1 /* 2 * Copyright (c) 2012, 2014, 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 "memory/gcLocker.hpp" 57 #include "memory/metadataFactory.hpp" 58 #include "memory/metaspaceShared.hpp" 59 #include "memory/oopFactory.hpp" 60 #include "runtime/atomic.inline.hpp" 61 #include "runtime/jniHandles.hpp" 62 #include "runtime/mutex.hpp" 63 #include "runtime/safepoint.hpp" 64 #include "runtime/synchronizer.hpp" 65 #include "utilities/growableArray.hpp" 66 #include "utilities/macros.hpp" 67 #include "utilities/ostream.hpp" 68 #if INCLUDE_TRACE 69 #include "trace/tracing.hpp" 70 #endif 71 72 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL; 73 74 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous, Dependencies dependencies) : 75 _class_loader(h_class_loader()), 76 _is_anonymous(is_anonymous), 77 // An anonymous class loader data doesn't have anything to keep 78 // it from being unloaded during parsing of the anonymous class. 79 // The null-class-loader should always be kept alive. 80 _keep_alive(is_anonymous || h_class_loader.is_null()), 81 _metaspace(NULL), _unloading(false), _klasses(NULL), 82 _claimed(0), _jmethod_ids(NULL), _handles(NULL), _deallocate_list(NULL), 83 _next(NULL), _dependencies(dependencies), 84 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true, 85 Monitor::_safepoint_check_never)) { 86 // empty 87 } 88 89 void ClassLoaderData::init_dependencies(TRAPS) { 90 assert(!Universe::is_fully_initialized(), "should only be called when initializing"); 91 assert(is_the_null_class_loader_data(), "should only call this for the null class loader"); 92 _dependencies.init(CHECK); 93 } 94 95 void ClassLoaderData::Dependencies::init(TRAPS) { 96 // Create empty dependencies array to add to. CMS requires this to be 97 // an oop so that it can track additions via card marks. We think. 98 _list_head = oopFactory::new_objectArray(2, CHECK); 99 } 100 101 bool ClassLoaderData::claim() { 102 if (_claimed == 1) { 103 return false; 104 } 105 106 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0; 107 } 108 109 void ClassLoaderData::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 110 if (must_claim && !claim()) { 111 return; 112 } 113 114 f->do_oop(&_class_loader); 115 _dependencies.oops_do(f); 116 _handles->oops_do(f); 117 if (klass_closure != NULL) { 118 classes_do(klass_closure); 119 } 120 } 121 122 void ClassLoaderData::Dependencies::oops_do(OopClosure* f) { 123 f->do_oop((oop*)&_list_head); 124 } 125 126 void ClassLoaderData::classes_do(KlassClosure* klass_closure) { 127 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 128 klass_closure->do_klass(k); 129 assert(k != k->next_link(), "no loops!"); 130 } 131 } 132 133 void ClassLoaderData::classes_do(void f(Klass * const)) { 134 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 135 f(k); 136 } 137 } 138 139 void ClassLoaderData::methods_do(void f(Method*)) { 140 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 141 if (k->oop_is_instance()) { 142 InstanceKlass::cast(k)->methods_do(f); 143 } 144 } 145 } 146 147 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) { 148 // Lock to avoid classes being modified/added/removed during iteration 149 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 150 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 151 // Do not filter ArrayKlass oops here... 152 if (k->oop_is_array() || (k->oop_is_instance() && InstanceKlass::cast(k)->is_loaded())) { 153 klass_closure->do_klass(k); 154 } 155 } 156 } 157 158 void ClassLoaderData::classes_do(void f(InstanceKlass*)) { 159 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 160 if (k->oop_is_instance()) { 161 f(InstanceKlass::cast(k)); 162 } 163 assert(k != k->next_link(), "no loops!"); 164 } 165 } 166 167 void ClassLoaderData::record_dependency(Klass* k, TRAPS) { 168 ClassLoaderData * const from_cld = this; 169 ClassLoaderData * const to_cld = k->class_loader_data(); 170 171 // Dependency to the null class loader data doesn't need to be recorded 172 // because the null class loader data never goes away. 173 if (to_cld->is_the_null_class_loader_data()) { 174 return; 175 } 176 177 oop to; 178 if (to_cld->is_anonymous()) { 179 // Anonymous class dependencies are through the mirror. 