void do_object(oop obj) {
if (obj->is_shared()) {
return;
}
if (obj->is_gc_marked() && obj->forwardee() == NULL) {
int s = obj->size();
oop sh_obj = (oop)_space->allocate(s);
if (sh_obj == NULL) {
if (_read_only) {
warning("\nThe permanent generation read only space is not large "
"enough to \npreload requested classes. Use "
"-XX:SharedReadOnlySize= to increase \nthe initial "
"size of the read only space.\n");
} else {
warning("\nThe permanent generation read write space is not large "
"enough to \npreload requested classes. Use "
"-XX:SharedReadWriteSize= to increase \nthe initial "
"size of the read write space.\n");
}
exit(2);
}
if (PrintSharedSpaces && Verbose && WizardMode) {
tty->print_cr("\nMoveMarkedObjects: " PTR_FORMAT " -> " PTR_FORMAT " %s", obj, sh_obj,
(_read_only ? "ro" : "rw"));
}
Copy::aligned_disjoint_words((HeapWord*)obj, (HeapWord*)sh_obj, s);
obj->forward_to(sh_obj);
if (_read_only) {
// Readonly objects: set hash value to self pointer and make gc_marked.
sh_obj->forward_to(sh_obj);
} else {
sh_obj->init_mark();
}
}
}
void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
assert(from_obj->is_forwarded(), "from obj should be forwarded");
assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
assert(from_obj != to_obj, "should not be self-forwarded");
assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
// The object might be in the process of being copied by another
// worker so we cannot trust that its to-space image is
// well-formed. So we have to read its size from its from-space
// image which we know should not be changing.
_cm->grayRoot(to_obj);
}
inline oop PSPromotionManager::copy_to_survivor_space(oop o) {
assert(should_scavenge(&o), "Sanity");
oop new_obj = NULL;
// NOTE! We must be very careful with any methods that access the mark
// in o. There may be multiple threads racing on it, and it may be forwarded
// at any time. Do not use oop methods for accessing the mark!
markOop test_mark = o->mark();
// The same test as "o->is_forwarded()"
if (!test_mark->is_marked()) {
bool new_obj_is_tenured = false;
size_t new_obj_size = o->size();
// Find the objects age, MT safe.
uint age = (test_mark->has_displaced_mark_helper() /* o->has_displaced_mark() */) ?
test_mark->displaced_mark_helper()->age() : test_mark->age();
if (!promote_immediately) {
// Try allocating obj in to-space (unless too old)
if (age < PSScavenge::tenuring_threshold()) {
new_obj = (oop) _young_lab.allocate(new_obj_size);
if (new_obj == NULL && !_young_gen_is_full) {
// Do we allocate directly, or flush and refill?
if (new_obj_size > (YoungPLABSize / 2)) {
// Allocate this object directly
new_obj = (oop)young_space()->cas_allocate(new_obj_size);
promotion_trace_event(new_obj, o, new_obj_size, age, false, NULL);
} else {
// Flush and fill
_young_lab.flush();
HeapWord* lab_base = young_space()->cas_allocate(YoungPLABSize);
if (lab_base != NULL) {
_young_lab.initialize(MemRegion(lab_base, YoungPLABSize));
// Try the young lab allocation again.
new_obj = (oop) _young_lab.allocate(new_obj_size);
promotion_trace_event(new_obj, o, new_obj_size, age, false, &_young_lab);
} else {
_young_gen_is_full = true;
}
}
}
}
}
// Otherwise try allocating obj tenured
if (new_obj == NULL) {
#ifndef PRODUCT
if (ParallelScavengeHeap::heap()->promotion_should_fail()) {
return oop_promotion_failed(o, test_mark);
}
#endif // #ifndef PRODUCT
new_obj = (oop) _old_lab.allocate(new_obj_size);
new_obj_is_tenured = true;
if (new_obj == NULL) {
if (!_old_gen_is_full) {
// Do we allocate directly, or flush and refill?
if (new_obj_size > (OldPLABSize / 2)) {
// Allocate this object directly
new_obj = (oop)old_gen()->cas_allocate(new_obj_size);
promotion_trace_event(new_obj, o, new_obj_size, age, true, NULL);
} else {
// Flush and fill
_old_lab.flush();
HeapWord* lab_base = old_gen()->cas_allocate(OldPLABSize);
if(lab_base != NULL) {
#ifdef ASSERT
// Delay the initialization of the promotion lab (plab).
// This exposes uninitialized plabs to card table processing.
if (GCWorkerDelayMillis > 0) {
os::sleep(Thread::current(), GCWorkerDelayMillis, false);
}
#endif
_old_lab.initialize(MemRegion(lab_base, OldPLABSize));
// Try the old lab allocation again.
new_obj = (oop) _old_lab.allocate(new_obj_size);
promotion_trace_event(new_obj, o, new_obj_size, age, true, &_old_lab);
}
}
}
// This is the promotion failed test, and code handling.
