bool DefNewGeneration::expand(size_t bytes) {
MutexLocker x(ExpandHeap_lock);
HeapWord* prev_high = (HeapWord*) _virtual_space.high();
bool success = _virtual_space.expand_by(bytes);
if (success && ZapUnusedHeapArea) {
// Mangle newly committed space immediately because it
// can be done here more simply that after the new
// spaces have been computed.
HeapWord* new_high = (HeapWord*) _virtual_space.high();
MemRegion mangle_region(prev_high, new_high);
SpaceMangler::mangle_region(mangle_region);
}
// Do not attempt an expand-to-the reserve size. The
// request should properly observe the maximum size of
// the generation so an expand-to-reserve should be
// unnecessary. Also a second call to expand-to-reserve
// value potentially can cause an undue expansion.
// For example if the first expand fail for unknown reasons,
// but the second succeeds and expands the heap to its maximum
// value.
if (GC_locker::is_active()) {
if (PrintGC && Verbose) {
gclog_or_tty->print_cr("Garbage collection disabled, "
"expanded heap instead");
}
}
return success;
}
bool CardGeneration::grow_by(size_t bytes) {
assert_correct_size_change_locking();
bool result = _virtual_space.expand_by(bytes);
if (result) {
size_t new_word_size =
heap_word_size(_virtual_space.committed_size());
MemRegion mr(space()->bottom(), new_word_size);
// Expand card table
GenCollectedHeap::heap()->barrier_set()->resize_covered_region(mr);
// Expand shared block offset array
_bts->resize(new_word_size);
// Fix for bug #4668531
if (ZapUnusedHeapArea) {
MemRegion mangle_region(space()->end(),
(HeapWord*)_virtual_space.high());
SpaceMangler::mangle_region(mangle_region);
}
// Expand space -- also expands space's BOT
// (which uses (part of) shared array above)
space()->set_end((HeapWord*)_virtual_space.high());
// update the space and generation capacity counters
update_counters();
size_t new_mem_size = _virtual_space.committed_size();
size_t old_mem_size = new_mem_size - bytes;
log_trace(gc, heap)("Expanding %s from " SIZE_FORMAT "K by " SIZE_FORMAT "K to " SIZE_FORMAT "K",
name(), old_mem_size/K, bytes/K, new_mem_size/K);
}
return result;
}
Generation::Generation(ReservedSpace rs, size_t initial_size, int level) :
_level(level),
_ref_processor(NULL) {
if (!_virtual_space.initialize(rs, initial_size)) {
vm_exit_during_initialization("Could not reserve enough space for "
"object heap");
}
// Mangle all of the the initial generation.
if (ZapUnusedHeapArea) {
MemRegion mangle_region((HeapWord*)_virtual_space.low(),
(HeapWord*)_virtual_space.high());
SpaceMangler::mangle_region(mangle_region);
}
_reserved = MemRegion((HeapWord*)_virtual_space.low_boundary(),
(HeapWord*)_virtual_space.high_boundary());
}
bool OneContigSpaceCardGeneration::grow_by(size_t bytes) {
assert_locked_or_safepoint(ExpandHeap_lock);
bool result = _virtual_space.expand_by(bytes);
if (result) {
size_t new_word_size =
heap_word_size(_virtual_space.committed_size());
MemRegion mr(_the_space->bottom(), new_word_size);
// Expand card table
Universe::heap()->barrier_set()->resize_covered_region(mr);
// Expand shared block offset array
_bts->resize(new_word_size);
// Fix for bug #4668531
if (ZapUnusedHeapArea) {
MemRegion mangle_region(_the_space->end(),
(HeapWord*)_virtual_space.high());
SpaceMangler::mangle_region(mangle_region);
}
// Expand space -- also expands space's BOT
// (which uses (part of) shared array above)
_the_space->set_end((HeapWord*)_virtual_space.high());
// update the space and generation capacity counters
update_counters();
if (Verbose && PrintGC) {
size_t new_mem_size = _virtual_space.committed_size();
size_t old_mem_size = new_mem_size - bytes;
gclog_or_tty->print_cr("Expanding %s from " SIZE_FORMAT "K by "
SIZE_FORMAT "K to " SIZE_FORMAT "K",
name(), old_mem_size/K, bytes/K, new_mem_size/K);
}
}
return result;
}
// NOTE! We need to be careful about resizing. During a GC, multiple
// allocators may be active during heap expansion. If we allow the
// heap resizing to become visible before we have correctly resized
// all heap related data structures, we may cause program failures.
void PSOldGen::post_resize() {
// First construct a memregion representing the new size
MemRegion new_memregion((HeapWord*)_virtual_space.low(), (HeapWord*)_virtual_space.high());
size_t new_word_size = new_memregion.word_size();
// Block offset table resize FIX ME!!!!!
// _bts->resize(new_word_size);
Universe::heap()->barrier_set()->resize_covered_region(new_memregion);
// Did we expand?
if (object_space()->end() < (HeapWord*) _virtual_space.high()) {
// We need to mangle the newly expanded area. The memregion spans
// end -> new_end, we assume that top -> end is already mangled.
// This cannot be safely tested for, as allocation may be taking
// place.
MemRegion mangle_region(object_space()->end(),(HeapWord*) _virtual_space.high());
object_space()->mangle_region(mangle_region);
}
// ALWAYS do this last!!
object_space()->set_end((HeapWord*) _virtual_space.high());
assert(new_word_size == heap_word_size(object_space()->capacity_in_bytes()), "Sanity");
}
bool PSYoungGen::resize_generation(size_t eden_size, size_t survivor_size) {
const size_t alignment = virtual_space()->alignment();
size_t orig_size = virtual_space()->committed_size();
bool size_changed = false;
// There used to be this guarantee there.
