1 /*
   2  * Copyright (c) 2003, 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 #include "precompiled.hpp"
  26 #include "gc/parallel/asPSYoungGen.hpp"
  27 #include "gc/parallel/parallelScavengeHeap.hpp"
  28 #include "gc/parallel/psMarkSweepDecorator.hpp"
  29 #include "gc/parallel/psScavenge.hpp"
  30 #include "gc/parallel/psYoungGen.hpp"
  31 #include "gc/shared/gcUtil.hpp"
  32 #include "gc/shared/spaceDecorator.hpp"
  33 #include "oops/oop.inline.hpp"
  34 #include "runtime/java.hpp"
  35 
  36 ASPSYoungGen::ASPSYoungGen(size_t init_byte_size,
  37                            size_t minimum_byte_size,
  38                            size_t byte_size_limit) :
  39   PSYoungGen(init_byte_size, minimum_byte_size, byte_size_limit),
  40   _gen_size_limit(byte_size_limit) {
  41 }
  42 
  43 
  44 ASPSYoungGen::ASPSYoungGen(PSVirtualSpace* vs,
  45                            size_t init_byte_size,
  46                            size_t minimum_byte_size,
  47                            size_t byte_size_limit) :
  48   //PSYoungGen(init_byte_size, minimum_byte_size, byte_size_limit),
  49   PSYoungGen(vs->committed_size(), minimum_byte_size, byte_size_limit),
  50   _gen_size_limit(byte_size_limit) {
  51 
  52   assert(vs->committed_size() == init_byte_size, "Cannot replace with");
  53 
  54   _virtual_space = vs;
  55 }
  56 
  57 void ASPSYoungGen::initialize_virtual_space(ReservedSpace rs,
  58                                             size_t alignment) {
  59   assert(_init_gen_size != 0, "Should have a finite size");
  60   _virtual_space = new PSVirtualSpaceHighToLow(rs, alignment);
  61   if (!_virtual_space->expand_by(_init_gen_size)) {
  62     vm_exit_during_initialization("Could not reserve enough space for "
  63                                   "object heap");
  64   }
  65 }
  66 
  67 void ASPSYoungGen::initialize(ReservedSpace rs, size_t alignment) {
  68   initialize_virtual_space(rs, alignment);
  69   initialize_work();
  70 }
  71 
  72 size_t ASPSYoungGen::available_for_expansion() {
  73   size_t current_committed_size = virtual_space()->committed_size();
  74   assert((gen_size_limit() >= current_committed_size),
  75     "generation size limit is wrong");
  76   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
  77   size_t result =  gen_size_limit() - current_committed_size;
  78   size_t result_aligned = align_size_down(result, heap->generation_alignment());
  79   return result_aligned;
  80 }
  81 
  82 // Return the number of bytes the young gen is willing give up.
  83 //
  84 // Future implementations could check the survivors and if to_space is in the
  85 // right place (below from_space), take a chunk from to_space.
  86 size_t ASPSYoungGen::available_for_contraction() {
  87   size_t uncommitted_bytes = virtual_space()->uncommitted_size();
  88   if (uncommitted_bytes != 0) {
  89     return uncommitted_bytes;
  90   }
  91 
  92   if (eden_space()->is_empty()) {
  93     // Respect the minimum size for eden and for the young gen as a whole.
  94     ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
  95     const size_t eden_alignment = heap->space_alignment();
  96     const size_t gen_alignment = heap->generation_alignment();
  97 
  98     assert(eden_space()->capacity_in_bytes() >= eden_alignment,
  99       "Alignment is wrong");
 100     size_t eden_avail = eden_space()->capacity_in_bytes() - eden_alignment;
 101     eden_avail = align_size_down(eden_avail, gen_alignment);
 102 
 103     assert(virtual_space()->committed_size() >= min_gen_size(),
 104       "minimum gen size is wrong");
 105     size_t gen_avail = virtual_space()->committed_size() - min_gen_size();
 106     assert(virtual_space()->is_aligned(gen_avail), "not aligned");
 107 
 108     const size_t max_contraction = MIN2(eden_avail, gen_avail);
 109     // See comment for ASPSOldGen::available_for_contraction()
 110     // for reasons the "increment" fraction is used.
