1 /* 2 * Copyright (c) 2018, 2019, 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 #include "precompiled.hpp" 26 #include "classfile/javaClasses.hpp" 27 #include "gc/shared/allocTracer.hpp" 28 #include "gc/shared/collectedHeap.hpp" 29 #include "gc/shared/memAllocator.hpp" 30 #include "gc/shared/threadLocalAllocBuffer.inline.hpp" 31 #include "memory/universe.hpp" 32 #include "oops/arrayOop.hpp" 33 #include "oops/oop.inline.hpp" 34 #include "prims/jvmtiExport.hpp" 35 #include "runtime/sharedRuntime.hpp" 36 #include "runtime/handles.inline.hpp" 37 #include "runtime/thread.inline.hpp" 38 #include "services/lowMemoryDetector.hpp" 39 #include "utilities/align.hpp" 40 #include "utilities/copy.hpp" 41 42 class MemAllocator::Allocation: StackObj { 43 friend class MemAllocator; 44 45 const MemAllocator& _allocator; 46 Thread* _thread; 47 Handle _handle; 48 bool _overhead_limit_exceeded; 49 bool _allocated_outside_tlab; 50 size_t _allocated_tlab_size; 51 bool _tlab_end_reset_for_sample; 52 53 bool check_out_of_memory(); 54 void verify_before(); 55 void verify_after(); 56 void notify_allocation(); 57 void notify_allocation_jvmti_allocation_event(); 58 void notify_allocation_jvmti_sampler(); 59 void notify_allocation_low_memory_detector(); 60 void notify_allocation_jfr_sampler(); 61 void notify_allocation_dtrace_sampler(); 62 void check_for_bad_heap_word_value() const; 63 #ifdef ASSERT 64 void check_for_valid_allocation_state() const; 65 #endif 66 67 public: 68 Allocation(const MemAllocator& allocator) 69 : _allocator(allocator), 70 _thread(Thread::current()), 71 _overhead_limit_exceeded(false), 72 _allocated_outside_tlab(false), 73 _allocated_tlab_size(0), 74 _tlab_end_reset_for_sample(false) 75 { 76 verify_before(); 77 } 78 79 ~Allocation() { 80 if (!check_out_of_memory()) { 81 verify_after(); 82 notify_allocation(); 83 } 84 } 85 86 void set_obj(oop obj) { _handle = Handle(_thread, obj); } 87 oop obj() const { return _handle(); } 88 }; 89 90 bool MemAllocator::Allocation::check_out_of_memory() { 91 Thread* THREAD = _thread; 92 assert(!HAS_PENDING_EXCEPTION, "Unexpected exception, will result in uninitialized storage"); 93 94 if (obj() != NULL) { 95 return false; 96 } 97 98 const char* message = _overhead_limit_exceeded ? "GC overhead limit exceeded" : "Java heap space"; 99 if (!THREAD->in_retryable_allocation()) { 100 // -XX:+HeapDumpOnOutOfMemoryError and -XX:OnOutOfMemoryError support 101 report_java_out_of_memory(message); 102 103 if (JvmtiExport::should_post_resource_exhausted()) { 104 JvmtiExport::post_resource_exhausted( 105 JVMTI_RESOURCE_EXHAUSTED_OOM_ERROR | JVMTI_RESOURCE_EXHAUSTED_JAVA_HEAP, 106 message); 107 } 108 oop exception = _overhead_limit_exceeded ? 109 Universe::out_of_memory_error_gc_overhead_limit() : 110 Universe::out_of_memory_error_java_heap(); 111 THROW_OOP_(exception, true); 112 } else { 113 THROW_OOP_(Universe::out_of_memory_error_retry(), true); 114 } 115 } 116 117 void MemAllocator::Allocation::verify_before() { 118 // Clear unhandled oops for memory allocation. Memory allocation might 119 // not take out a lock if from tlab, so clear here. 120 Thread* THREAD = _thread; 121 CHECK_UNHANDLED_OOPS_ONLY(THREAD->clear_unhandled_oops();) 122 assert(!HAS_PENDING_EXCEPTION, "Should not allocate with exception pending"); 123 debug_only(check_for_valid_allocation_state()); 124 assert(!Universe::heap()->is_gc_active(), "Allocation during gc not