8264026: Remove dependency between free collection set and eagerly reclaim humongous object tasks

Reviewed-by: sjohanss, ayang

Author: Thomas Schatzl

src/hotspot/share/gc/g1/g1CollectedHeap.cpp

@@ -3979,6 +3979,8 @@ void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_
 
   eagerly_reclaim_humongous_regions();
 
+  rebuild_free_region_list();
+
   record_obj_copy_mem_stats();
 
   evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
@@ -4330,21 +4332,17 @@ void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1Eva
   Ticks free_cset_end_time = Ticks::now();
   phase_times()->record_total_free_cset_time_ms((free_cset_end_time - free_cset_start_time).seconds() * 1000.0);
 
-  // Now rebuild the free region list.
-  _hrm.rebuild_free_list(workers());
-  phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - free_cset_end_time).seconds() * 1000.0);
-
   collection_set->clear();
 }
 
 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
- private:
+private:
   FreeRegionList* _free_region_list;
   HeapRegionSet* _proxy_set;
   uint _humongous_objects_reclaimed;
   uint _humongous_regions_reclaimed;
   size_t _freed_bytes;
- public:
+public:
 
   G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
     _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
@@ -4479,13 +4477,18 @@ void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
     }
   }
 
-  prepend_to_freelist(&local_cleanup_list);
   decrement_summary_bytes(cl.bytes_freed());
 
   phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
                                                        cl.humongous_objects_reclaimed());
 }
 
+void G1CollectedHeap::rebuild_free_region_list() {
+  Ticks start = Ticks::now();
+  _hrm.rebuild_free_list(workers());
+  phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - start).seconds() * 1000.0);
+}
+
 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
 public:
   virtual bool do_heap_region(HeapRegion* r) {

src/hotspot/share/gc/g1/g1CollectedHeap.hpp

@@ -172,6 +172,8 @@ class G1CollectedHeap : public CollectedHeap {
   HeapRegionSet _humongous_set;
 
   void eagerly_reclaim_humongous_regions();
+
+  void rebuild_free_region_list();
   // Start a new incremental collection set for the next pause.
   void start_new_collection_set();