--- a/src/hotspot/share/gc/g1/g1CollectedHeap.cpp Tue Aug 21 13:17:29 2018 -0700
+++ b/src/hotspot/share/gc/g1/g1CollectedHeap.cpp Tue Aug 21 20:29:57 2018 -0400
@@ -70,6 +70,7 @@
#include "gc/shared/generationSpec.hpp"
#include "gc/shared/isGCActiveMark.hpp"
#include "gc/shared/oopStorageParState.hpp"
+#include "gc/shared/parallelCleaning.hpp"
#include "gc/shared/preservedMarks.inline.hpp"
#include "gc/shared/suspendibleThreadSet.hpp"
#include "gc/shared/referenceProcessor.inline.hpp"
@@ -3254,334 +3255,12 @@
undo_waste * HeapWordSize / K);
}
-class G1StringCleaningTask : public AbstractGangTask {
-private:
- BoolObjectClosure* _is_alive;
- G1StringDedupUnlinkOrOopsDoClosure _dedup_closure;
- OopStorage::ParState<false /* concurrent */, false /* const */> _par_state_string;
-
- int _initial_string_table_size;
-
- bool _process_strings;
- int _strings_processed;
- int _strings_removed;
-
- bool _process_string_dedup;
-
-public:
- G1StringCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_string_dedup) :
- AbstractGangTask("String Unlinking"),
- _is_alive(is_alive),
- _dedup_closure(is_alive, NULL, false),
- _par_state_string(StringTable::weak_storage()),
- _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
- _process_string_dedup(process_string_dedup) {
-
- _initial_string_table_size = (int) StringTable::the_table()->table_size();
- if (process_strings) {
- StringTable::reset_dead_counter();
- }
- }
-
- ~G1StringCleaningTask() {
- log_info(gc, stringtable)(
- "Cleaned string table, "
- "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
- strings_processed(), strings_removed());
- if (_process_strings) {
- StringTable::finish_dead_counter();
- }
- }
-
- void work(uint worker_id) {
- int strings_processed = 0;
- int strings_removed = 0;
- if (_process_strings) {
- StringTable::possibly_parallel_unlink(&_par_state_string, _is_alive, &strings_processed, &strings_removed);
- Atomic::add(strings_processed, &_strings_processed);
- Atomic::add(strings_removed, &_strings_removed);
- }
- if (_process_string_dedup) {
- G1StringDedup::parallel_unlink(&_dedup_closure, worker_id);
- }
- }
-
- size_t strings_processed() const { return (size_t)_strings_processed; }
- size_t strings_removed() const { return (size_t)_strings_removed; }
-};
-
-class G1CodeCacheUnloadingTask {
-private:
- static Monitor* _lock;
-
- BoolObjectClosure* const _is_alive;
- const bool _unloading_occurred;
- const uint _num_workers;
-
- // Variables used to claim nmethods.
- CompiledMethod* _first_nmethod;
- CompiledMethod* volatile _claimed_nmethod;
-
- // The list of nmethods that need to be processed by the second pass.
- CompiledMethod* volatile _postponed_list;
- volatile uint _num_entered_barrier;
-
- public:
- G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
- _is_alive(is_alive),
- _unloading_occurred(unloading_occurred),
- _num_workers(num_workers),
- _first_nmethod(NULL),
- _claimed_nmethod(NULL),
- _postponed_list(NULL),
- _num_entered_barrier(0)
- {
- CompiledMethod::increase_unloading_clock();
- // Get first alive nmethod
- CompiledMethodIterator iter = CompiledMethodIterator();
- if(iter.next_alive()) {
- _first_nmethod = iter.method();
- }
- _claimed_nmethod = _first_nmethod;
- }
-
- ~G1CodeCacheUnloadingTask() {
- CodeCache::verify_clean_inline_caches();
-
- CodeCache::set_needs_cache_clean(false);
- guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
-
- CodeCache::verify_icholder_relocations();
- }
-
- private:
- void add_to_postponed_list(CompiledMethod* nm) {
- CompiledMethod* old;
- do {
- old = _postponed_list;
- nm->set_unloading_next(old);
- } while (Atomic::cmpxchg(nm, &_postponed_list, old) != old);
- }
-
- void clean_nmethod(CompiledMethod* nm) {
- bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
-
- if (postponed) {
- // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
- add_to_postponed_list(nm);
- }
-
- // Mark that this nmethod has been cleaned/unloaded.
- // After this call, it will be safe to ask if this nmethod was unloaded or not.
- nm->set_unloading_clock(CompiledMethod::global_unloading_clock());
- }
-
- void clean_nmethod_postponed(CompiledMethod* nm) {
- nm->do_unloading_parallel_postponed();
- }
-
- static const int MaxClaimNmethods = 16;
-
- void claim_nmethods(CompiledMethod** claimed_nmethods, int *num_claimed_nmethods) {
- CompiledMethod* first;
- CompiledMethodIterator last;
-
- do {
- *num_claimed_nmethods = 0;
-
- first = _claimed_nmethod;
- last = CompiledMethodIterator(first);
-
- if (first != NULL) {
-
- for (int i = 0; i < MaxClaimNmethods; i++) {
- if (!last.next_alive()) {
- break;
- }
- claimed_nmethods[i] = last.method();
- (*num_claimed_nmethods)++;
- }
- }
-
- } while (Atomic::cmpxchg(last.method(), &_claimed_nmethod, first) != first);
- }
-
- CompiledMethod* claim_postponed_nmethod() {
- CompiledMethod* claim;
- CompiledMethod* next;
-
- do {
- claim = _postponed_list;
- if (claim == NULL) {
- return NULL;
- }
-
- next = claim->unloading_next();
-
- } while (Atomic::cmpxchg(next, &_postponed_list, claim) != claim);
-
- return claim;
- }
-
- public:
- // Mark that we're done with the first pass of nmethod cleaning.