allowed"); 125 } 126 127 void MemAllocator::Allocation::verify_after() { 128 NOT_PRODUCT(check_for_bad_heap_word_value();) 129 } 130 131 void MemAllocator::Allocation::check_for_bad_heap_word_value() const { 132 MemRegion obj_range = _allocator.obj_memory_range(obj()); 133 HeapWord* addr = obj_range.start(); 134 size_t size = obj_range.word_size(); 135 if (CheckMemoryInitialization && ZapUnusedHeapArea) { 136 for (size_t slot = 0; slot < size; slot += 1) { 137 assert((*(intptr_t*) (addr + slot)) != ((intptr_t) badHeapWordVal), 138 "Found badHeapWordValue in post-allocation check"); 139 } 140 } 141 } 142 143 #ifdef ASSERT 144 void MemAllocator::Allocation::check_for_valid_allocation_state() const { 145 // How to choose between a pending exception and a potential 146 // OutOfMemoryError? Don't allow pending exceptions. 147 // This is a VM policy failure, so how do we exhaustively test it? 148 assert(!_thread->has_pending_exception(), 149 "shouldn't be allocating with pending exception"); 150 if (StrictSafepointChecks) { 151 assert(_thread->allow_allocation(), 152 "Allocation done by thread for which allocation is blocked " 153 "by No_Allocation_Verifier!"); 154 // Allocation of an oop can always invoke a safepoint, 155 // hence, the true argument 156 _thread->check_for_valid_safepoint_state(true); 157 } 158 } 159 #endif 160 161 void MemAllocator::Allocation::notify_allocation_jvmti_sampler() { 162 // support for JVMTI VMObjectAlloc event (no-op if not enabled) 163 JvmtiExport::vm_object_alloc_event_collector(obj()); 164 165 if (!JvmtiExport::should_post_sampled_object_alloc()) { 166 // Sampling disabled 167 return; 168 } 169 170 if (!_allocated_outside_tlab && _allocated_tlab_size == 0 && !_tlab_end_reset_for_sample) { 171 // Sample if it's a non-TLAB allocation, or a TLAB allocation that either refills the TLAB 172 // or expands it due to taking a sampler induced slow path. 173 return; 174 } 175 176 // If we want to be sampling, the allocated object is protected with a Handle 177 // before doing the callback. The callback is done in the destructor of 178 // the JvmtiSampledObjectAllocEventCollector. 179 size_t bytes_since_last = 0; 180 181 { 182 JvmtiSampledObjectAllocEventCollector collector; 183 size_t size_in_bytes = _allocator._word_size * HeapWordSize; 184 ThreadLocalAllocBuffer& tlab = _thread->tlab(); 185 186 if (!_allocated_outside_tlab) { 187 bytes_since_last = tlab.bytes_since_last_sample_point(); 188 } 189 190 _thread->heap_sampler().check_for_sampling(obj(), size_in_bytes, bytes_since_last); 191 } 192 193 if (_tlab_end_reset_for_sample || _allocated_tlab_size != 0) { 194 // Tell tlab to forget bytes_since_last if we passed it to the heap sampler. 195 _thread->tlab().set_sample_end(bytes_since_last != 0); 196 } 197 } 198 199 void MemAllocator::Allocation::notify_allocation_low_memory_detector() { 200 // support low memory notifications (no-op if not enabled) 201 LowMemoryDetector::detect_low_memory_for_collected_pools(); 202 } 203 204 void MemAllocator::Allocation::notify_allocation_jfr_sampler() { 205 HeapWord* mem = (HeapWord*)obj(); 206 size_t size_in_bytes = _allocator._word_size * HeapWordSize; 207 208 if (_allocated_outside_tlab) { 209 AllocTracer::send_allocation_outside_tlab(_allocator._klass, mem, size_in_bytes, _thread); 210 } else if (_allocated_tlab_size != 0) { 211 // TLAB was refilled 212 AllocTracer::send_allocation_in_new_tlab(_allocator._klass, mem, _allocated_tlab_size * HeapWordSize, 213 size_in_bytes, _thread); 214 } 215 } 216 217 void MemAllocator::Allocation::notify_allocation_dtrace_sampler() { 218 if (DTraceAllocProbes) { 219 // support for Dtrace object alloc event (no-op most of the time) 220 Klass* klass = _allocator._klass; 221 size_t word_size = _allocator._word_size; 222 if (klass != NULL && klass->name() != NULL) { 223 SharedRuntime::dtrace_object_alloc(obj(), (int)word_size); 224 } 225 } 226 } 227 228 void MemAllocator::Allocation::notify_allocation() { 229 notify_allocation_low_memory_detector(); 230 notify_allocation_jfr_sampler(); 231 notify_allocation_dtrace_sampler(); 232 notify_allocation_jvmti_sampler(); 233 } 234 235 HeapWord* MemAllocator::allocate_outside_tlab(Allocation& allocation) const { 236 allocation._allocated_outside_tlab = true; 237 HeapWord* mem = Universe::heap()->mem_allocate(_word_size, &allocation._overhead_limit_exceeded); 238 if (mem == NULL) { 239 return mem; 240 } 241 242 NOT_PRODUCT(Universe::heap()->check_for_non_bad_heap_word_value(mem, _word_size)); 243 size_t size_in_bytes = _word_size * HeapWordSize; 244 _thread->incr_allocated_bytes(size_in_bytes); 245 246 return mem; 247 } 248 249 HeapWord* MemAllocator::allocate_inside_tlab(Allocation& allocation) const { 250 assert(UseTLAB, "should use UseTLAB"); 251 252 // Try allocating from an existing TLAB. 253 HeapWord* mem = _thread->tlab().allocate(_word_size); 254 if (mem != NULL) { 255 return mem; 256 } 257 258 // Try refilling the TLAB and allocating the object in it. 259 return allocate_inside_tlab_slow(allocation); 260 } 261 262 HeapWord* MemAllocator::allocate_inside_tlab_slow(Allocation& allocation) const { 263 HeapWord* mem = NULL; 264 ThreadLocalAllocBuffer& tlab = _thread->tlab(); 265 266 if (JvmtiExport::should_post_sampled_object_alloc()) { 267 tlab.set_back_allocation_end(); 268 mem = tlab.allocate(_word_size); 269 270 // We set back the allocation sample point to try to allocate this, reset it 271 // when done. 272 allocation._tlab_end_reset_for_sample = true; 273 274 if (mem != NULL) { 275 return mem; 276 } 277 } 278 279 // Retain tlab and allocate object in shared space if 280 // the amount free in the tlab is too large to discard. 281 if (tlab.free() > tlab.refill_waste_limit()) { 282 tlab.record_slow_allocation(_word_size); 283 return NULL; 284 } 285 286 // Discard tlab and allocate a new one. 287 // To minimize fragmentation, the last TLAB may be smaller than the rest. 288 size_t new_tlab_size = tlab.compute_size(_word_size); 289 290 tlab.retire_before_allocation(); 291 292 if (new_tlab_size == 0) { 293 return NULL; 294 } 295 296 // Allocate a new TLAB requesting new_tlab_size. Any size 297 // between minimal and new_tlab_size is accepted. 298 size_t min_tlab_size = ThreadLocalAllocBuffer::compute_min_size(_word_size); 299 mem = Universe::heap()->allocate_new_tlab(min_tlab_size, new_tlab_size, &allocation._allocated_tlab_size); 300 if (mem == NULL) { 301 assert(allocation._allocated_tlab_size == 0, 302 "Allocation failed, but actual size was updated. min: " SIZE_FORMAT 303 ", desired: " SIZE_FORMAT ", actual: " SIZE_FORMAT, 304 min_tlab_size, new_tlab_size, allocation._allocated_tlab_size); 305 return NULL; 306 } 307 assert(allocation._allocated_tlab_size != 0, "Allocation succeeded but actual size not updated. mem at: " 308 PTR_FORMAT " min: " SIZE_FORMAT ", desired: " SIZE_FORMAT, 309 p2i(mem), min_tlab_size, new_tlab_size); 310 311 if (ZeroTLAB) { 312 // ..and clear it. 313 Copy::zero_to_words(mem, allocation._allocated_tlab_size); 314 } else { 315 // ...and zap just allocated object. 