 111     PSAdaptiveSizePolicy* policy = heap->size_policy();
 112     size_t result = policy->eden_increment_aligned_down(max_contraction);
 113     size_t result_aligned = align_size_down(result, gen_alignment);
 114     if (PrintAdaptiveSizePolicy && Verbose) {
 115       gclog_or_tty->print_cr("ASPSYoungGen::available_for_contraction: " SIZE_FORMAT " K",
 116         result_aligned/K);
 117       gclog_or_tty->print_cr("  max_contraction " SIZE_FORMAT " K", max_contraction/K);
 118       gclog_or_tty->print_cr("  eden_avail " SIZE_FORMAT " K", eden_avail/K);
 119       gclog_or_tty->print_cr("  gen_avail " SIZE_FORMAT " K", gen_avail/K);
 120     }
 121     return result_aligned;
 122   }
 123 
 124   return 0;
 125 }
 126 
 127 // The current implementation only considers to the end of eden.
 128 // If to_space is below from_space, to_space is not considered.
 129 // to_space can be.
 130 size_t ASPSYoungGen::available_to_live() {
 131   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
 132   const size_t alignment = heap->space_alignment();
 133 
 134   // Include any space that is committed but is not in eden.
 135   size_t available = pointer_delta(eden_space()->bottom(),
 136                                    virtual_space()->low(),
 137                                    sizeof(char));
 138 
 139   const size_t eden_capacity = eden_space()->capacity_in_bytes();
 140   if (eden_space()->is_empty() && eden_capacity > alignment) {
 141     available += eden_capacity - alignment;
 142   }
 143   return available;
 144 }
 145 
 146 // Similar to PSYoungGen::resize_generation() but
 147 //  allows sum of eden_size and 2 * survivor_size to exceed _max_gen_size
 148 //  expands at the low end of the virtual space
 149 //  moves the boundary between the generations in order to expand
 150 //  some additional diagnostics
 151 // If no additional changes are required, this can be deleted
 152 // and the changes factored back into PSYoungGen::resize_generation().
 153 bool ASPSYoungGen::resize_generation(size_t eden_size, size_t survivor_size) {
 154   const size_t alignment = virtual_space()->alignment();
 155   size_t orig_size = virtual_space()->committed_size();
 156   bool size_changed = false;
 157 
 158   // There used to be a guarantee here that
 159   //   (eden_size + 2*survivor_size)  <= _max_gen_size
 160   // This requirement is enforced by the calculation of desired_size
 161   // below.  It may not be true on entry since the size of the
 162   // eden_size is no bounded by the generation size.
 163 
 164   assert(max_size() == reserved().byte_size(), "max gen size problem?");
 165   assert(min_gen_size() <= orig_size && orig_size <= max_size(),
 166          "just checking");
 167 
 168   // Adjust new generation size
 169   const size_t eden_plus_survivors =
 170     align_size_up(eden_size + 2 * survivor_size, alignment);
 171   size_t desired_size = MAX2(MIN2(eden_plus_survivors, gen_size_limit()),
 172                              min_gen_size());
 173   assert(desired_size <= gen_size_limit(), "just checking");
 174 
 175   if (desired_size > orig_size) {
 176     // Grow the generation
 177     size_t change = desired_size - orig_size;
 178     HeapWord* prev_low = (HeapWord*) virtual_space()->low();
 179     if (!virtual_space()->expand_by(change)) {
 180       return false;
 181     }
 182     if (ZapUnusedHeapArea) {
 183       // Mangle newly committed space immediately because it
 184       // can be done here more simply that after the new
 185       // spaces have been computed.
 186       HeapWord* new_low = (HeapWord*) virtual_space()->low();
 187       assert(new_low < prev_low, "Did not grow");
 188 
 189       MemRegion mangle_region(new_low, prev_low);
 190       SpaceMangler::mangle_region(mangle_region);
 191     }
 192     size_changed = true;
 193   } else if (desired_size < orig_size) {
 194     size_t desired_change = orig_size - desired_size;
 195 
 196     // How much is available for shrinking.
