1 /* 2 * Copyright (c) 2016, 2018, Red Hat, Inc. All rights reserved. 3 * 4 * This code is free software; you can redistribute it and/or modify it 5 * under the terms of the GNU General Public License version 2 only, as 6 * published by the Free Software Foundation. 7 * 8 * This code is distributed in the hope that it will be useful, but WITHOUT 9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 11 * version 2 for more details (a copy is included in the LICENSE file that 12 * accompanied this code). 13 * 14 * You should have received a copy of the GNU General Public License version 15 * 2 along with this work; if not, write to the Free Software Foundation, 16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 17 * 18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 19 * or visit www.oracle.com if you need additional information or have any 20 * questions. 21 * 22 */ 23 24 #include "precompiled.hpp" 25 26 #include "gc/shenandoah/shenandoahFreeSet.hpp" 27 #include "gc/shenandoah/shenandoahHeap.inline.hpp" 28 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp" 29 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp" 30 #include "gc/shenandoah/shenandoahTraversalGC.hpp" 31 #include "logging/logStream.hpp" 32 33 ShenandoahFreeSet::ShenandoahFreeSet(ShenandoahHeap* heap, size_t max_regions) : 34 _heap(heap), 35 _mutator_free_bitmap(max_regions, mtGC), 36 _collector_free_bitmap(max_regions, mtGC), 37 _max(max_regions) 38 { 39 clear_internal(); 40 } 41 42 void ShenandoahFreeSet::increase_used(size_t num_bytes) { 43 assert_heaplock_owned_by_current_thread(); 44 _used += num_bytes; 45 46 assert(_used <= _capacity, "must not use more than we have: used: " SIZE_FORMAT 47 ", capacity: " SIZE_FORMAT ", num_bytes: " SIZE_FORMAT, _used, _capacity, num_bytes); 48 } 49 50 bool ShenandoahFreeSet::is_mutator_free(size_t idx) const { 51 assert (idx < _max, "index is sane: " SIZE_FORMAT " < " SIZE_FORMAT " (left: " SIZE_FORMAT ", right: " SIZE_FORMAT ")", 52 idx, _max, _mutator_leftmost, _mutator_rightmost); 53 return _mutator_free_bitmap.at(idx); 54 } 55 56 bool ShenandoahFreeSet::is_collector_free(size_t idx) const { 57 assert (idx < _max, "index is sane: " SIZE_FORMAT " < " SIZE_FORMAT " (left: " SIZE_FORMAT ", right: " SIZE_FORMAT ")", 58 idx, _max, _collector_leftmost, _collector_rightmost); 59 return _collector_free_bitmap.at(idx); 60 } 61 62 HeapWord* ShenandoahFreeSet::allocate_single(ShenandoahAllocRequest& req, bool& in_new_region) { 63 // Scan the bitmap looking for a first fit. 64 // 65 // Leftmost and rightmost bounds provide enough caching to walk bitmap efficiently. Normally, 66 // we would find the region to allocate at right away. 67 // 68 // Allocations are biased: new application allocs go to beginning of the heap, and GC allocs 69 // go to the end. This makes application allocation faster, because we would clear lots 70 // of regions from the beginning most of the time. 71 // 72 // Free set maintains mutator and collector views, and normally they allocate in their views only, 73 // unless we special cases for stealing and mixed allocations. 