180 to = k->java_mirror(); 181 } else { 182 to = to_cld->class_loader(); 183 184 // If from_cld is anonymous, even if it's class_loader is a parent of 'to' 185 // we still have to add it. The class_loader won't keep from_cld alive. 186 if (!from_cld->is_anonymous()) { 187 // Check that this dependency isn't from the same or parent class_loader 188 oop from = from_cld->class_loader(); 189 190 oop curr = from; 191 while (curr != NULL) { 192 if (curr == to) { 193 return; // this class loader is in the parent list, no need to add it. 194 } 195 curr = java_lang_ClassLoader::parent(curr); 196 } 197 } 198 } 199 200 // It's a dependency we won't find through GC, add it. This is relatively rare 201 // Must handle over GC point. 202 Handle dependency(THREAD, to); 203 from_cld->_dependencies.add(dependency, CHECK); 204 } 205 206 207 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) { 208 // Check first if this dependency is already in the list. 209 // Save a pointer to the last to add to under the lock. 210 objArrayOop ok = _list_head; 211 objArrayOop last = NULL; 212 while (ok != NULL) { 213 last = ok; 214 if (ok->obj_at(0) == dependency()) { 215 // Don't need to add it 216 return; 217 } 218 ok = (objArrayOop)ok->obj_at(1); 219 } 220 221 // Must handle over GC points 222 assert (last != NULL, "dependencies should be initialized"); 223 objArrayHandle last_handle(THREAD, last); 224 225 // Create a new dependency node with fields for (class_loader or mirror, next) 226 objArrayOop deps = oopFactory::new_objectArray(2, CHECK); 227 deps->obj_at_put(0, dependency()); 228 229 // Must handle over GC points 230 objArrayHandle new_dependency(THREAD, deps); 231 232 // Add the dependency under lock 233 locked_add(last_handle, new_dependency, THREAD); 234 } 235 236 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle, 237 objArrayHandle new_dependency, 238 Thread* THREAD) { 239 240 // Have to lock and put the new dependency on the end of the dependency 241 // array so the card mark for CMS sees that this dependency is new. 242 // Can probably do this lock free with some effort. 243 ObjectLocker ol(Handle(THREAD, _list_head), THREAD); 244 245 oop loader_or_mirror = new_dependency->obj_at(0); 246 247 // Since the dependencies are only added, add to the end. 248 objArrayOop end = last_handle(); 249 objArrayOop last = NULL; 250 while (end != NULL) { 251 last = end; 252 // check again if another thread added it to the end. 253 if (end->obj_at(0) == loader_or_mirror) { 254 // Don't need to add it 255 return; 256 } 257 end = (objArrayOop)end->obj_at(1); 258 } 259 assert (last != NULL, "dependencies should be initialized"); 260 // fill in the first element with the oop in new_dependency. 261 if (last->obj_at(0) == NULL) { 262 last->obj_at_put(0, new_dependency->obj_at(0)); 263 } else { 264 last->obj_at_put(1, new_dependency()); 265 } 266 } 267 268 void ClassLoaderDataGraph::clear_claimed_marks() { 269 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 270 cld->clear_claimed(); 271 } 272 } 273 274 void ClassLoaderData::add_class(Klass* k) { 275 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 276 Klass* old_value = _klasses; 277 k->set_next_link(old_value); 278 // Make sure linked class is stable, since the class list is walked without a lock 279 OrderAccess::storestore(); 280 // link the new item into the list 281 _klasses = k; 282 283 if (TraceClassLoaderData && Verbose && k->class_loader_data() != NULL) { 284 ResourceMark rm; 285 tty->print_cr("[TraceClassLoaderData] Adding k: " PTR_FORMAT " %s to CLD: " 286 PTR_FORMAT " loader: " PTR_FORMAT " %s", 287 p2i(k), 288 k->external_name(), 289 p2i(k->class_loader_data()), 290 p2i((void *)k->class_loader()), 291 loader_name()); 292 } 293 } 294 295 // This is called by InstanceKlass::deallocate_contents() to remove the 296 // scratch_class for redefine classes. We need a lock because there it may not 297 // be called at a safepoint if there's an error. 298 void ClassLoaderData::remove_class(Klass* scratch_class) { 299 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 300 Klass* prev = NULL; 301 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 302 if (k == scratch_class) { 303 if (prev == NULL) { 304 _klasses = k->next_link(); 305 } else { 306 Klass* next = k->next_link(); 307 prev->set_next_link(next); 308 } 309 return; 310 } 311 prev = k; 312 assert(k != k->next_link(), "no loops!"); 313 } 314 ShouldNotReachHere(); // should have found this class!! 