316 #ifdef ASSERT 317 // Skip mangling the space corresponding to the object header to 318 // ensure that the returned space is not considered parsable by 319 // any concurrent GC thread. 320 size_t hdr_size = oopDesc::header_size(); 321 Copy::fill_to_words(mem + hdr_size, allocation._allocated_tlab_size - hdr_size, badHeapWordVal); 322 #endif // ASSERT 323 } 324 325 tlab.fill(mem, mem + _word_size, allocation._allocated_tlab_size); 326 return mem; 327 } 328 329 HeapWord* MemAllocator::mem_allocate(Allocation& allocation) const { 330 if (UseTLAB) { 331 HeapWord* result = allocate_inside_tlab(allocation); 332 if (result != NULL) { 333 return result; 334 } 335 } 336 337 return allocate_outside_tlab(allocation); 338 } 339 340 oop MemAllocator::allocate() const { 341 HandleMark hm(_thread); 342 Handle obj_h; 343 { 344 Allocation allocation(*this); 345 HeapWord* mem = mem_allocate(allocation); 346 if (mem != NULL) { 347 oop obj = initialize(mem); 348 // Save obj in a handle for destructor safepoints 349 allocation.set_obj(obj); 350 obj_h = Handle(_thread, obj); 351 } 352 } 353 return obj_h(); 354 } 355 356 void MemAllocator::mem_clear(HeapWord* mem) const { 357 assert(mem != NULL, "cannot initialize NULL object"); 358 const size_t hs = oopDesc::header_size(); 359 assert(_word_size >= hs, "unexpected object size"); 360 oopDesc::set_klass_gap(mem, 0); 361 Copy::fill_to_aligned_words(mem + hs, _word_size - hs); 362 } 363 364 oop MemAllocator::finish(HeapWord* mem) const { 365 assert(mem != NULL, "NULL object pointer"); 366 if (UseBiasedLocking) { 367 oopDesc::set_mark_raw(mem, _klass->prototype_header()); 368 } else { 369 // May be bootstrapping 370 oopDesc::set_mark_raw(mem, markOopDesc::prototype()); 371 } 372 // Need a release store to ensure array/class length, mark word, and 373 // object zeroing are visible before setting the klass non-NULL, for 374 // concurrent collectors. 375 oopDesc::release_set_klass(mem, _klass); 376 return oop(mem); 377 } 378 379 oop ObjAllocator::initialize(HeapWord* mem) const { 380 mem_clear(mem); 381 return finish(mem); 382 } 383 384 MemRegion ObjArrayAllocator::obj_memory_range(oop obj) const { 385 if (_do_zero) { 386 return MemAllocator::obj_memory_range(obj); 387 } 388 ArrayKlass* array_klass = ArrayKlass::cast(_klass); 389 const size_t hs = arrayOopDesc::header_size(array_klass->element_type()); 390 return MemRegion(((HeapWord*)obj) + hs, _word_size - hs); 391 } 392 393 oop ObjArrayAllocator::initialize(HeapWord* mem) const { 394 // Set array length before setting the _klass field because a 395 // non-NULL klass field indicates that the object is parsable by 396 // concurrent GC. 397 assert(_length >= 0, "length should be non-negative"); 398 if (_do_zero) { 399 mem_clear(mem); 400 } 401 arrayOopDesc::set_length(mem, _length); 402 return finish(mem); 403 } 404 405 oop ClassAllocator::initialize(HeapWord* mem) const { 406 // Set oop_size field before setting the _klass field because a 407 // non-NULL _klass field indicates that the object is parsable by 408 // concurrent GC. 409 assert(_word_size > 0, "oop_size must be positive."); 410 mem_clear(mem); 411 java_lang_Class::set_oop_size(mem, (int)_word_size); 412 return finish(mem); 413 }