74 75 switch (req.type()) { 76 case ShenandoahAllocRequest::_alloc_tlab: 77 case ShenandoahAllocRequest::_alloc_shared: { 78 79 // Try to allocate in the mutator view 80 for (size_t idx = _mutator_leftmost; idx <= _mutator_rightmost; idx++) { 81 if (is_mutator_free(idx)) { 82 HeapWord* result = try_allocate_in(_heap->get_region(idx), req, in_new_region); 83 if (result != NULL) { 84 return result; 85 } 86 } 87 } 88 89 // There is no recovery. Mutator does not touch collector view at all. 90 break; 91 } 92 case ShenandoahAllocRequest::_alloc_gclab: 93 case ShenandoahAllocRequest::_alloc_shared_gc: { 94 // size_t is unsigned, need to dodge underflow when _leftmost = 0 95 96 // Fast-path: try to allocate in the collector view first 97 for (size_t c = _collector_rightmost + 1; c > _collector_leftmost; c--) { 98 size_t idx = c - 1; 99 if (is_collector_free(idx)) { 100 HeapWord* result = try_allocate_in(_heap->get_region(idx), req, in_new_region); 101 if (result != NULL) { 102 return result; 103 } 104 } 105 } 106 107 // No dice. Can we borrow space from mutator view? 108 if (!ShenandoahEvacReserveOverflow) { 109 return NULL; 110 } 111 112 // Try to steal the empty region from the mutator view 113 for (size_t c = _mutator_rightmost + 1; c > _mutator_leftmost; c--) { 114 size_t idx = c - 1; 115 if (is_mutator_free(idx)) { 116 ShenandoahHeapRegion* r = _heap->get_region(idx); 117 if (is_empty_or_trash(r)) { 118 flip_to_gc(r); 119 HeapWord *result = try_allocate_in(r, req, in_new_region); 120 if (result != NULL) { 121 return result; 122 } 123 } 124 } 125 } 126 127 // Try to mix the allocation into the mutator view: 128 if (ShenandoahAllowMixedAllocs) { 129 for (size_t c = _mutator_rightmost + 1; c > _mutator_leftmost; c--) { 130 size_t idx = c - 1; 131 if (is_mutator_free(idx)) { 132 HeapWord* result = try_allocate_in(_heap->get_region(idx), req, in_new_region); 133 if (result != NULL) { 134 return result; 135 } 136 } 137 } 138 } 139 break; 140 } 141 default: 142 ShouldNotReachHere(); 143 } 144 145 return NULL; 146 } 147 148 HeapWord* ShenandoahFreeSet::try_allocate_in(ShenandoahHeapRegion* r, ShenandoahAllocRequest& req, bool& in_new_region) { 149 assert (!has_no_alloc_capacity(r), "Performance: should avoid full regions on this path: " SIZE_FORMAT, r->region_number()); 150 151 try_recycle_trashed(r); 152 153 in_new_region = r->is_empty(); 154 155 HeapWord* result = NULL; 156 size_t size = req.size(); 157 158 if (ShenandoahElasticTLAB && req.is_lab_alloc()) { 159 size_t free = align_down(r->free() >> LogHeapWordSize, MinObjAlignment); 160 if (size > free) { 161 size = free; 162 } 163 if (size >= req.min_size()) { 164 result = r->allocate(size, req.type()); 165 assert (result != NULL, "Allocation must succeed: free " SIZE_FORMAT ", actual " SIZE_FORMAT, free, size); 166 } 167 } else { 168 result = r->allocate(size, req.type()); 169 } 170 171 if (result != NULL) { 172 // Allocation successful, bump stats: 173 if (req.is_mutator_alloc()) { 174 increase_used(size * HeapWordSize); 175 } 176 177 // Record actual allocation size 178 req.set_actual_size(size); 179 180 if (req.is_gc_alloc() && _heap->is_concurrent_traversal_in_progress()) { 181 // Traversal needs to traverse through GC allocs. Adjust TAMS to the new top 182 // so that these allocations appear below TAMS, and thus get traversed. 183 // See top of shenandoahTraversal.cpp for an explanation. 184 _heap->marking_context()->capture_top_at_mark_start(r); 185 _heap->traversal_gc()->traversal_set()->add_region_check_for_duplicates(r); 186 OrderAccess::fence(); 187 } 188 } 189 190 if (result == NULL || has_no_alloc_capacity(r)) { 191 // Region cannot afford this or future allocations. Retire it. 192 // 193 // While this seems a bit harsh, especially in the case when this large allocation does not 194 // fit, but the next small one would, we are risking to inflate scan times when lots of 195 // almost-full regions precede the fully-empty region where we want allocate the entire TLAB. 196 // TODO: Record first fully-empty region, and use that for