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 oop* _obj_ptr;
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 class PreserveObj;
68
69 public:
70 Allocation(const MemAllocator& allocator, oop* obj_ptr)
71 : _allocator(allocator),
72 _thread(Thread::current()),
73 _obj_ptr(obj_ptr),
74 _overhead_limit_exceeded(false),
75 _allocated_outside_tlab(false),
76 _allocated_tlab_size(0),
77 _tlab_end_reset_for_sample(false)
78 {
79 verify_before();
80 }
81
82 ~Allocation() {
83 if (!check_out_of_memory()) {
84 verify_after();
85 notify_allocation();
86 }
87 }
88
89 oop obj() const { return *_obj_ptr; }
90 };
91
92 class MemAllocator::Allocation::PreserveObj: StackObj {
93 HandleMark _handle_mark;
94 Handle _handle;
95 oop* const _obj_ptr;
96
97 public:
98 PreserveObj(Thread* thread, oop* obj_ptr)
99 : _handle_mark(thread),
100 _handle(thread, *obj_ptr),
101 _obj_ptr(obj_ptr)
102 {
103 *obj_ptr = NULL;
104 }
105
106 ~PreserveObj() {
107 *_obj_ptr = _handle();
108 }
109
110 oop operator()() const {
111 return _handle();
112 }
113 };
114
115 bool MemAllocator::Allocation::check_out_of_memory() {
116 Thread* THREAD = _thread;
117 assert(!HAS_PENDING_EXCEPTION, "Unexpected exception, will result in uninitialized storage");
118
119 if (obj() != NULL) {
120 return false;
121 }
122
123 const char* message = _overhead_limit_exceeded ? "GC overhead limit exceeded" : "Java heap space";
124 if (!THREAD->in_retryable_allocation()) {
125 // -XX:+HeapDumpOnOutOfMemoryError and -XX:OnOutOfMemoryError support
126 report_java_out_of_memory(message);
127
128 if (JvmtiExport::should_post_resource_exhausted()) {
129 JvmtiExport::post_resource_exhausted(
130 JVMTI_RESOURCE_EXHAUSTED_OOM_ERROR | JVMTI_RESOURCE_EXHAUSTED_JAVA_HEAP,
131 message);
132 }
133 oop exception = _overhead_limit_exceeded ?
134 Universe::out_of_memory_error_gc_overhead_limit() :
135 Universe::out_of_memory_error_java_heap();
136 THROW_OOP_(exception, true);
137 } else {
138 THROW_OOP_(Universe::out_of_memory_error_retry(), true);
139 }
140 }
141
142 void MemAllocator::Allocation::verify_before() {
143 // Clear unhandled oops for memory allocation. Memory allocation might
144 // not take out a lock if from tlab, so clear here.
145 Thread* THREAD = _thread;
146 CHECK_UNHANDLED_OOPS_ONLY(THREAD->clear_unhandled_oops();)
147 assert(!HAS_PENDING_EXCEPTION, "Should not allocate with exception pending");
148 debug_only(check_for_valid_allocation_state());
149 assert(!Universe::heap()->is_gc_active(), "Allocation during gc not allowed");
150 }
151
152 void MemAllocator::Allocation::verify_after() {
153 NOT_PRODUCT(check_for_bad_heap_word_value();)
154 }
155
156 void MemAllocator::Allocation::check_for_bad_heap_word_value() const {
157 MemRegion obj_range = _allocator.obj_memory_range(obj());
158 HeapWord* addr = obj_range.start();
159 size_t size = obj_range.word_size();
160 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
161 for (size_t slot = 0; slot < size; slot += 1) {
162 assert((*(intptr_t*) (addr + slot)) != ((intptr_t) badHeapWordVal),
163 "Found badHeapWordValue in post-allocation check");
164 }
165 }
166 }
167
168 #ifdef ASSERT
169 void MemAllocator::Allocation::check_for_valid_allocation_state() const {
170 // How to choose between a pending exception and a potential
171 // OutOfMemoryError? Don't allow pending exceptions.
172 // This is a VM policy failure, so how do we exhaustively test it?
173 assert(!_thread->has_pending_exception(),
174 "shouldn't be allocating with pending exception");
175 // Allocation of an oop can always invoke a safepoint,
176 // hence, the true argument.
177 _thread->check_for_valid_safepoint_state(true);
178 }
179 #endif
180
181 void MemAllocator::Allocation::notify_allocation_jvmti_sampler() {
182 // support for JVMTI VMObjectAlloc event (no-op if not enabled)
183 JvmtiExport::vm_object_alloc_event_collector(obj());
184
185 if (!JvmtiExport::should_post_sampled_object_alloc()) {
186 // Sampling disabled
187 return;
188 }
189
190 if (!_allocated_outside_tlab && _allocated_tlab_size == 0 && !_tlab_end_reset_for_sample) {
191 // Sample if it's a non-TLAB allocation, or a TLAB allocation that either refills the TLAB
192 // or expands it due to taking a sampler induced slow path.