 197     size_t available_bytes = limit_gen_shrink(desired_change);
 198     size_t change = MIN2(desired_change, available_bytes);
 199     virtual_space()->shrink_by(change);
 200     size_changed = true;
 201   } else {
 202     if (Verbose && PrintGC) {
 203       if (orig_size == gen_size_limit()) {
 204         gclog_or_tty->print_cr("ASPSYoung generation size at maximum: "
 205           SIZE_FORMAT "K", orig_size/K);
 206       } else if (orig_size == min_gen_size()) {
 207         gclog_or_tty->print_cr("ASPSYoung generation size at minium: "
 208           SIZE_FORMAT "K", orig_size/K);
 209       }
 210     }
 211   }
 212 
 213   if (size_changed) {
 214     reset_after_change();
 215     if (Verbose && PrintGC) {
 216       size_t current_size  = virtual_space()->committed_size();
 217       gclog_or_tty->print_cr("ASPSYoung generation size changed: "
 218         SIZE_FORMAT "K->" SIZE_FORMAT "K",
 219         orig_size/K, current_size/K);
 220     }
 221   }
 222 
 223   guarantee(eden_plus_survivors <= virtual_space()->committed_size() ||
 224             virtual_space()->committed_size() == max_size(), "Sanity");
 225 
 226   return true;
 227 }
 228 
 229 // Similar to PSYoungGen::resize_spaces() but
 230 //  eden always starts at the low end of the committed virtual space
 231 //  current implementation does not allow holes between the spaces
 232 //  _young_generation_boundary has to be reset because it changes.
 233 //  so additional verification
 234 
 235 void ASPSYoungGen::resize_spaces(size_t requested_eden_size,
 236                                  size_t requested_survivor_size) {
 237   assert(UseAdaptiveSizePolicy, "sanity check");
 238   assert(requested_eden_size > 0 && requested_survivor_size > 0,
 239          "just checking");
 240 
 241   space_invariants();
 242 
 243   // We require eden and to space to be empty
 244   if ((!eden_space()->is_empty()) || (!to_space()->is_empty())) {
 245     return;
 246   }
 247 
 248   if (PrintAdaptiveSizePolicy && Verbose) {
 249     gclog_or_tty->print_cr("PSYoungGen::resize_spaces(requested_eden_size: "
 250                   SIZE_FORMAT
 251                   ", requested_survivor_size: " SIZE_FORMAT ")",
 252                   requested_eden_size, requested_survivor_size);
 253     gclog_or_tty->print_cr("    eden: [" PTR_FORMAT ".." PTR_FORMAT ") "
 254                   SIZE_FORMAT,
 255                   p2i(eden_space()->bottom()),
 256                   p2i(eden_space()->end()),
 257                   pointer_delta(eden_space()->end(),
 258                                 eden_space()->bottom(),
 259                                 sizeof(char)));
 260     gclog_or_tty->print_cr("    from: [" PTR_FORMAT ".." PTR_FORMAT ") "
 261                   SIZE_FORMAT,
 262                   p2i(from_space()->bottom()),
 263                   p2i(from_space()->end()),
 264                   pointer_delta(from_space()->end(),
 265                                 from_space()->bottom(),
 266                                 sizeof(char)));
 267     gclog_or_tty->print_cr("      to: [" PTR_FORMAT ".." PTR_FORMAT ") "
 268                   SIZE_FORMAT,
 269                   p2i(to_space()->bottom()),
 270                   p2i(to_space()->end()),
 271                   pointer_delta(  to_space()->end(),
 272                                   to_space()->bottom(),
 273                                   sizeof(char)));
 274   }
 275 
 276   // There's nothing to do if the new sizes are the same as the current