large allocations 197 198 // Record the remainder as allocation waste 199 if (req.is_mutator_alloc()) { 200 size_t waste = r->free(); 201 if (waste > 0) { 202 increase_used(waste); 203 _heap->notify_mutator_alloc_words(waste >> LogHeapWordSize, true); 204 } 205 } 206 207 size_t num = r->region_number(); 208 _collector_free_bitmap.clear_bit(num); 209 _mutator_free_bitmap.clear_bit(num); 210 // Touched the bounds? Need to update: 211 if (touches_bounds(num)) { 212 adjust_bounds(); 213 } 214 assert_bounds(); 215 } 216 return result; 217 } 218 219 bool ShenandoahFreeSet::touches_bounds(size_t num) const { 220 return num == _collector_leftmost || num == _collector_rightmost || num == _mutator_leftmost || num == _mutator_rightmost; 221 } 222 223 void ShenandoahFreeSet::recompute_bounds() { 224 // Reset to the most pessimistic case: 225 _mutator_rightmost = _max - 1; 226 _mutator_leftmost = 0; 227 _collector_rightmost = _max - 1; 228 _collector_leftmost = 0; 229 230 // ...and adjust from there 231 adjust_bounds(); 232 } 233 234 void ShenandoahFreeSet::adjust_bounds() { 235 // Rewind both mutator bounds until the next bit. 236 while (_mutator_leftmost < _max && !is_mutator_free(_mutator_leftmost)) { 237 _mutator_leftmost++; 238 } 239 while (_mutator_rightmost > 0 && !is_mutator_free(_mutator_rightmost)) { 240 _mutator_rightmost--; 241 } 242 // Rewind both collector bounds until the next bit. 243 while (_collector_leftmost < _max && !is_collector_free(_collector_leftmost)) { 244 _collector_leftmost++; 245 } 246 while (_collector_rightmost > 0 && !is_collector_free(_collector_rightmost)) { 247 _collector_rightmost--; 248 } 249 } 250 251 HeapWord* ShenandoahFreeSet::allocate_contiguous(ShenandoahAllocRequest& req) { 252 assert_heaplock_owned_by_current_thread(); 253 254 size_t words_size = req.size(); 255 size_t num = ShenandoahHeapRegion::required_regions(words_size * HeapWordSize); 256 257 // No regions left to satisfy allocation, bye. 258 if (num > mutator_count()) { 259 return NULL; 260 } 261 262 // Find the continuous interval of $num regions, starting from $beg and ending in $end, 263 // inclusive. Contiguous allocations are biased to the beginning. 264 265 size_t beg = _mutator_leftmost; 266 size_t end = beg; 267 268 while (true) { 269 if (end >= _max) { 270 // Hit the end, goodbye 271 return NULL; 272 } 273 274 // If regions are not adjacent, then current [beg; end] is useless, and we may fast-forward. 275 // If region is not completely free, the current [beg; end] is useless, and we may fast-forward. 276 if (!is_mutator_free(end) || !is_empty_or_trash(_heap->get_region(end))) { 277 end++; 278 beg = end; 279 continue; 280 } 281 282 if ((end - beg + 1) == num) { 283 // found the match 284 break; 285 } 286 287 end++; 288 }; 289 290 size_t remainder = words_size & ShenandoahHeapRegion::region_size_words_mask(); 291 292 // Initialize regions: 293 for (size_t i = beg; i <= end; i++) { 294 ShenandoahHeapRegion* r = _heap->get_region(i); 295 try_recycle_trashed(r); 296 297 assert(i == beg || _heap->get_region(i-1)->region_number() + 1 == r->region_number(), "Should be contiguous"); 298 assert(r->is_empty(), "Should be empty"); 299 300 if (i == beg) { 301 r->make_humongous_start(); 302 } else { 303 r->make_humongous_cont(); 304 } 305 306 // Trailing region may be non-full, record the remainder there 307 size_t used_words; 308 if ((i == end) && (remainder != 0)) { 309 used_words = remainder; 310 } else { 311 used_words = ShenandoahHeapRegion::region_size_words(); 312 } 313 314 r->set_top(r->bottom() + used_words); 315 r->reset_alloc_metadata_to_shared(); 316 317 _mutator_free_bitmap.clear_bit(r->region_number()); 318 } 319 320 // While individual regions report their true use, all humongous regions are 321 // marked used in the free set. 322 increase_used(ShenandoahHeapRegion::region_size_bytes() * num); 323 324 if (remainder != 0) { 325 // Record this remainder as allocation waste 326 _heap->notify_mutator_alloc_words(ShenandoahHeapRegion::region_size_words() - remainder, true); 327 } 328 329 // Allocated at left/rightmost? Move the bounds appropriately. 