klasses 497 #undef CLD_DUMP_KLASSES 498 499 void ClassLoaderData::dump(outputStream * const out) { 500 ResourceMark rm; 501 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: " PTR_FORMAT " %s {", 502 p2i(this), p2i((void *)class_loader()), 503 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name()); 504 if (claimed()) out->print(" claimed "); 505 if (is_unloading()) out->print(" unloading "); 506 out->print(" handles " INTPTR_FORMAT, p2i(handles())); 507 out->cr(); 508 if (metaspace_or_null() != NULL) { 509 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null())); 510 metaspace_or_null()->dump(out); 511 } else { 512 out->print_cr("metaspace: NULL"); 513 } 514 515 #ifdef CLD_DUMP_KLASSES 516 if (Verbose) { 517 ResourceMark rm; 518 Klass* k = _klasses; 519 while (k != NULL) { 520 out->print_cr("klass " PTR_FORMAT ", %s, CT: %d, MUT: %d", k, k->name()->as_C_string(), 521 k->has_modified_oops(), k->has_accumulated_modified_oops()); 522 assert(k != k->next_link(), "no loops!"); 523 k = k->next_link(); 524 } 525 } 526 #endif // CLD_DUMP_KLASSES 527 #undef CLD_DUMP_KLASSES 528 if (_jmethod_ids != NULL) { 529 Method::print_jmethod_ids(this, out); 530 } 531 out->print_cr("}"); 532 } 533 #endif // PRODUCT 534 535 void ClassLoaderData::verify() { 536 oop cl = class_loader(); 537 538 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same"); 539 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be"); 540 541 // Verify the integrity of the allocated space. 542 if (metaspace_or_null() != NULL) { 543 metaspace_or_null()->verify(); 544 } 545 546 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 547 guarantee(k->class_loader_data() == this, "Must be the same"); 548 k->verify(); 549 assert(k != k->next_link(), "no loops!"); 550 } 551 } 552 553 bool ClassLoaderData::contains_klass(Klass* klass) { 554 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 555 if (k == klass) return true; 556 } 557 return false; 558 } 559 560 561 // GC root of class loader data created. 562 ClassLoaderData* ClassLoaderDataGraph::_head = NULL; 563 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL; 564 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL; 565 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL; 566 567 bool ClassLoaderDataGraph::_should_purge = false; 568 bool ClassLoaderDataGraph::_metaspace_oom = false; 569 570 // Add a new class loader data node to the list. Assign the newly created 571 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field 572 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) { 573 // We need to allocate all the oops for the ClassLoaderData before allocating the 574 // actual ClassLoaderData object. 575 ClassLoaderData::Dependencies dependencies(CHECK_NULL); 576 577 No_Safepoint_Verifier no_safepoints; // we mustn't GC until we've installed the 578 // ClassLoaderData in the graph since the CLD 579 // contains unhandled oops 580 581 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies); 582 583 584 if (!is_anonymous) { 585 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader()); 586 // First, Atomically set it 587 ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL); 588 if (old != NULL) { 589 delete cld; 590 // Returns the data. 591 return old; 592 } 593 } 594 595 // We won the race, and therefore the task of adding the data to the list of 596 // class loader data 597 ClassLoaderData** list_head = &_head; 598 ClassLoaderData* next = _head; 599 600 do { 601 cld->set_next(next); 602 ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next); 603 if (exchanged == next) { 604 if (TraceClassLoaderData) { 605 ResourceMark rm; 606 tty->print("[ClassLoaderData: "); 607 tty->print("create class loader data " INTPTR_FORMAT, p2i(cld)); 608 tty->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()), 609 cld->loader_name()); 610 tty->print_cr("]"); 611 } 612 return cld; 613 } 614 next = exchanged; 615 } while (true); 616 617 } 618 619 void ClassLoaderDataGraph::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 620 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 621 cld->oops_do(f, klass_closure, must_claim); 622 } 623 } 624 625 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 626 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 627 if (cld->keep_alive()) { 628 cld->oops_do(f, klass_closure, must_claim); 629 } 630 } 631 } 632 633 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 634 if (ClassUnloading) { 635 keep_alive_oops_do(f, klass_closure, must_claim); 636 } else { 637 oops_do(f, klass_closure, must_claim); 638 } 639 } 640 641 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) { 642 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) { 643 cl->do_cld(cld); 644 } 645 } 646 647 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) { 