193 return;
194 }
195
196 // If we want to be sampling, protect the allocated object with a Handle
197 // before doing the callback. The callback is done in the destructor of
198 // the JvmtiSampledObjectAllocEventCollector.
199 size_t bytes_since_last = 0;
200
201 {
202 PreserveObj obj_h(_thread, _obj_ptr);
203 JvmtiSampledObjectAllocEventCollector collector;
204 size_t size_in_bytes = _allocator._word_size * HeapWordSize;
205 ThreadLocalAllocBuffer& tlab = _thread->tlab();
206
207 if (!_allocated_outside_tlab) {
208 bytes_since_last = tlab.bytes_since_last_sample_point();
209 }
210
211 _thread->heap_sampler().check_for_sampling(obj_h(), size_in_bytes, bytes_since_last);
212 }
213
214 if (_tlab_end_reset_for_sample || _allocated_tlab_size != 0) {
215 // Tell tlab to forget bytes_since_last if we passed it to the heap sampler.
216 _thread->tlab().set_sample_end(bytes_since_last != 0);
217 }
218 }
219
220 void MemAllocator::Allocation::notify_allocation_low_memory_detector() {
221 // support low memory notifications (no-op if not enabled)
222 LowMemoryDetector::detect_low_memory_for_collected_pools();
223 }
224
225 void MemAllocator::Allocation::notify_allocation_jfr_sampler() {
226 HeapWord* mem = (HeapWord*)obj();
227 size_t size_in_bytes = _allocator._word_size * HeapWordSize;
228
229 if (_allocated_outside_tlab) {
230 AllocTracer::send_allocation_outside_tlab(_allocator._klass, mem, size_in_bytes, _thread);
231 } else if (_allocated_tlab_size != 0) {
232 // TLAB was refilled
233 AllocTracer::send_allocation_in_new_tlab(_allocator._klass, mem, _allocated_tlab_size * HeapWordSize,
234 size_in_bytes, _thread);
235 }
236 }
237
238 void MemAllocator::Allocation::notify_allocation_dtrace_sampler() {
239 if (DTraceAllocProbes) {
240 // support for Dtrace object alloc event (no-op most of the time)
241 Klass* klass = _allocator._klass;
242 size_t word_size = _allocator._word_size;
243 if (klass != NULL && klass->name() != NULL) {
244 SharedRuntime::dtrace_object_alloc(obj(), (int)word_size);
245 }
246 }
247 }
248
249 void MemAllocator::Allocation::notify_allocation() {
250 notify_allocation_low_memory_detector();
251 notify_allocation_jfr_sampler();
252 notify_allocation_dtrace_sampler();
253 notify_allocation_jvmti_sampler();
254 }
255
256 HeapWord* MemAllocator::allocate_outside_tlab(Allocation& allocation) const {
257 allocation._allocated_outside_tlab = true;
258 HeapWord* mem = Universe::heap()->mem_allocate(_word_size, &allocation._overhead_limit_exceeded);
259 if (mem == NULL) {
260 return mem;
261 }
262
263 NOT_PRODUCT(Universe::heap()->check_for_non_bad_heap_word_value(mem, _word_size));
264 size_t size_in_bytes = _word_size * HeapWordSize;
265 _thread->incr_allocated_bytes(size_in_bytes);
266
267 return mem;
268 }
269
270 HeapWord* MemAllocator::allocate_inside_tlab(Allocation& allocation) const {
271 assert(UseTLAB, "should use UseTLAB");
272
273 // Try allocating from an existing TLAB.
274 HeapWord* mem = _thread->tlab().allocate(_word_size);
275 if (mem != NULL) {
276 return mem;
277 }
278
279 // Try refilling the TLAB and allocating the object in it.
280 return allocate_inside_tlab_slow(allocation);
281 }
282
283 HeapWord* MemAllocator::allocate_inside_tlab_slow(Allocation& allocation) const {
284 HeapWord* mem = NULL;
285 ThreadLocalAllocBuffer& tlab = _thread->tlab();
286
287 if (JvmtiExport::should_post_sampled_object_alloc()) {
288 tlab.set_back_allocation_end();
289 mem = tlab.allocate(_word_size);
290
291 // We set back the allocation sample point to try to allocate this, reset it
292 // when done.
293 allocation._tlab_end_reset_for_sample = true;
294
295 if (mem != NULL) {
296 return mem;
297 }
298 }
299
300 // Retain tlab and allocate object in shared space if
301 // the amount free in the tlab is too large to discard.
302 if (tlab.free() > tlab.refill_waste_limit()) {
303 tlab.record_slow_allocation(_word_size);
304 return NULL;
305 }
306
307 // Discard tlab and allocate a new one.
308 // To minimize fragmentation, the last TLAB may be smaller than the rest.
309 size_t new_tlab_size = tlab.compute_size(_word_size);
310
311 tlab.retire_before_allocation();
312
313 if (new_tlab_size == 0) {
314 return NULL;
315 }
316
317 // Allocate a new TLAB requesting new_tlab_size. Any size
318 // between minimal and new_tlab_size is accepted.
