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