// guarantee ((eden_size + 2*survivor_size) <= _max_gen_size, "incorrect input arguments");
// Code below forces this requirement. In addition the desired eden
// size and disired survivor sizes are desired goals and may
// exceed the total generation size.
assert(min_gen_size() <= orig_size && orig_size <= max_size(), "just checking");
// Adjust new generation size
const size_t eden_plus_survivors =
align_size_up(eden_size + 2 * survivor_size, alignment);
size_t desired_size = MAX2(MIN2(eden_plus_survivors, max_size()),
min_gen_size());
assert(desired_size <= max_size(), "just checking");
if (desired_size > orig_size) {
// Grow the generation
size_t change = desired_size - orig_size;
assert(change % alignment == 0, "just checking");
HeapWord* prev_high = (HeapWord*) virtual_space()->high();
if (!virtual_space()->expand_by(change)) {
return false; // Error if we fail to resize!
}
if (ZapUnusedHeapArea) {
// Mangle newly committed space immediately because it
// can be done here more simply that after the new
// spaces have been computed.
HeapWord* new_high = (HeapWord*) virtual_space()->high();
MemRegion mangle_region(prev_high, new_high);
SpaceMangler::mangle_region(mangle_region);
}
size_changed = true;
} else if (desired_size < orig_size) {
size_t desired_change = orig_size - desired_size;
assert(desired_change % alignment == 0, "just checking");
desired_change = limit_gen_shrink(desired_change);
if (desired_change > 0) {
virtual_space()->shrink_by(desired_change);
reset_survivors_after_shrink();
size_changed = true;
}
} else {
if (Verbose && PrintGC) {
if (orig_size == gen_size_limit()) {
gclog_or_tty->print_cr("PSYoung generation size at maximum: "
SIZE_FORMAT "K", orig_size/K);
} else if (orig_size == min_gen_size()) {
gclog_or_tty->print_cr("PSYoung generation size at minium: "
SIZE_FORMAT "K", orig_size/K);
}
}
}
if (size_changed) {
post_resize();
if (Verbose && PrintGC) {
size_t current_size = virtual_space()->committed_size();
gclog_or_tty->print_cr("PSYoung generation size changed: "
SIZE_FORMAT "K->" SIZE_FORMAT "K",
orig_size/K, current_size/K);
}
}
guarantee(eden_plus_survivors <= virtual_space()->committed_size() ||
virtual_space()->committed_size() == max_size(), "Sanity");
return true;
}
// Similar to PSYoungGen::resize_generation() but
// allows sum of eden_size and 2 * survivor_size to exceed _max_gen_size
// expands at the low end of the virtual space
// moves the boundary between the generations in order to expand
// some additional diagnostics
// If no additional changes are required, this can be deleted
// and the changes factored back into PSYoungGen::resize_generation().
bool ASPSYoungGen::resize_generation(size_t eden_size, size_t survivor_size) {
const size_t alignment = virtual_space()->alignment();
size_t orig_size = virtual_space()->committed_size();
bool size_changed = false;
// There used to be a guarantee here that
// (eden_size + 2*survivor_size) <= _max_gen_size
// This requirement is enforced by the calculation of desired_size
// below. It may not be true on entry since the size of the
// eden_size is no bounded by the generation size.
assert(max_size() == reserved().byte_size(), "max gen size problem?");
assert(min_gen_size() <= orig_size && orig_size <= max_size(),
"just checking");
// Adjust new generation size
const size_t eden_plus_survivors =
align_size_up(eden_size + 2 * survivor_size, alignment);
size_t desired_size = MAX2(MIN2(eden_plus_survivors, gen_size_limit()),
min_gen_size());
assert(desired_size <= gen_size_limit(), "just checking");
if (desired_size > orig_size) {
// Grow the generation
size_t change = desired_size - orig_size;
HeapWord* prev_low = (HeapWord*) virtual_space()->low();
if (!virtual_space()->expand_by(change)) {
return false;
}
if (ZapUnusedHeapArea) {
// Mangle newly committed space immediately because it
// can be done here more simply that after the new
// spaces have been computed.
HeapWord* new_low = (HeapWord*) virtual_space()->low();
assert(new_low < prev_low, "Did not grow");
MemRegion mangle_region(new_low, prev_low);
SpaceMangler::mangle_region(mangle_region);
}
size_changed = true;
} else if (desired_size < orig_size) {
size_t desired_change = orig_size - desired_size;
// How much is available for shrinking.
size_t available_bytes = limit_gen_shrink(desired_change);
size_t change = MIN2(desired_change, available_bytes);
virtual_space()->shrink_by(change);
size_changed = true;
} else {
if (Verbose && PrintGC) {
if (orig_size == gen_size_limit()) {
gclog_or_tty->print_cr("ASPSYoung generation size at maximum: "
SIZE_FORMAT "K", orig_size/K);
} else if (orig_size == min_gen_size()) {
gclog_or_tty->print_cr("ASPSYoung generation size at minium: "
SIZE_FORMAT "K", orig_size/K);
}
}
}
if (size_changed) {
reset_after_change();
if (Verbose && PrintGC) {
size_t current_size = virtual_space()->committed_size();
gclog_or_tty->print_cr("ASPSYoung generation size changed: "
SIZE_FORMAT "K->" SIZE_FORMAT "K",
orig_size/K, current_size/K);
}
}
guarantee(eden_plus_survivors <= virtual_space()->committed_size() ||
virtual_space()->committed_size() == max_size(), "Sanity");
return true;
}
void ContiguousSpace::mangle_unused_area() {
// to-space is used for storing marks during mark-sweep
mangle_region(MemRegion(top(), end()));
}