319 size_t min_tlab_size = ThreadLocalAllocBuffer::compute_min_size(_word_size);
320 mem = Universe::heap()->allocate_new_tlab(min_tlab_size, new_tlab_size, &allocation._allocated_tlab_size);
321 if (mem == NULL) {
322 assert(allocation._allocated_tlab_size == 0,
323 "Allocation failed, but actual size was updated. min: " SIZE_FORMAT
324 ", desired: " SIZE_FORMAT ", actual: " SIZE_FORMAT,
325 min_tlab_size, new_tlab_size, allocation._allocated_tlab_size);
326 return NULL;
327 }
328 assert(allocation._allocated_tlab_size != 0, "Allocation succeeded but actual size not updated. mem at: "
329 PTR_FORMAT " min: " SIZE_FORMAT ", desired: " SIZE_FORMAT,
330 p2i(mem), min_tlab_size, new_tlab_size);
331
332 if (ZeroTLAB) {
333 // ..and clear it.
334 Copy::zero_to_words(mem, allocation._allocated_tlab_size);
335 } else {
336 // ...and zap just allocated object.
337 #ifdef ASSERT
338 // Skip mangling the space corresponding to the object header to
339 // ensure that the returned space is not considered parsable by
340 // any concurrent GC thread.
341 size_t hdr_size = oopDesc::header_size();
342 Copy::fill_to_words(mem + hdr_size, allocation._allocated_tlab_size - hdr_size, badHeapWordVal);
343 #endif // ASSERT
344 }
345
346 tlab.fill(mem, mem + _word_size, allocation._allocated_tlab_size);
347 return mem;
348 }
349
350 HeapWord* MemAllocator::mem_allocate(Allocation& allocation) const {
351 if (UseTLAB) {
352 HeapWord* result = allocate_inside_tlab(allocation);
353 if (result != NULL) {
354 return result;
355 }
356 }
357
358 return allocate_outside_tlab(allocation);
359 }
360
361 oop MemAllocator::allocate() const {
362 oop obj = NULL;
363 {
364 Allocation allocation(*this, &obj);
365 HeapWord* mem = mem_allocate(allocation);
366 if (mem != NULL) {
367 obj = initialize(mem);
368 } else {
369 // The unhandled oop detector will poison local variable obj,
370 // so reset it to NULL if mem is NULL.
371 obj = NULL;
372 }
373 }
374 return obj;
375 }
376
377 void MemAllocator::mem_clear(HeapWord* mem) const {
378 assert(mem != NULL, "cannot initialize NULL object");
379 const size_t hs = oopDesc::header_size();
380 assert(_word_size >= hs, "unexpected object size");
381 oopDesc::set_klass_gap(mem, 0);
382 Copy::fill_to_aligned_words(mem + hs, _word_size - hs);
383 }
384
385 oop MemAllocator::finish(HeapWord* mem) const {
386 assert(mem != NULL, "NULL object pointer");
387 if (UseBiasedLocking) {
388 oopDesc::set_mark_raw(mem, _klass->prototype_header());
389 } else {
390 // May be bootstrapping
391 oopDesc::set_mark_raw(mem, markOopDesc::prototype());
392 }
393 // Need a release store to ensure array/class length, mark word, and
394 // object zeroing are visible before setting the klass non-NULL, for
395 // concurrent collectors.
396 oopDesc::release_set_klass(mem, _klass);
397 return oop(mem);
398 }
399
400 oop ObjAllocator::initialize(HeapWord* mem) const {
401 mem_clear(mem);
402 return finish(mem);
403 }
404
405 MemRegion ObjArrayAllocator::obj_memory_range(oop obj) const {
406 if (_do_zero) {
407 return MemAllocator::obj_memory_range(obj);
408 }
409 ArrayKlass* array_klass = ArrayKlass::cast(_klass);
410 const size_t hs = arrayOopDesc::header_size(array_klass->element_type());
411 return MemRegion(((HeapWord*)obj) + hs, _word_size - hs);
412 }
413
414 oop ObjArrayAllocator::initialize(HeapWord* mem) const {
415 // Set array length before setting the _klass field because a
416 // non-NULL klass field indicates that the object is parsable by
417 // concurrent GC.
418 assert(_length >= 0, "length should be non-negative");
419 if (_do_zero) {
420 mem_clear(mem);
421 }
422 arrayOopDesc::set_length(mem, _length);
423 return finish(mem);
424 }
425
426 oop ClassAllocator::initialize(HeapWord* mem) const {
427 // Set oop_size field before setting the _klass field because a
428 // non-NULL _klass field indicates that the object is parsable by
429 // concurrent GC.
430 assert(_word_size > 0, "oop_size must be positive.");
431 mem_clear(mem);
432 java_lang_Class::set_oop_size(mem, (int)_word_size);
433 return finish(mem);
434 }