648 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) { 649 CLDClosure* closure = cld->keep_alive() ? strong : weak; 650 if (closure != NULL) { 651 closure->do_cld(cld); 652 } 653 } 654 } 655 656 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) { 657 roots_cld_do(cl, NULL); 658 } 659 660 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) { 661 if (ClassUnloading) { 662 keep_alive_cld_do(cl); 663 } else { 664 cld_do(cl); 665 } 666 } 667 668 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) { 669 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 670 cld->classes_do(klass_closure); 671 } 672 } 673 674 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) { 675 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 676 cld->classes_do(f); 677 } 678 } 679 680 void ClassLoaderDataGraph::methods_do(void f(Method*)) { 681 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 682 cld->methods_do(f); 683 } 684 } 685 686 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) { 687 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 688 cld->loaded_classes_do(klass_closure); 689 } 690 } 691 692 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) { 693 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 694 // Only walk the head until any clds not purged from prior unloading 695 // (CMS doesn't purge right away). 696 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) { 697 cld->classes_do(f); 698 } 699 } 700 701 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() { 702 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?"); 703 704 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>(); 705 706 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true); 707 ClassLoaderData* curr = _head; 708 while (curr != _saved_head) { 709 if (!curr->claimed()) { 710 array->push(curr); 711 712 if (TraceClassLoaderData) { 713 tty->print("[ClassLoaderData] found new CLD: "); 714 curr->print_value_on(tty); 715 tty->cr(); 716 } 717 } 718 719 curr = curr->_next; 720 } 721 722 return array; 723 } 724 725 bool ClassLoaderDataGraph::unload_list_contains(const void* x) { 726 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint"); 727 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) { 728 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) { 729 return true; 730 } 731 } 732 return false; 733 } 734 735 #ifndef PRODUCT 736 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) { 737 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 738 if (loader_data == data) { 739 return true; 740 } 741 } 742 743 return false; 744 } 745 #endif // PRODUCT 746 747 748 // Move class loader data from main list to the unloaded list for unloading 749 // and deallocation later. 750 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure, 751 bool clean_previous_versions) { 752 753 ClassLoaderData* data = _head; 754 ClassLoaderData* prev = NULL; 755 bool seen_dead_loader = false; 756 757 // Mark metadata seen on the stack only so we can delete unneeded entries. 758 // Only walk all metadata, including the expensive code cache walk, for Full GC 759 // and only if class redefinition and if there's previous versions of 760 // Klasses to delete. 761 bool walk_all_metadata = clean_previous_versions && 762 JvmtiExport::has_redefined_a_class() && 763 InstanceKlass::has_previous_versions(); 764 MetadataOnStackMark md_on_stack(walk_all_metadata); 765 766 // Save previous _unloading pointer for CMS which may add to unloading list before 767 // purging and we don't want to rewalk the previously unloaded class loader data. 768 _saved_unloading = _unloading; 769 770 data = _head; 771 while (data != NULL) { 772 if (data->is_alive(is_alive_closure)) { 773 // clean metaspace 774 if (walk_all_metadata) { 775 data->classes_do(InstanceKlass::purge_previous_versions); 776 } 777 data->free_deallocate_list(); 778 prev = data; 779 data = data->next(); 780 continue; 781 } 782 seen_dead_loader = true; 783 ClassLoaderData* dead = data; 784 dead->unload(); 785 data = data->next(); 786 // Remove from loader list. 787 // This class loader data will no longer be found 788 // in the ClassLoaderDataGraph. 