// The code belongs here for two reasons. It is slightly
// different than the code below, and cannot share the
// CAS testing code. Keeping the code here also minimizes
// the impact on the common case fast path code.
if (new_obj == NULL) {
_old_gen_is_full = true;
return oop_promotion_failed(o, test_mark);
}
}
}
assert(new_obj != NULL, "allocation should have succeeded");
// Copy obj
Copy::aligned_disjoint_words((HeapWord*)o, (HeapWord*)new_obj, new_obj_size);
// Now we have to CAS in the header.
if (o->cas_forward_to(new_obj, test_mark)) {
// We won any races, we "own" this object.
assert(new_obj == o->forwardee(), "Sanity");
// Increment age if obj still in new generation. Now that
// we're dealing with a markOop that cannot change, it is
// okay to use the non mt safe oop methods.
if (!new_obj_is_tenured) {
new_obj->incr_age();
assert(young_space()->contains(new_obj), "Attempt to push non-promoted obj");
}
// Do the size comparison first with new_obj_size, which we
// already have. Hopefully, only a few objects are larger than
// _min_array_size_for_chunking, and most of them will be arrays.
// So, the is->objArray() test would be very infrequent.
if (new_obj_size > _min_array_size_for_chunking &&
new_obj->is_objArray() &&
PSChunkLargeArrays) {
// we'll chunk it
oop* const masked_o = mask_chunked_array_oop(o);
push_depth(masked_o);
TASKQUEUE_STATS_ONLY(++_arrays_chunked; ++_masked_pushes);
} else {
// <original comment>
// The original idea here was to coalesce evacuated and dead objects.
// However that caused complications with the block offset table (BOT).
// In particular if there were two TLABs, one of them partially refined.
// |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~|
// The BOT entries of the unrefined part of TLAB_2 point to the start
// of TLAB_2. If the last object of the TLAB_1 and the first object
// of TLAB_2 are coalesced, then the cards of the unrefined part
// would point into middle of the filler object.
// The current approach is to not coalesce and leave the BOT contents intact.
// </original comment>
//
// We now reset the BOT when we start the object iteration over the
// region and refine its entries for every object we come across. So
// the above comment is not really relevant and we should be able
// to coalesce dead objects if we want to.
void do_object(oop obj) {
HeapWord* obj_addr = (HeapWord*) obj;
assert(_hr->is_in(obj_addr), "sanity");
size_t obj_size = obj->size();
HeapWord* obj_end = obj_addr + obj_size;
if (_end_of_last_gap != obj_addr) {
// there was a gap before obj_addr
_last_gap_threshold = _hr->cross_threshold(_end_of_last_gap, obj_addr);
}
if (obj->is_forwarded() && obj->forwardee() == obj) {
// The object failed to move.
// We consider all objects that we find self-forwarded to be
// live. What we'll do is that we'll update the prev marking
// info so that they are all under PTAMS and explicitly marked.
if (!_cm->isPrevMarked(obj)) {
_cm->markPrev(obj);
}
if (_during_initial_mark) {
// For the next marking info we'll only mark the
// self-forwarded objects explicitly if we are during
// initial-mark (since, normally, we only mark objects pointed
// to by roots if we succeed in copying them). By marking all
// self-forwarded objects we ensure that we mark any that are
// still pointed to be roots. During concurrent marking, and
// after initial-mark, we don't need to mark any objects
// explicitly and all objects in the CSet are considered
// (implicitly) live. So, we won't mark them explicitly and
// we'll leave them over NTAMS.
_cm->grayRoot(obj, obj_size, _worker_id, _hr);
}
_marked_bytes += (obj_size * HeapWordSize);
obj->set_mark(markOopDesc::prototype());
// While we were processing RSet buffers during the collection,
// we actually didn't scan any cards on the collection set,
// since we didn't want to update remembered sets with entries
// that point into the collection set, given that live objects
// from the collection set are about to move and such entries
// will be stale very soon.
// This change also dealt with a reliability issue which
// involved scanning a card in the collection set and coming
// across an array that was being chunked and looking malformed.
// The problem is that, if evacuation fails, we might have
// remembered set entries missing given that we skipped cards on
// the collection set. So, we'll recreate such entries now.
obj->oop_iterate(_update_rset_cl);
} else {
// The object has been either evacuated or is dead. Fill it with a
// dummy object.
MemRegion mr(obj_addr, obj_size);
CollectedHeap::fill_with_object(mr);
// must nuke all dead objects which we skipped when iterating over the region
_cm->clearRangePrevBitmap(MemRegion(_end_of_last_gap, obj_end));
}
_end_of_last_gap = obj_end;
_last_obj_threshold = _hr->cross_threshold(obj_addr, obj_end);
}
inline bool HRInto_G1RemSet::self_forwarded(oop obj) {
bool result = (obj->is_forwarded() && (obj->forwardee()== obj));
return result;
}
