void VM_G1CollectForAllocation::doit() {
G1CollectedHeap* g1h = G1CollectedHeap::heap();
GCCauseSetter x(g1h, _gc_cause);
_result = g1h->satisfy_failed_allocation(_word_size, allocation_context(), &_pause_succeeded);
assert(_result == NULL || _pause_succeeded,
"if we get back a result, the pause should have succeeded");
}
void HeapRegion::print_on(outputStream* st) const {
st->print("AC%4u", allocation_context());
st->print(" %2s", get_short_type_str());
if (in_collection_set())
st->print(" CS");
else
st->print(" ");
st->print(" TS %5d", _gc_time_stamp);
st->print(" PTAMS "PTR_FORMAT" NTAMS "PTR_FORMAT,
prev_top_at_mark_start(), next_top_at_mark_start());
G1OffsetTableContigSpace::print_on(st);
}
void G1AllocRegion::update_alloc_region(HeapRegion* alloc_region) {
trace("update");
// We explicitly check that the region is not empty to make sure we
// maintain the "the alloc region cannot be empty" invariant.
assert(alloc_region != NULL && !alloc_region->is_empty(),
ar_ext_msg(this, "pre-condition"));
_alloc_region = alloc_region;
_alloc_region->set_allocation_context(allocation_context());
_count += 1;
trace("updated");
}
void VM_G1IncCollectionPause::doit() {
G1CollectedHeap* g1h = G1CollectedHeap::heap();
assert(!_should_initiate_conc_mark || g1h->should_do_concurrent_full_gc(_gc_cause),
"only a GC locker, a System.gc(), stats update, whitebox, or a hum allocation induced GC should start a cycle");
if (_word_size > 0) {
// An allocation has been requested. So, try to do that first.
_result = g1h->attempt_allocation_at_safepoint(_word_size, allocation_context(),
false /* expect_null_cur_alloc_region */);
if (_result != NULL) {
// If we can successfully allocate before we actually do the
// pause then we will consider this pause successful.
_pause_succeeded = true;
return;
}
}
GCCauseSetter x(g1h, _gc_cause);
if (_should_initiate_conc_mark) {
// It's safer to read old_marking_cycles_completed() here, given
// that noone else will be updating it concurrently. Since we'll
// only need it if we're initiating a marking cycle, no point in
// setting it earlier.
_old_marking_cycles_completed_before = g1h->old_marking_cycles_completed();
// At this point we are supposed to start a concurrent cycle. We
// will do so if one is not already in progress.
bool res = g1h->g1_policy()->force_initial_mark_if_outside_cycle(_gc_cause);
// The above routine returns true if we were able to force the
// next GC pause to be an initial mark; it returns false if a
// marking cycle is already in progress.
//
// If a marking cycle is already in progress just return and skip the
// pause below - if the reason for requesting this initial mark pause
// was due to a System.gc() then the requesting thread should block in
// doit_epilogue() until the marking cycle is complete.
//
// If this initial mark pause was requested as part of a humongous
// allocation then we know that the marking cycle must just have
// been started by another thread (possibly also allocating a humongous
// object) as there was no active marking cycle when the requesting
// thread checked before calling collect() in
// attempt_allocation_humongous(). Retrying the GC, in this case,
// will cause the requesting thread to spin inside collect() until the
// just started marking cycle is complete - which may be a while. So
// we do NOT retry the GC.
if (!res) {
assert(_word_size == 0, "Concurrent Full GC/Humongous Object IM shouldn't be allocating");
if (_gc_cause != GCCause::_g1_humongous_allocation) {
_should_retry_gc = true;
}
return;
}
}
_pause_succeeded =
g1h->do_collection_pause_at_safepoint(_target_pause_time_ms);
if (_pause_succeeded && _word_size > 0) {
// An allocation had been requested.
_result = g1h->attempt_allocation_at_safepoint(_word_size, allocation_context(),
true /* expect_null_cur_alloc_region */);
} else {
assert(_result == NULL, "invariant");
if (!_pause_succeeded) {
// Another possible reason reason for the pause to not be successful
// is that, again, the GC locker is active (and has become active
// since the prologue was executed). In this case we should retry
// the pause after waiting for the GC locker to become inactive.
_should_retry_gc = true;
}
}
}