 277   if (requested_survivor_size == to_space()->capacity_in_bytes() &&
 278       requested_survivor_size == from_space()->capacity_in_bytes() &&
 279       requested_eden_size == eden_space()->capacity_in_bytes()) {
 280     if (PrintAdaptiveSizePolicy && Verbose) {
 281       gclog_or_tty->print_cr("    capacities are the right sizes, returning");
 282     }
 283     return;
 284   }
 285 
 286   char* eden_start = (char*)virtual_space()->low();
 287   char* eden_end   = (char*)eden_space()->end();
 288   char* from_start = (char*)from_space()->bottom();
 289   char* from_end   = (char*)from_space()->end();
 290   char* to_start   = (char*)to_space()->bottom();
 291   char* to_end     = (char*)to_space()->end();
 292 
 293   assert(eden_start < from_start, "Cannot push into from_space");
 294 
 295   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
 296   const size_t alignment = heap->space_alignment();
 297   const bool maintain_minimum =
 298     (requested_eden_size + 2 * requested_survivor_size) <= min_gen_size();
 299 
 300   bool eden_from_to_order = from_start < to_start;
 301   // Check whether from space is below to space
 302   if (eden_from_to_order) {
 303     // Eden, from, to
 304 
 305     if (PrintAdaptiveSizePolicy && Verbose) {
 306       gclog_or_tty->print_cr("  Eden, from, to:");
 307     }
 308 
 309     // Set eden
 310     // "requested_eden_size" is a goal for the size of eden
 311     // and may not be attainable.  "eden_size" below is
 312     // calculated based on the location of from-space and
 313     // the goal for the size of eden.  from-space is
 314     // fixed in place because it contains live data.
 315     // The calculation is done this way to avoid 32bit
 316     // overflow (i.e., eden_start + requested_eden_size
 317     // may too large for representation in 32bits).
 318     size_t eden_size;
 319     if (maintain_minimum) {
 320       // Only make eden larger than the requested size if
 321       // the minimum size of the generation has to be maintained.
 322       // This could be done in general but policy at a higher
 323       // level is determining a requested size for eden and that
 324       // should be honored unless there is a fundamental reason.
 325       eden_size = pointer_delta(from_start,
 326                                 eden_start,
 327                                 sizeof(char));
 328     } else {
 329       eden_size = MIN2(requested_eden_size,
 330                        pointer_delta(from_start, eden_start, sizeof(char)));
 331     }
 332 
 333     eden_end = eden_start + eden_size;
 334     assert(eden_end >= eden_start, "addition overflowed");
 335 
 336     // To may resize into from space as long as it is clear of live data.
 337     // From space must remain page aligned, though, so we need to do some
 338     // extra calculations.
 339 
 340     // First calculate an optimal to-space
 341     to_end   = (char*)virtual_space()->high();
 342     to_start = (char*)pointer_delta(to_end,
 343                                     (char*)requested_survivor_size,
 344                                     sizeof(char));
 345 
 346     // Does the optimal to-space overlap from-space?
 347     if (to_start < (char*)from_space()->end()) {
 348       // Calculate the minimum offset possible for from_end
 349       size_t from_size =
 350         pointer_delta(from_space()->top(), from_start, sizeof(char));
 351 
 352       // Should we be in this method if from_space is empty? Why not the set_space method? FIX ME!