330 if (beg == _mutator_leftmost || end == _mutator_rightmost) { 331 adjust_bounds(); 332 } 333 assert_bounds(); 334 335 req.set_actual_size(words_size); 336 return _heap->get_region(beg)->bottom(); 337 } 338 339 bool ShenandoahFreeSet::is_empty_or_trash(ShenandoahHeapRegion *r) { 340 return r->is_empty() || r->is_trash(); 341 } 342 343 size_t ShenandoahFreeSet::alloc_capacity(ShenandoahHeapRegion *r) { 344 if (r->is_trash()) { 345 // This would be recycled on allocation path 346 return ShenandoahHeapRegion::region_size_bytes(); 347 } else { 348 return r->free(); 349 } 350 } 351 352 bool ShenandoahFreeSet::has_no_alloc_capacity(ShenandoahHeapRegion *r) { 353 return alloc_capacity(r) == 0; 354 } 355 356 void ShenandoahFreeSet::try_recycle_trashed(ShenandoahHeapRegion *r) { 357 if (r->is_trash()) { 358 _heap->decrease_used(r->used()); 359 r->recycle(); 360 } 361 } 362 363 void ShenandoahFreeSet::recycle_trash() { 364 // lock is not reentrable, check we don't have it 365 assert_heaplock_not_owned_by_current_thread(); 366 367 for (size_t i = 0; i < _heap->num_regions(); i++) { 368 ShenandoahHeapRegion* r = _heap->get_region(i); 369 if (r->is_trash()) { 370 ShenandoahHeapLocker locker(_heap->lock()); 371 try_recycle_trashed(r); 372 } 373 SpinPause(); // allow allocators to take the lock 374 } 375 } 376 377 void ShenandoahFreeSet::flip_to_gc(ShenandoahHeapRegion* r) { 378 size_t idx = r->region_number(); 379 380 assert(_mutator_free_bitmap.at(idx), "Should be in mutator view"); 381 assert(is_empty_or_trash(r), "Should not be allocated"); 382 383 _mutator_free_bitmap.clear_bit(idx); 384 _collector_free_bitmap.set_bit(idx); 385 _collector_leftmost = MIN2(idx, _collector_leftmost); 386 _collector_rightmost = MAX2(idx, _collector_rightmost); 387 388 _capacity -= alloc_capacity(r); 389 390 if (touches_bounds(idx)) { 391 adjust_bounds(); 392 } 393 assert_bounds(); 394 } 395 396 void ShenandoahFreeSet::clear() { 397 assert_heaplock_owned_by_current_thread(); 398 clear_internal(); 399 } 400 401 void ShenandoahFreeSet::clear_internal() { 402 _mutator_free_bitmap.clear(); 403 _collector_free_bitmap.clear(); 404 _mutator_leftmost = _max; 405 _mutator_rightmost = 0; 406 _collector_leftmost = _max; 407 _collector_rightmost = 0; 408 _capacity = 0; 409 _used = 0; 410 } 411 412 void ShenandoahFreeSet::rebuild() { 413 assert_heaplock_owned_by_current_thread(); 414 clear(); 415 416 for (size_t idx = 0; idx < _heap->num_regions(); idx++) { 417 ShenandoahHeapRegion* region = _heap->get_region(idx); 418 if (region->is_alloc_allowed() || region->is_trash()) { 419 assert(!region->is_cset(), "Shouldn't be adding those to the free set"); 420 421 // Do not add regions that would surely fail allocation 422 if (has_no_alloc_capacity(region)) continue; 423 424 _capacity += alloc_capacity(region); 425 assert(_used <= _capacity, "must not use more than we have"); 426 427 assert(!is_mutator_free(idx), "We are about to add it, it shouldn't be there already"); 428 _mutator_free_bitmap.set_bit(idx); 429 } 430 } 431 432 // Evac reserve: