changeset 50585:9d17c375dc30

8202017: Merge Reference Enqueuing phase with phase 3 of Reference processing Summary: Do reference enqueuing work directly in phase 3 after every Reference. Reviewed-by: kbarrett, sangheki
author tschatzl
date Tue, 08 May 2018 10:01:29 +0200
parents 1c4fb292447c
children 0d4920ac269c
files src/hotspot/share/gc/cms/concurrentMarkSweepGeneration.cpp src/hotspot/share/gc/cms/parNewGeneration.cpp src/hotspot/share/gc/g1/g1CollectedHeap.cpp src/hotspot/share/gc/g1/g1CollectedHeap.hpp src/hotspot/share/gc/g1/g1ConcurrentMark.cpp src/hotspot/share/gc/g1/g1FullGCReferenceProcessorExecutor.cpp src/hotspot/share/gc/g1/g1GCPhaseTimes.cpp src/hotspot/share/gc/g1/g1GCPhaseTimes.hpp src/hotspot/share/gc/parallel/psMarkSweep.cpp src/hotspot/share/gc/parallel/psParallelCompact.cpp src/hotspot/share/gc/parallel/psScavenge.cpp src/hotspot/share/gc/shared/genCollectedHeap.cpp src/hotspot/share/gc/shared/referenceProcessor.cpp src/hotspot/share/gc/shared/referenceProcessor.hpp src/hotspot/share/gc/shared/referenceProcessorPhaseTimes.cpp src/hotspot/share/gc/shared/referenceProcessorPhaseTimes.hpp test/hotspot/jtreg/gc/g1/TestGCLogMessages.java test/hotspot/jtreg/gc/logging/TestPrintReferences.java
diffstat 18 files changed, 48 insertions(+), 280 deletions(-) [+]
line wrap: on
line diff
--- a/src/hotspot/share/gc/cms/concurrentMarkSweepGeneration.cpp	Tue May 08 09:57:45 2018 +0200
+++ b/src/hotspot/share/gc/cms/concurrentMarkSweepGeneration.cpp	Tue May 08 10:01:29 2018 +0200
@@ -5254,16 +5254,7 @@
   restore_preserved_marks_if_any();  // done single-threaded for now
 
   rp->set_enqueuing_is_done(true);
-  if (rp->processing_is_mt()) {
-    rp->balance_all_queues();
-    CMSRefProcTaskExecutor task_executor(*this);
-    rp->enqueue_discovered_references(&task_executor, &pt);
-  } else {
-    rp->enqueue_discovered_references(NULL, &pt);
-  }
   rp->verify_no_references_recorded();
-  pt.print_enqueue_phase();
-  assert(!rp->discovery_enabled(), "should have been disabled");
 }
 
 #ifndef PRODUCT
--- a/src/hotspot/share/gc/cms/parNewGeneration.cpp	Tue May 08 09:57:45 2018 +0200
+++ b/src/hotspot/share/gc/cms/parNewGeneration.cpp	Tue May 08 10:01:29 2018 +0200
@@ -1054,18 +1054,10 @@
   update_time_of_last_gc(now);
 
   rp->set_enqueuing_is_done(true);
-  if (rp->processing_is_mt()) {
-    ParNewRefProcTaskExecutor task_executor(*this, *_old_gen, thread_state_set);
-    rp->enqueue_discovered_references(&task_executor, &pt);
-  } else {
-    rp->enqueue_discovered_references(NULL, &pt);
-  }
   rp->verify_no_references_recorded();
 
   gch->trace_heap_after_gc(gc_tracer());
 
-  pt.print_enqueue_phase();
-
   _gc_timer->register_gc_end();
 
   _gc_tracer.report_gc_end(_gc_timer->gc_end(), _gc_timer->time_partitions());
--- a/src/hotspot/share/gc/g1/g1CollectedHeap.cpp	Tue May 08 09:57:45 2018 +0200
+++ b/src/hotspot/share/gc/g1/g1CollectedHeap.cpp	Tue May 08 10:01:29 2018 +0200
@@ -3879,7 +3879,6 @@
 
 // End of weak reference support closures
 
-// Weak Reference processing during an evacuation pause (part 1).
 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
   double ref_proc_start = os::elapsedTime();
 
@@ -3939,42 +3938,15 @@
   // We have completed copying any necessary live referent objects.
   assert(pss->queue_is_empty(), "both queue and overflow should be empty");
 