315 } 316 317 void ClassLoaderData::unload() { 318 _unloading = true; 319 320 // Tell serviceability tools these classes are unloading 321 classes_do(InstanceKlass::notify_unload_class); 322 323 if (TraceClassLoaderData) { 324 ResourceMark rm; 325 tty->print("[ClassLoaderData: unload loader data " INTPTR_FORMAT, p2i(this)); 326 tty->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()), 327 loader_name()); 328 if (is_anonymous()) { 329 tty->print(" for anonymous class " INTPTR_FORMAT " ", p2i(_klasses)); 330 } 331 tty->print_cr("]"); 332 } 333 } 334 335 oop ClassLoaderData::keep_alive_object() const { 336 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive"); 337 return is_anonymous() ? _klasses->java_mirror() : class_loader(); 338 } 339 340 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const { 341 bool alive = keep_alive() // null class loader and incomplete anonymous klasses. 342 || is_alive_closure->do_object_b(keep_alive_object()); 343 344 return alive; 345 } 346 347 348 ClassLoaderData::~ClassLoaderData() { 349 // Release C heap structures for all the classes. 350 classes_do(InstanceKlass::release_C_heap_structures); 351 352 Metaspace *m = _metaspace; 353 if (m != NULL) { 354 _metaspace = NULL; 355 // release the metaspace 356 delete m; 357 // release the handles 358 if (_handles != NULL) { 359 JNIHandleBlock::release_block(_handles); 360 _handles = NULL; 361 } 362 } 363 364 // Clear all the JNI handles for methods 365 // These aren't deallocated and are going to look like a leak, but that's 366 // needed because we can't really get rid of jmethodIDs because we don't 367 // know when native code is going to stop using them. The spec says that 368 // they're "invalid" but existing programs likely rely on their being 369 // NULL after class unloading. 370 if (_jmethod_ids != NULL) { 371 Method::clear_jmethod_ids(this); 372 } 373 // Delete lock 374 delete _metaspace_lock; 375 376 // Delete free list 377 if (_deallocate_list != NULL) { 378 delete _deallocate_list; 379 } 380 } 381 382 /** 383 * Returns true if this class loader data is for the extension class loader. 384 */ 385 bool ClassLoaderData::is_ext_class_loader_data() const { 386 return SystemDictionary::is_ext_class_loader(class_loader()); 387 } 388 389 Metaspace* ClassLoaderData::metaspace_non_null() { 390 assert(!DumpSharedSpaces, "wrong metaspace!"); 391 // If the metaspace has not been allocated, create a new one. Might want 392 // to create smaller arena for Reflection class loaders also. 393 // The reason for the delayed allocation is because some class loaders are 394 // simply for delegating with no metadata of their own. 395 if (_metaspace == NULL) { 396 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 397 // Check again if metaspace has been allocated while we were getting this lock. 398 if (_metaspace != NULL) { 399 return _metaspace; 400 } 401 if (this == the_null_class_loader_data()) { 402 assert (class_loader() == NULL, "Must be"); 403 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType)); 404 } else if (is_anonymous()) { 405 if (TraceClassLoaderData && Verbose && class_loader() != NULL) { 406 tty->print_cr("is_anonymous: %s", class_loader()->klass()->internal_name()); 407 } 408 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType)); 409 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) { 410 if (TraceClassLoaderData && Verbose && class_loader() != NULL) { 411 tty->print_cr("is_reflection: %s", class_loader()->klass()->internal_name()); 412 } 413 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType)); 414 } else { 415 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType)); 416 } 417 } 418 return _metaspace; 419 } 420 421 JNIHandleBlock* ClassLoaderData::handles() const { return _handles; } 422 void ClassLoaderData::set_handles(JNIHandleBlock* handles) { _handles = handles; } 423 424 jobject ClassLoaderData::add_handle(Handle h) { 425 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 426 if (handles() == NULL) { 427 set_handles(JNIHandleBlock::allocate_block()); 428 } 429 return handles()->allocate_handle(h()); 430 } 431 432 // Add this metadata pointer to be freed when it's safe. This is only during 433 // class unloading because Handles might point to this metadata field. 