reserve trailing space for evacuations 433 size_t to_reserve = ShenandoahEvacReserve * _heap->capacity() / 100; 434 size_t reserved = 0; 435 436 for (size_t idx = _heap->num_regions() - 1; idx > 0; idx--) { 437 if (reserved >= to_reserve) break; 438 439 ShenandoahHeapRegion* region = _heap->get_region(idx); 440 if (_mutator_free_bitmap.at(idx) && is_empty_or_trash(region)) { 441 _mutator_free_bitmap.clear_bit(idx); 442 _collector_free_bitmap.set_bit(idx); 443 size_t ac = alloc_capacity(region); 444 _capacity -= ac; 445 reserved += ac; 446 } 447 } 448 449 recompute_bounds(); 450 assert_bounds(); 451 } 452 453 void ShenandoahFreeSet::log_status() { 454 assert_heaplock_owned_by_current_thread(); 455 456 LogTarget(Info, gc, ergo) lt; 457 if (lt.is_enabled()) { 458 ResourceMark rm; 459 LogStream ls(lt); 460 461 { 462 size_t last_idx = 0; 463 size_t max = 0; 464 size_t max_contig = 0; 465 size_t empty_contig = 0; 466 467 size_t total_used = 0; 468 size_t total_free = 0; 469 470 for (size_t idx = _mutator_leftmost; idx <= _mutator_rightmost; idx++) { 471 if (is_mutator_free(idx)) { 472 ShenandoahHeapRegion *r = _heap->get_region(idx); 473 size_t free = alloc_capacity(r); 474 475 max = MAX2(max, free); 476 477 if (r->is_empty() && (last_idx + 1 == idx)) { 478 empty_contig++; 479 } else { 480 empty_contig = 0; 481 } 482 483 total_used += r->used(); 484 total_free += free; 485 486 max_contig = MAX2(max_contig, empty_contig); 487 last_idx = idx; 488 } 489 } 490 491 size_t max_humongous = max_contig * ShenandoahHeapRegion::region_size_bytes(); 492 size_t free = capacity() - used(); 493 494 ls.print("Free: " SIZE_FORMAT "M (" SIZE_FORMAT " regions), Max regular: " SIZE_FORMAT "K, Max humongous: " SIZE_FORMAT "K, ", 495 total_free / M, mutator_count(), max / K, max_humongous / K); 496 497 size_t frag_ext; 498 if (free > 0) { 499 frag_ext = 100 - (100 * max_humongous / free); 500 } else { 501 frag_ext = 0; 502 } 503 ls.print("External frag: " SIZE_FORMAT "%%, ", frag_ext); 504 505 size_t frag_int; 506 if (mutator_count() > 0) { 507 frag_int = (100 * (total_used / mutator_count()) / ShenandoahHeapRegion::region_size_bytes()); 508 } else { 509 frag_int = 0; 510 } 511 ls.print("Internal frag: " SIZE_FORMAT "%%", frag_int); 512 ls.cr(); 513 } 514 515 { 516 size_t max = 0; 517 size_t total_free = 0; 518 519 for (size_t idx = _collector_leftmost; idx <= _collector_rightmost; idx++) { 520 if (is_collector_free(idx)) { 521 ShenandoahHeapRegion *r = _heap->get_region(idx); 522 size_t free = alloc_capacity(r); 523 max = MAX2(max, free); 524 total_free += free; 525 } 526 } 527 528 ls.print_cr("Evacuation Reserve: " SIZE_FORMAT "M (" SIZE_FORMAT " regions), Max regular: " SIZE_FORMAT "K", 529 total_free / M, collector_count(), max / K); 530 } 531 } 532 } 533 534 HeapWord* ShenandoahFreeSet::allocate(ShenandoahAllocRequest& req, bool& in_new_region) { 535 assert_heaplock_owned_by_current_thread(); 536 assert_bounds(); 537 538 if (req.size() > ShenandoahHeapRegion::humongous_threshold_words()) { 539 switch (req.type()) { 540 case ShenandoahAllocRequest::_alloc_shared: 541 case ShenandoahAllocRequest::_alloc_shared_gc: 542 in_new_region = true; 543 return allocate_contiguous(req); 544 case ShenandoahAllocRequest::_alloc_gclab: 545 case ShenandoahAllocRequest::_alloc_tlab: 546 in_new_region = false; 547 assert(false, "Trying to allocate TLAB larger than the humongous threshold: " SIZE_FORMAT " > " SIZE_FORMAT, 548 req.size(), ShenandoahHeapRegion::humongous_threshold_words()); 549 return NULL; 550 default: 551 ShouldNotReachHere(); 552 return NULL; 553 } 554 } else { 555 return allocate_single(req, in_new_region); 556 } 557 } 558 559 size_t ShenandoahFreeSet::unsafe_peek_free() const { 560 // Deliberately not locked, this method is unsafe when free set is modified. 