 353       if (from_size == 0) {
 354         from_size = alignment;
 355       } else {
 356         from_size = align_size_up(from_size, alignment);
 357       }
 358 
 359       from_end = from_start + from_size;
 360       assert(from_end > from_start, "addition overflow or from_size problem");
 361 
 362       guarantee(from_end <= (char*)from_space()->end(),
 363         "from_end moved to the right");
 364 
 365       // Now update to_start with the new from_end
 366       to_start = MAX2(from_end, to_start);
 367     }
 368 
 369     guarantee(to_start != to_end, "to space is zero sized");
 370 
 371     if (PrintAdaptiveSizePolicy && Verbose) {
 372       gclog_or_tty->print_cr("    [eden_start .. eden_end): "
 373                     "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
 374                     p2i(eden_start),
 375                     p2i(eden_end),
 376                     pointer_delta(eden_end, eden_start, sizeof(char)));
 377       gclog_or_tty->print_cr("    [from_start .. from_end): "
 378                     "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
 379                     p2i(from_start),
 380                     p2i(from_end),
 381                     pointer_delta(from_end, from_start, sizeof(char)));
 382       gclog_or_tty->print_cr("    [  to_start ..   to_end): "
 383                     "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
 384                     p2i(to_start),
 385                     p2i(to_end),
 386                     pointer_delta(  to_end,   to_start, sizeof(char)));
 387     }
 388   } else {
 389     // Eden, to, from
 390     if (PrintAdaptiveSizePolicy && Verbose) {
 391       gclog_or_tty->print_cr("  Eden, to, from:");
 392     }
 393 
 394     // To space gets priority over eden resizing. Note that we position
 395     // to space as if we were able to resize from space, even though from
 396     // space is not modified.
 397     // Giving eden priority was tried and gave poorer performance.
 398     to_end   = (char*)pointer_delta(virtual_space()->high(),
 399                                     (char*)requested_survivor_size,
 400                                     sizeof(char));
 401     to_end   = MIN2(to_end, from_start);
 402     to_start = (char*)pointer_delta(to_end, (char*)requested_survivor_size,
 403                                     sizeof(char));
 404     // if the space sizes are to be increased by several times then
 405     // 'to_start' will point beyond the young generation. In this case
 406     // 'to_start' should be adjusted.
 407     to_start = MAX2(to_start, eden_start + alignment);
 408 
 409     // Compute how big eden can be, then adjust end.
 410     // See  comments above on calculating eden_end.
 411     size_t eden_size;
 412     if (maintain_minimum) {
 413       eden_size = pointer_delta(to_start, eden_start, sizeof(char));
 414     } else {
 415       eden_size = MIN2(requested_eden_size,
 416                        pointer_delta(to_start, eden_start, sizeof(char)));
 417     }
 418     eden_end = eden_start + eden_size;
 419     assert(eden_end >= eden_start, "addition overflowed");
 420 
 421     // Don't let eden shrink down to 0 or less.
 422     eden_end = MAX2(eden_end, eden_start + alignment);
 423     to_start = MAX2(to_start, eden_end);
 424 
 425     if (PrintAdaptiveSizePolicy && Verbose) {
 426       gclog_or_tty->print_cr("    [eden_start .. eden_end): "
 427                     "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
 428                     p2i(eden_start),
 429                     p2i(eden_end),
 430                     pointer_delta(eden_end, eden_start, sizeof(char)));
 431       gclog_or_tty->print_cr("    [  to_start ..   to_end): "
 432                     "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
 433                     p2i(to_start),
 434                     p2i(to_end),
 435                     pointer_delta(  to_end,   to_start, sizeof(char)));
 436       gclog_or_tty->print_cr("    [from_start .. from_end): "
 437                     "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
 438                     p2i(from_start),
 439                     p2i(from_end),
 440                     pointer_delta(from_end, from_start, sizeof(char)));
 441     }
 442   }
 443 
 444 
 445   guarantee((HeapWord*)from_start <= from_space()->bottom(),
 446             "from start moved to the right");
 447   guarantee((HeapWord*)from_end >= from_space()->top(),
 448             "from end moved into live data");
 449   assert(is_object_aligned((intptr_t)eden_start), "checking alignment");
 450   assert(is_object_aligned((intptr_t)from_start), "checking alignment");
 451   assert(is_object_aligned((intptr_t)to_start), "checking alignment");
 452 
 453   MemRegion edenMR((HeapWord*)eden_start, (HeapWord*)eden_end);
 454   MemRegion toMR  ((HeapWord*)to_start,   (HeapWord*)to_end);
 455   MemRegion fromMR((HeapWord*)from_start, (HeapWord*)from_end);
 456 
 457   // Let's make sure the call to initialize doesn't reset "top"!