434 void ClassLoaderData::add_to_deallocate_list(Metadata* m) { 435 // Metadata in shared region isn't deleted. 436 if (!m->is_shared()) { 437 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 438 if (_deallocate_list == NULL) { 439 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true); 440 } 441 _deallocate_list->append_if_missing(m); 442 } 443 } 444 445 // Deallocate free metadata on the free list. How useful the PermGen was! 446 void ClassLoaderData::free_deallocate_list() { 447 // Don't need lock, at safepoint 448 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 449 if (_deallocate_list == NULL) { 450 return; 451 } 452 // Go backwards because this removes entries that are freed. 453 for (int i = _deallocate_list->length() - 1; i >= 0; i--) { 454 Metadata* m = _deallocate_list->at(i); 455 if (!m->on_stack()) { 456 _deallocate_list->remove_at(i); 457 // There are only three types of metadata that we deallocate directly. 458 // Cast them so they can be used by the template function. 459 if (m->is_method()) { 460 MetadataFactory::free_metadata(this, (Method*)m); 461 } else if (m->is_constantPool()) { 462 MetadataFactory::free_metadata(this, (ConstantPool*)m); 463 } else if (m->is_klass()) { 464 MetadataFactory::free_metadata(this, (InstanceKlass*)m); 465 } else { 466 ShouldNotReachHere(); 467 } 468 } 469 } 470 } 471 472 // These anonymous class loaders are to contain classes used for JSR292 473 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) { 474 // Add a new class loader data to the graph. 475 return ClassLoaderDataGraph::add(loader, true, CHECK_NULL); 476 } 477 478 const char* ClassLoaderData::loader_name() { 479 // Handles null class loader 480 return SystemDictionary::loader_name(class_loader()); 481 } 482 483 #ifndef PRODUCT 484 // Define to dump klasses 485 #undef CLD_DUMP_KLASSES 486 487 void ClassLoaderData::dump(outputStream * const out) { 488 ResourceMark rm; 489 out->print("ClassLoaderData CLD: "PTR_FORMAT", loader: "PTR_FORMAT", loader_klass: "PTR_FORMAT" %s {", 490 p2i(this), p2i((void *)class_loader()), 491 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name()); 492 if (claimed()) out->print(" claimed "); 493 if (is_unloading()) out->print(" unloading "); 494 out->print(" handles " INTPTR_FORMAT, p2i(handles())); 495 out->cr(); 496 if (metaspace_or_null() != NULL) { 497 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null())); 498 metaspace_or_null()->dump(out); 499 } else { 500 out->print_cr("metaspace: NULL"); 501 } 502 503 #ifdef CLD_DUMP_KLASSES 504 if (Verbose) { 505 ResourceMark rm; 506 Klass* k = _klasses; 507 while (k != NULL) { 508 out->print_cr("klass "PTR_FORMAT", %s, CT: %d, MUT: %d", k, k->name()->as_C_string(), 509 k->has_modified_oops(), k->has_accumulated_modified_oops()); 510 assert(k != k->next_link(), "no loops!"); 511 k = k->next_link(); 512 } 513 } 514 #endif // CLD_DUMP_KLASSES 515 #undef CLD_DUMP_KLASSES 516 if (_jmethod_ids != NULL) { 517 Method::print_jmethod_ids(this, out); 518 } 519 out->print_cr("}"); 520 } 521 #endif // PRODUCT 522 523 void ClassLoaderData::verify() { 524 oop cl = class_loader(); 525 526 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same"); 527 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be"); 528 529 // Verify the integrity of the allocated space. 530 if (metaspace_or_null() != NULL) { 531 metaspace_or_null()->verify(); 532 } 533 534 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 535 guarantee(k->class_loader_data() == this, "Must be the same"); 536 k->verify(); 537 assert(k != k->next_link(), "no loops!"); 538 } 539 } 540 541 bool ClassLoaderData::contains_klass(Klass* klass) { 542 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 543 if (k == klass) return true; 544 } 545 return false; 546 } 547 548 549 // GC root of class loader data created. 