789 if (prev != NULL) { 790 prev->set_next(data); 791 } else { 792 assert(dead == _head, "sanity check"); 793 _head = data; 794 } 795 dead->set_next(_unloading); 796 _unloading = dead; 797 } 798 799 if (seen_dead_loader) { 800 post_class_unload_events(); 801 } 802 803 return seen_dead_loader; 804 } 805 806 void ClassLoaderDataGraph::purge() { 807 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 808 ClassLoaderData* list = _unloading; 809 _unloading = NULL; 810 ClassLoaderData* next = list; 811 bool classes_unloaded = false; 812 while (next != NULL) { 813 ClassLoaderData* purge_me = next; 814 next = purge_me->next(); 815 delete purge_me; 816 classes_unloaded = true; 817 } 818 if (classes_unloaded) { 819 Metaspace::purge(); 820 set_metaspace_oom(false); 821 } 822 } 823 824 void ClassLoaderDataGraph::post_class_unload_events(void) { 825 #if INCLUDE_TRACE 826 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 827 if (Tracing::enabled()) { 828 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) { 829 assert(_unloading != NULL, "need class loader data unload list!"); 830 _class_unload_time = Ticks::now(); 831 classes_unloading_do(&class_unload_event); 832 } 833 Tracing::on_unloading_classes(); 834 } 835 #endif 836 } 837 838 // CDS support 839 840 // Global metaspaces for writing information to the shared archive. When 841 // application CDS is supported, we may need one per metaspace, so this 842 // sort of looks like it. 843 Metaspace* ClassLoaderData::_ro_metaspace = NULL; 844 Metaspace* ClassLoaderData::_rw_metaspace = NULL; 845 static bool _shared_metaspaces_initialized = false; 846 847 // Initialize shared metaspaces (change to call from somewhere not lazily) 848 void ClassLoaderData::initialize_shared_metaspaces() { 849 assert(DumpSharedSpaces, "only use this for dumping shared spaces"); 850 assert(this == ClassLoaderData::the_null_class_loader_data(), 851 "only supported for null loader data for now"); 852 assert (!_shared_metaspaces_initialized, "only initialize once"); 853 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 854 _ro_metaspace = new Metaspace(_metaspace_lock, Metaspace::ROMetaspaceType); 855 _rw_metaspace = new Metaspace(_metaspace_lock, Metaspace::ReadWriteMetaspaceType); 856 _shared_metaspaces_initialized = true; 857 } 858 859 Metaspace* ClassLoaderData::ro_metaspace() { 860 assert(_ro_metaspace != NULL, "should already be initialized"); 861 return _ro_metaspace; 862 } 863 864 Metaspace* ClassLoaderData::rw_metaspace() { 865 assert(_rw_metaspace != NULL, "should already be initialized"); 866 return _rw_metaspace; 867 } 868 869 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic() 870 : _next_klass(NULL) { 871 ClassLoaderData* cld = ClassLoaderDataGraph::_head; 872 Klass* klass = NULL; 873 874 // Find the first klass in the CLDG. 875 while (cld != NULL) { 876 klass = cld->_klasses; 877 if (klass != NULL) { 878 _next_klass = klass; 879 return; 880 } 881 cld = cld->next(); 882 } 883 } 884 885 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) { 886 Klass* next = klass->next_link(); 887 if (next != NULL) { 888 return next; 889 } 890 891 // No more klasses in the current CLD. Time to find a new CLD. 892 ClassLoaderData* cld = klass->class_loader_data(); 893 while (next == NULL) { 894 cld = cld->next(); 895 if (cld == NULL) { 896 break; 897 } 898 next = cld->_klasses; 899 } 900 901 return next; 902 } 903 904 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() { 905 Klass* head = _next_klass; 906 907 while (head != NULL) { 908 Klass* next = next_klass_in_cldg(head); 909 910 Klass* old_head = (Klass*)Atomic::cmpxchg_ptr(next, &_next_klass, head); 911 912 if (old_head == head) { 913 return head; // Won the CAS. 914 } 915 916 head = old_head; 917 } 918 919 // Nothing more for the iterator to hand out. 920 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head)); 921 return NULL; 922 } 923 924 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() { 925 _data = ClassLoaderDataGraph::_head; 926 } 927 928 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {} 929 930 #ifndef PRODUCT 931 // callable from debugger 932 extern "C" int print_loader_data_graph() { 933 ClassLoaderDataGraph::dump_on(tty); 934 return 0; 935 } 936 937 void ClassLoaderDataGraph::verify() { 938 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 939 data->verify(); 940 } 941 } 942 943 void ClassLoaderDataGraph::dump_on(outputStream * const out) { 944 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 945 data->dump(out); 946 } 947 MetaspaceAux::dump(out); 948 } 949 #endif // PRODUCT 950 951 void ClassLoaderData::print_value_on(outputStream* out) const { 952 if (class_loader() == NULL) { 953 out->print("NULL class_loader"); 954 } else { 955 out->print("class loader " INTPTR_FORMAT, p2i(this)); 956 class_loader()->print_value_on(out); 957 } 958 } 959 960 #if INCLUDE_TRACE 961 962 Ticks ClassLoaderDataGraph::_class_unload_time; 963 964 void ClassLoaderDataGraph::class_unload_event(Klass* const k) { 965 966 // post class unload event 967 EventClassUnload event(UNTIMED); 968 event.set_endtime(_class_unload_time); 969 event.set_unloadedClass(k); 970 oop defining_class_loader = k->class_loader(); 971 event.set_definingClassLoader(defining_class_loader != NULL ? 972 defining_class_loader->klass() : (Klass*)NULL); 973 event.commit(); 974 } 975 976 #endif // INCLUDE_TRACE