561 562 for (size_t index = _mutator_leftmost; index <= _mutator_rightmost; index++) { 563 if (index < _max && is_mutator_free(index)) { 564 ShenandoahHeapRegion* r = _heap->get_region(index); 565 if (r->free() >= MinTLABSize) { 566 return r->free(); 567 } 568 } 569 } 570 571 // It appears that no regions left 572 return 0; 573 } 574 575 void ShenandoahFreeSet::print_on(outputStream* out) const { 576 out->print_cr("Mutator Free Set: " SIZE_FORMAT "", mutator_count()); 577 for (size_t index = _mutator_leftmost; index <= _mutator_rightmost; index++) { 578 if (is_mutator_free(index)) { 579 _heap->get_region(index)->print_on(out); 580 } 581 } 582 out->print_cr("Collector Free Set: " SIZE_FORMAT "", collector_count()); 583 for (size_t index = _collector_leftmost; index <= _collector_rightmost; index++) { 584 if (is_collector_free(index)) { 585 _heap->get_region(index)->print_on(out); 586 } 587 } 588 } 589 590 #ifdef ASSERT 591 void ShenandoahFreeSet::assert_heaplock_owned_by_current_thread() const { 592 _heap->assert_heaplock_owned_by_current_thread(); 593 } 594 595 void ShenandoahFreeSet::assert_heaplock_not_owned_by_current_thread() const { 596 _heap->assert_heaplock_not_owned_by_current_thread(); 597 } 598 599 void ShenandoahFreeSet::assert_bounds() const { 600 // Performance invariants. Failing these would not break the free set, but performance 601 // would suffer. 602 assert (_mutator_leftmost <= _max, "leftmost in bounds: " SIZE_FORMAT " < " SIZE_FORMAT, _mutator_leftmost, _max); 603 assert (_mutator_rightmost < _max, "rightmost in bounds: " SIZE_FORMAT " < " SIZE_FORMAT, _mutator_rightmost, _max); 604 605 assert (_mutator_leftmost == _max || is_mutator_free(_mutator_leftmost), "leftmost region should be free: " SIZE_FORMAT, _mutator_leftmost); 606 assert (_mutator_rightmost == 0 || is_mutator_free(_mutator_rightmost), "rightmost region should be free: " SIZE_FORMAT, _mutator_rightmost); 607 608 size_t beg_off = _mutator_free_bitmap.get_next_one_offset(0); 609 size_t end_off = _mutator_free_bitmap.get_next_one_offset(_mutator_rightmost + 1); 610 assert (beg_off >= _mutator_leftmost, "free regions before the leftmost: " SIZE_FORMAT ", bound " SIZE_FORMAT, beg_off, _mutator_leftmost); 611 assert (end_off == _max, "free regions past the rightmost: " SIZE_FORMAT ", bound " SIZE_FORMAT, end_off, _mutator_rightmost); 612 613 assert (_collector_leftmost <= _max, "leftmost in bounds: " SIZE_FORMAT " < " SIZE_FORMAT, _collector_leftmost, _max); 614 assert (_collector_rightmost < _max, "rightmost in bounds: " SIZE_FORMAT " < " SIZE_FORMAT, _collector_rightmost, _max); 615 616 assert (_collector_leftmost == _max || is_collector_free(_collector_leftmost), "leftmost region should be free: " SIZE_FORMAT, _collector_leftmost); 617 assert (_collector_rightmost == 0 || is_collector_free(_collector_rightmost), "rightmost region should be free: " SIZE_FORMAT, _collector_rightmost); 618 619 beg_off = _collector_free_bitmap.get_next_one_offset(0); 620 end_off = _collector_free_bitmap.get_next_one_offset(_collector_rightmost + 1); 621 assert (beg_off >= _collector_leftmost, "free regions before the leftmost: " SIZE_FORMAT ", bound " SIZE_FORMAT, beg_off, _collector_leftmost); 622 assert (end_off == _max, "free regions past the rightmost: " SIZE_FORMAT ", bound " SIZE_FORMAT, end_off, _collector_rightmost); 623 } 624 #endif