550 ClassLoaderData* ClassLoaderDataGraph::_head = NULL; 551 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL; 552 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL; 553 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL; 554 555 bool ClassLoaderDataGraph::_should_purge = false; 556 bool ClassLoaderDataGraph::_metaspace_oom = false; 557 558 // Add a new class loader data node to the list. Assign the newly created 559 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field 560 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) { 561 // We need to allocate all the oops for the ClassLoaderData before allocating the 562 // actual ClassLoaderData object. 563 ClassLoaderData::Dependencies dependencies(CHECK_NULL); 564 565 No_Safepoint_Verifier no_safepoints; // we mustn't GC until we've installed the 566 // ClassLoaderData in the graph since the CLD 567 // contains unhandled oops 568 569 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies); 570 571 572 if (!is_anonymous) { 573 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader()); 574 // First, Atomically set it 575 ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL); 576 if (old != NULL) { 577 delete cld; 578 // Returns the data. 579 return old; 580 } 581 } 582 583 // We won the race, and therefore the task of adding the data to the list of 584 // class loader data 585 ClassLoaderData** list_head = &_head; 586 ClassLoaderData* next = _head; 587 588 do { 589 cld->set_next(next); 590 ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next); 591 if (exchanged == next) { 592 if (TraceClassLoaderData) { 593 ResourceMark rm; 594 tty->print("[ClassLoaderData: "); 595 tty->print("create class loader data " INTPTR_FORMAT, p2i(cld)); 596 tty->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()), 597 cld->loader_name()); 598 tty->print_cr("]"); 599 } 600 return cld; 601 } 602 next = exchanged; 603 } while (true); 604 605 } 606 607 void ClassLoaderDataGraph::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 608 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 609 cld->oops_do(f, klass_closure, must_claim); 610 } 611 } 612 613 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 614 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 615 if (cld->keep_alive()) { 616 cld->oops_do(f, klass_closure, must_claim); 617 } 618 } 619 } 620 621 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 622 if (ClassUnloading) { 623 keep_alive_oops_do(f, klass_closure, must_claim); 624 } else { 625 oops_do(f, klass_closure, must_claim); 626 } 627 } 628 629 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) { 630 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) { 631 cl->do_cld(cld); 632 } 633 } 634 635 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) { 636 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) { 637 CLDClosure* closure = cld->keep_alive() ? strong : weak; 638 if (closure != NULL) { 639 closure->do_cld(cld); 640 } 641 } 642 } 643 644 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) { 645 roots_cld_do(cl, NULL); 646 } 647 648 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) { 649 if (ClassUnloading) { 650 keep_alive_cld_do(cl); 651 } else { 652 cld_do(cl); 653 } 654 } 655 656 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) { 657 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 658 cld->classes_do(klass_closure); 659 } 660 } 661 662 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) { 663 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 664 cld->classes_do(f); 665 } 666 } 667 668 void ClassLoaderDataGraph::methods_do(void f(Method*)) { 669 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 670 cld->methods_do(f); 671 } 672 } 673 674 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) { 675 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 676 cld->loaded_classes_do(klass_closure); 677 } 678 } 679 680 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) { 681 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 682 // Only walk the head until any clds not purged from prior unloading 683 // (CMS doesn't purge right away). 