+  make_pending_list_reachable();
+
+  rp->verify_no_references_recorded();
+
   double ref_proc_time = os::elapsedTime() - ref_proc_start;
   g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
 }
 
-// Weak Reference processing during an evacuation pause (part 2).
-void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
-  double ref_enq_start = os::elapsedTime();
-
-  ReferenceProcessor* rp = _ref_processor_stw;
-  assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
-
-  ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
-
-  // Now enqueue any remaining on the discovered lists on to
-  // the pending list.
-  if (!rp->processing_is_mt()) {
-    // Serial reference processing...
-    rp->enqueue_discovered_references(NULL, pt);
-  } else {
-    // Parallel reference enqueueing
-
-    uint n_workers = workers()->active_workers();
-
-    assert(n_workers <= rp->max_num_queues(),
-           "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
-           n_workers,  rp->max_num_queues());
-
-    G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
-    rp->enqueue_discovered_references(&par_task_executor, pt);
-  }
-
-  rp->verify_no_references_recorded();
-  assert(!rp->discovery_enabled(), "should have been disabled");
-
-  // If during an initial mark pause we install a pending list head which is not otherwise reachable
-  // ensure that it is marked in the bitmap for concurrent marking to discover.
+void G1CollectedHeap::make_pending_list_reachable() {
   if (collector_state()->in_initial_mark_gc()) {
     oop pll_head = Universe::reference_pending_list();
     if (pll_head != NULL) {
@@ -3982,14 +3954,6 @@
       _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
     }
   }
-
-  // FIXME
-  // CM's reference processing also cleans up the string and symbol tables.
-  // Should we do that here also? We could, but it is a serial operation
-  // and could significantly increase the pause time.
-
-  double ref_enq_time = os::elapsedTime() - ref_enq_start;
-  g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
 }
 
 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
@@ -4069,7 +4033,11 @@
   // objects (and their reachable sub-graphs) that were
   // not copied during the pause.
   process_discovered_references(per_thread_states);
-  enqueue_discovered_references(per_thread_states);
+
+  // FIXME
+  // CM's reference processing also cleans up the string and symbol tables.
+  // Should we do that here also? We could, but it is a serial operation
+  // and could significantly increase the pause time.
 
   G1STWIsAliveClosure is_alive(this);
   G1KeepAliveClosure keep_alive(this);
--- a/src/hotspot/share/gc/g1/g1CollectedHeap.hpp	Tue May 08 09:57:45 2018 +0200
+++ b/src/hotspot/share/gc/g1/g1CollectedHeap.hpp	Tue May 08 10:01:29 2018 +0200
@@ -513,13 +513,13 @@
   // allocated block, or else "NULL".
   HeapWord* expand_and_allocate(size_t word_size);
 
-  // Process any reference objects discovered during
-  // an incremental evacuation pause.
+  // Process any reference objects discovered.
   void process_discovered_references(G1ParScanThreadStateSet* per_thread_states);
 
-  // Enqueue any remaining discovered references
-  // after processing.
-  void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states);
+  // If during an initial mark pause we may install a pending list head which is not
+  // otherwise reachable ensure that it is marked in the bitmap for concurrent marking
+  // to discover.
+  void make_pending_list_reachable();
 
   // Merges the information gathered on a per-thread basis for all worker threads
   // during GC into global variables.
--- a/src/hotspot/share/gc/g1/g1ConcurrentMark.cpp	Tue May 08 09:57:45 2018 +0200
+++ b/src/hotspot/share/gc/g1/g1ConcurrentMark.cpp	Tue May 08 10:01:29 2018 +0200
@@ -1677,12 +1677,7 @@
 
     assert(rp->num_queues() == active_workers, "why not");
 
-    rp->enqueue_discovered_references(executor, &pt);
-
     rp->verify_no_references_recorded();
-
-    pt.print_enqueue_phase();
-
     assert(!rp->discovery_enabled(), "Post condition");
   }
 