 458   DEBUG_ONLY(HeapWord* old_from_top = from_space()->top();)
 459 
 460   // For PrintAdaptiveSizePolicy block  below
 461   size_t old_from = from_space()->capacity_in_bytes();
 462   size_t old_to   = to_space()->capacity_in_bytes();
 463 
 464   if (ZapUnusedHeapArea) {
 465     // NUMA is a special case because a numa space is not mangled
 466     // in order to not prematurely bind its address to memory to
 467     // the wrong memory (i.e., don't want the GC thread to first
 468     // touch the memory).  The survivor spaces are not numa
 469     // spaces and are mangled.
 470     if (UseNUMA) {
 471       if (eden_from_to_order) {
 472         mangle_survivors(from_space(), fromMR, to_space(), toMR);
 473       } else {
 474         mangle_survivors(to_space(), toMR, from_space(), fromMR);
 475       }
 476     }
 477 
 478     // If not mangling the spaces, do some checking to verify that
 479     // the spaces are already mangled.
 480     // The spaces should be correctly mangled at this point so
 481     // do some checking here. Note that they are not being mangled
 482     // in the calls to initialize().
 483     // Must check mangling before the spaces are reshaped.  Otherwise,
 484     // the bottom or end of one space may have moved into an area
 485     // covered by another space and a failure of the check may
 486     // not correctly indicate which space is not properly mangled.
 487 
 488     HeapWord* limit = (HeapWord*) virtual_space()->high();
 489     eden_space()->check_mangled_unused_area(limit);
 490     from_space()->check_mangled_unused_area(limit);
 491       to_space()->check_mangled_unused_area(limit);
 492   }
 493   // When an existing space is being initialized, it is not
 494   // mangled because the space has been previously mangled.
 495   eden_space()->initialize(edenMR,
 496                            SpaceDecorator::Clear,
 497                            SpaceDecorator::DontMangle);
 498     to_space()->initialize(toMR,
 499                            SpaceDecorator::Clear,
 500                            SpaceDecorator::DontMangle);
 501   from_space()->initialize(fromMR,
 502                            SpaceDecorator::DontClear,
 503                            SpaceDecorator::DontMangle);
 504 
 505   PSScavenge::set_young_generation_boundary(eden_space()->bottom());
 506 
 507   assert(from_space()->top() == old_from_top, "from top changed!");
 508 
 509   if (PrintAdaptiveSizePolicy) {
 510     ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
 511     gclog_or_tty->print("AdaptiveSizePolicy::survivor space sizes: "
 512                   "collection: %d "
 513                   "(" SIZE_FORMAT ", " SIZE_FORMAT ") -> "
 514                   "(" SIZE_FORMAT ", " SIZE_FORMAT ") ",
 515                   heap->total_collections(),
 516                   old_from, old_to,
 517                   from_space()->capacity_in_bytes(),
 518                   to_space()->capacity_in_bytes());
 519     gclog_or_tty->cr();
 520   }
 521   space_invariants();
 522 }
 523 void ASPSYoungGen::reset_after_change() {
 524   assert_locked_or_safepoint(Heap_lock);
 525 
 526   _reserved = MemRegion((HeapWord*)virtual_space()->low_boundary(),
 527                         (HeapWord*)virtual_space()->high_boundary());
 528   PSScavenge::reference_processor()->set_span(_reserved);
 529 
 530   HeapWord* new_eden_bottom = (HeapWord*)virtual_space()->low();
 531   HeapWord* eden_bottom = eden_space()->bottom();
 532   if (new_eden_bottom != eden_bottom) {
 533     MemRegion eden_mr(new_eden_bottom, eden_space()->end());
 534     eden_space()->initialize(eden_mr,
 535                              SpaceDecorator::Clear,
 536                              SpaceDecorator::Mangle);
 537     PSScavenge::set_young_generation_boundary(eden_space()->bottom());
 538   }
 539   MemRegion cmr((HeapWord*)virtual_space()->low(),
 540                 (HeapWord*)virtual_space()->high());
 541   ParallelScavengeHeap::heap()->barrier_set()->resize_covered_region(cmr);
 542 
 543   space_invariants();
 544 }
--- EOF ---