684 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) { 685 cld->classes_do(f); 686 } 687 } 688 689 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() { 690 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?"); 691 692 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>(); 693 694 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true); 695 ClassLoaderData* curr = _head; 696 while (curr != _saved_head) { 697 if (!curr->claimed()) { 698 array->push(curr); 699 700 if (TraceClassLoaderData) { 701 tty->print("[ClassLoaderData] found new CLD: "); 702 curr->print_value_on(tty); 703 tty->cr(); 704 } 705 } 706 707 curr = curr->_next; 708 } 709 710 return array; 711 } 712 713 bool ClassLoaderDataGraph::unload_list_contains(const void* x) { 714 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint"); 715 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) { 716 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) { 717 return true; 718 } 719 } 720 return false; 721 } 722 723 #ifndef PRODUCT 724 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) { 725 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 726 if (loader_data == data) { 727 return true; 728 } 729 } 730 731 return false; 732 } 733 #endif // PRODUCT 734 735 736 // Move class loader data from main list to the unloaded list for unloading 737 // and deallocation later. 738 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure, bool clean_alive) { 739 ClassLoaderData* data = _head; 740 ClassLoaderData* prev = NULL; 741 bool seen_dead_loader = false; 742 743 // Save previous _unloading pointer for CMS which may add to unloading list before 744 // purging and we don't want to rewalk the previously unloaded class loader data. 745 _saved_unloading = _unloading; 746 747 data = _head; 748 while (data != NULL) { 749 if (data->is_alive(is_alive_closure)) { 750 prev = data; 751 data = data->next(); 752 continue; 753 } 754 seen_dead_loader = true; 755 ClassLoaderData* dead = data; 756 dead->unload(); 757 data = data->next(); 758 // Remove from loader list. 759 // This class loader data will no longer be found 760 // in the ClassLoaderDataGraph. 761 if (prev != NULL) { 762 prev->set_next(data); 763 } else { 764 assert(dead == _head, "sanity check"); 765 _head = data; 766 } 767 dead->set_next(_unloading); 768 _unloading = dead; 769 } 770 771 if (clean_alive) { 772 // Clean previous versions and the deallocate list. 773 ClassLoaderDataGraph::clean_metaspaces(); 774 } 775 776 if (seen_dead_loader) { 777 post_class_unload_events(); 778 } 779 780 return seen_dead_loader; 781 } 782 783 void ClassLoaderDataGraph::clean_metaspaces() { 784 // mark metadata seen on the stack and code cache so we can delete unneeded entries. 785 bool has_redefined_a_class = JvmtiExport::has_redefined_a_class(); 786 MetadataOnStackMark md_on_stack(has_redefined_a_class); 787 788 if (has_redefined_a_class) { 789 // purge_previous_versions also cleans weak method links. Because 790 // one method's MDO can reference another method from another 791 // class loader, we need to first clean weak method links for all 792 // class loaders here. Below, we can then free redefined methods 793 // for all class loaders. 794 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 795 data->classes_do(InstanceKlass::purge_previous_versions); 796 } 797 } 798 799 // Need to purge the previous version before deallocating. 800 free_deallocate_lists(); 801 } 802 803 void ClassLoaderDataGraph::purge() { 804 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 805 ClassLoaderData* list = _unloading; 806 _unloading = NULL; 807 ClassLoaderData* next = list; 808 bool classes_unloaded = false; 809 while (next != NULL) { 810 ClassLoaderData* purge_me = next; 811 next = purge_me->next(); 812 delete purge_me; 813 classes_unloaded = true; 814 } 815 if (classes_unloaded) { 816 Metaspace::purge(); 817 set_metaspace_oom(false); 818 } 819 } 820 821 void ClassLoaderDataGraph::post_class_unload_events(void) { 822 #if INCLUDE_TRACE 823 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 824 if (Tracing::enabled()) { 825 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) { 826 assert(_unloading != NULL, "need class loader data unload list!"); 827 _class_unload_time = Ticks::now(); 828 classes_unloading_do(&class_unload_event); 829 } 830 Tracing::on_unloading_classes(); 831 } 832 #endif 833 } 834 835 void ClassLoaderDataGraph::free_deallocate_lists() { 836 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 837 // We need to keep this data until InstanceKlass::purge_previous_version has been 838 // called on all alive classes. See the comment in ClassLoaderDataGraph::clean_metaspaces. 