- void barrier_mark(uint worker_id) {
- MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
- _num_entered_barrier++;
- if (_num_entered_barrier == _num_workers) {
- ml.notify_all();
- }
- }
-
- // See if we have to wait for the other workers to
- // finish their first-pass nmethod cleaning work.
- void barrier_wait(uint worker_id) {
- if (_num_entered_barrier < _num_workers) {
- MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
- while (_num_entered_barrier < _num_workers) {
- ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
- }
- }
- }
-
- // Cleaning and unloading of nmethods. Some work has to be postponed
- // to the second pass, when we know which nmethods survive.
- void work_first_pass(uint worker_id) {
- // The first nmethods is claimed by the first worker.
- if (worker_id == 0 && _first_nmethod != NULL) {
- clean_nmethod(_first_nmethod);
- _first_nmethod = NULL;
- }
-
- int num_claimed_nmethods;
- CompiledMethod* claimed_nmethods[MaxClaimNmethods];
-
- while (true) {
- claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
-
- if (num_claimed_nmethods == 0) {
- break;
- }
-
- for (int i = 0; i < num_claimed_nmethods; i++) {
- clean_nmethod(claimed_nmethods[i]);
- }
- }
- }
-
- void work_second_pass(uint worker_id) {
- CompiledMethod* nm;
- // Take care of postponed nmethods.
- while ((nm = claim_postponed_nmethod()) != NULL) {
- clean_nmethod_postponed(nm);
- }
- }
-};
-
-Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
-
-class G1KlassCleaningTask : public StackObj {
- volatile int _clean_klass_tree_claimed;
- ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
-
- public:
- G1KlassCleaningTask() :
- _clean_klass_tree_claimed(0),
- _klass_iterator() {
- }
-
- private:
- bool claim_clean_klass_tree_task() {
- if (_clean_klass_tree_claimed) {
- return false;
- }
-
- return Atomic::cmpxchg(1, &_clean_klass_tree_claimed, 0) == 0;
- }
-
- InstanceKlass* claim_next_klass() {
- Klass* klass;
- do {
- klass =_klass_iterator.next_klass();
- } while (klass != NULL && !klass->is_instance_klass());
-
- // this can be null so don't call InstanceKlass::cast
- return static_cast<InstanceKlass*>(klass);
- }
-
-public:
-
- void clean_klass(InstanceKlass* ik) {
- ik->clean_weak_instanceklass_links();
- }
-
- void work() {
- ResourceMark rm;
-
- // One worker will clean the subklass/sibling klass tree.
- if (claim_clean_klass_tree_task()) {
- Klass::clean_subklass_tree();
- }
-
- // All workers will help cleaning the classes,
- InstanceKlass* klass;
- while ((klass = claim_next_klass()) != NULL) {
- clean_klass(klass);
- }
- }
-};
-
-// To minimize the remark pause times, the tasks below are done in parallel.
-class G1ParallelCleaningTask : public AbstractGangTask {
-private:
- bool _unloading_occurred;
- G1StringCleaningTask _string_task;
- G1CodeCacheUnloadingTask _code_cache_task;
- G1KlassCleaningTask _klass_cleaning_task;
-
-public:
- // The constructor is run in the VMThread.
- G1ParallelCleaningTask(BoolObjectClosure* is_alive, uint num_workers, bool unloading_occurred) :
- AbstractGangTask("Parallel Cleaning"),
- _unloading_occurred(unloading_occurred),
- _string_task(is_alive, true, G1StringDedup::is_enabled()),
- _code_cache_task(num_workers, is_alive, unloading_occurred),
- _klass_cleaning_task() {
- }
-
- // The parallel work done by all worker threads.
- void work(uint worker_id) {
- // Do first pass of code cache cleaning.
- _code_cache_task.work_first_pass(worker_id);
-
- // Let the threads mark that the first pass is done.
- _code_cache_task.barrier_mark(worker_id);
-
- // Clean the Strings.
- _string_task.work(worker_id);
-
- // Wait for all workers to finish the first code cache cleaning pass.
- _code_cache_task.barrier_wait(worker_id);
-
- // Do the second code cache cleaning work, which realize on
- // the liveness information gathered during the first pass.
- _code_cache_task.work_second_pass(worker_id);
-
- // Clean all klasses that were not unloaded.
- // The weak metadata in klass doesn't need to be
- // processed if there was no unloading.
- if (_unloading_occurred) {
- _klass_cleaning_task.work();
- }
- }
-};
-
-
void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
bool class_unloading_occurred) {
uint n_workers = workers()->active_workers();
- G1ParallelCleaningTask g1_unlink_task(is_alive, n_workers, class_unloading_occurred);
+ G1StringDedupUnlinkOrOopsDoClosure dedup_closure(is_alive, NULL, false);
+ ParallelCleaningTask g1_unlink_task(is_alive, &dedup_closure, n_workers, class_unloading_occurred);
workers()->run_task(&g1_unlink_task);
}
@@ -3593,7 +3272,8 @@
return;
}
- G1StringCleaningTask g1_unlink_task(is_alive, process_strings, process_string_dedup);
+ G1StringDedupUnlinkOrOopsDoClosure dedup_closure(is_alive, NULL, false);
+ StringCleaningTask g1_unlink_task(is_alive, process_string_dedup ? &dedup_closure : NULL, process_strings);
workers()->run_task(&g1_unlink_task);
}