839 cld->free_deallocate_list(); 840 } 841 } 842 843 // CDS support 844 845 // Global metaspaces for writing information to the shared archive. When 846 // application CDS is supported, we may need one per metaspace, so this 847 // sort of looks like it. 848 Metaspace* ClassLoaderData::_ro_metaspace = NULL; 849 Metaspace* ClassLoaderData::_rw_metaspace = NULL; 850 static bool _shared_metaspaces_initialized = false; 851 852 // Initialize shared metaspaces (change to call from somewhere not lazily) 853 void ClassLoaderData::initialize_shared_metaspaces() { 854 assert(DumpSharedSpaces, "only use this for dumping shared spaces"); 855 assert(this == ClassLoaderData::the_null_class_loader_data(), 856 "only supported for null loader data for now"); 857 assert (!_shared_metaspaces_initialized, "only initialize once"); 858 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 859 _ro_metaspace = new Metaspace(_metaspace_lock, Metaspace::ROMetaspaceType); 860 _rw_metaspace = new Metaspace(_metaspace_lock, Metaspace::ReadWriteMetaspaceType); 861 _shared_metaspaces_initialized = true; 862 } 863 864 Metaspace* ClassLoaderData::ro_metaspace() { 865 assert(_ro_metaspace != NULL, "should already be initialized"); 866 return _ro_metaspace; 867 } 868 869 Metaspace* ClassLoaderData::rw_metaspace() { 870 assert(_rw_metaspace != NULL, "should already be initialized"); 871 return _rw_metaspace; 872 } 873 874 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic() 875 : _next_klass(NULL) { 876 ClassLoaderData* cld = ClassLoaderDataGraph::_head; 877 Klass* klass = NULL; 878 879 // Find the first klass in the CLDG. 880 while (cld != NULL) { 881 klass = cld->_klasses; 882 if (klass != NULL) { 883 _next_klass = klass; 884 return; 885 } 886 cld = cld->next(); 887 } 888 } 889 890 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) { 891 Klass* next = klass->next_link(); 892 if (next != NULL) { 893 return next; 894 } 895 896 // No more klasses in the current CLD. Time to find a new CLD. 897 ClassLoaderData* cld = klass->class_loader_data(); 898 while (next == NULL) { 899 cld = cld->next(); 900 if (cld == NULL) { 901 break; 902 } 903 next = cld->_klasses; 904 } 905 906 return next; 907 } 908 909 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() { 910 Klass* head = (Klass*)_next_klass; 911 912 while (head != NULL) { 913 Klass* next = next_klass_in_cldg(head); 914 915 Klass* old_head = (Klass*)Atomic::cmpxchg_ptr(next, &_next_klass, head); 916 917 if (old_head == head) { 918 return head; // Won the CAS. 919 } 920 921 head = old_head; 922 } 923 924 // Nothing more for the iterator to hand out. 925 assert(head == NULL, err_msg("head is " PTR_FORMAT ", expected not null:", p2i(head))); 926 return NULL; 927 } 928 929 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() { 930 _data = ClassLoaderDataGraph::_head; 931 } 932 933 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {} 934 935 #ifndef PRODUCT 936 // callable from debugger 937 extern "C" int print_loader_data_graph() { 938 ClassLoaderDataGraph::dump_on(tty); 939 return 0; 940 } 941 942 void ClassLoaderDataGraph::verify() { 943 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 944 data->verify(); 945 } 946 } 947 948 void ClassLoaderDataGraph::dump_on(outputStream * const out) { 949 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 950 data->dump(out); 951 } 952 MetaspaceAux::dump(out); 953 } 954 #endif // PRODUCT 955 956 void ClassLoaderData::print_value_on(outputStream* out) const { 957 if (class_loader() == NULL) { 958 out->print("NULL class_loader"); 959 } else { 960 out->print("class loader " INTPTR_FORMAT, p2i(this)); 961 class_loader()->print_value_on(out); 962 } 963 } 964 965 #if INCLUDE_TRACE 966 967 Ticks ClassLoaderDataGraph::_class_unload_time; 968 969 void ClassLoaderDataGraph::class_unload_event(Klass* const k) { 970 971 // post class unload event 972 EventClassUnload event(UNTIMED); 973 event.set_endtime(_class_unload_time); 974 event.set_unloadedClass(k); 975 oop defining_class_loader = k->class_loader(); 976 event.set_definingClassLoader(defining_class_loader != NULL ? 977 defining_class_loader->klass() : (Klass*)NULL); 978 event.commit(); 979 } 980 981 #endif // INCLUDE_TRACE