--- a/src/hotspot/share/gc/g1/g1FullGCReferenceProcessorExecutor.cpp	Tue May 08 09:57:45 2018 +0200
+++ b/src/hotspot/share/gc/g1/g1FullGCReferenceProcessorExecutor.cpp	Tue May 08 10:01:29 2018 +0200
@@ -108,8 +108,4 @@
   pt.print_all_references();
 
   assert(marker->oop_stack()->is_empty(), "Should be no oops on the stack");
-
-  // Now enqueue the references.
-  _reference_processor->enqueue_discovered_references(executor, &pt);
-  pt.print_enqueue_phase();
 }
--- a/src/hotspot/share/gc/g1/g1GCPhaseTimes.cpp	Tue May 08 09:57:45 2018 +0200
+++ b/src/hotspot/share/gc/g1/g1GCPhaseTimes.cpp	Tue May 08 10:01:29 2018 +0200
@@ -129,7 +129,6 @@
   _cur_clear_ct_time_ms = 0.0;
   _cur_expand_heap_time_ms = 0.0;
   _cur_ref_proc_time_ms = 0.0;
-  _cur_ref_enq_time_ms = 0.0;
   _cur_weak_ref_proc_time_ms = 0.0;
   _cur_collection_start_sec = 0.0;
   _root_region_scan_wait_time_ms = 0.0;
@@ -383,7 +382,6 @@
                         _recorded_preserve_cm_referents_time_ms +
                         _cur_ref_proc_time_ms +
                         _cur_weak_ref_proc_time_ms +
-                        _cur_ref_enq_time_ms +
                         _cur_clear_ct_time_ms +
                         _recorded_merge_pss_time_ms +
                         _cur_strong_code_root_purge_time_ms +
@@ -416,9 +414,6 @@
     trace_time("Remove Self Forwards",_cur_evac_fail_remove_self_forwards);
   }
 
-  debug_time_for_reference("Reference Enqueuing", _cur_ref_enq_time_ms);
-  _ref_phase_times.print_enqueue_phase(2, false);
-
   debug_time("Merge Per-Thread State", _recorded_merge_pss_time_ms);
   debug_time("Code Roots Purge", _cur_strong_code_root_purge_time_ms);
 
--- a/src/hotspot/share/gc/g1/g1GCPhaseTimes.hpp	Tue May 08 09:57:45 2018 +0200
+++ b/src/hotspot/share/gc/g1/g1GCPhaseTimes.hpp	Tue May 08 10:01:29 2018 +0200
@@ -261,10 +261,6 @@
     _cur_weak_ref_proc_time_ms = ms;
   }
 
-  void record_ref_enq_time(double ms) {
-    _cur_ref_enq_time_ms = ms;
-  }
-
   void record_root_region_scan_wait_time(double time_ms) {
     _root_region_scan_wait_time_ms = time_ms;
   }
--- a/src/hotspot/share/gc/parallel/psMarkSweep.cpp	Tue May 08 09:57:45 2018 +0200
+++ b/src/hotspot/share/gc/parallel/psMarkSweep.cpp	Tue May 08 10:01:29 2018 +0200
@@ -260,11 +260,7 @@
     DerivedPointerTable::update_pointers();
 #endif
 
-    ReferenceProcessorPhaseTimes pt(_gc_timer, ref_processor()->num_queues());
-
-    ref_processor()->enqueue_discovered_references(NULL, &pt);
-
-    pt.print_enqueue_phase();
+    assert(!ref_processor()->discovery_enabled(), "Should have been disabled earlier");
 
     // Update time of last GC
     reset_millis_since_last_gc();
--- a/src/hotspot/share/gc/parallel/psParallelCompact.cpp	Tue May 08 09:57:45 2018 +0200
+++ b/src/hotspot/share/gc/parallel/psParallelCompact.cpp	Tue May 08 10:01:29 2018 +0200
@@ -1038,12 +1038,6 @@
   DerivedPointerTable::update_pointers();
 #endif
 
-  ReferenceProcessorPhaseTimes pt(&_gc_timer, ref_processor()->num_queues());
-
-  ref_processor()->enqueue_discovered_references(NULL, &pt);
-
-  pt.print_enqueue_phase();
-
   if (ZapUnusedHeapArea) {
     heap->gen_mangle_unused_area();
   }
--- a/src/hotspot/share/gc/parallel/psScavenge.cpp	Tue May 08 09:57:45 2018 +0200
+++ b/src/hotspot/share/gc/parallel/psScavenge.cpp	Tue May 08 10:01:29 2018 +0200
@@ -430,16 +430,6 @@
 
       _gc_tracer.report_gc_reference_stats(stats);
       pt.print_all_references();
-
-      // Enqueue reference objects discovered during scavenge.
-      if (reference_processor()->processing_is_mt()) {
-        PSRefProcTaskExecutor task_executor;
-        reference_processor()->enqueue_discovered_references(&task_executor, &pt);
-      } else {
-        reference_processor()->enqueue_discovered_references(NULL, &pt);
-      }
-
-      pt.print_enqueue_phase();
     }
 
     assert(promotion_manager->stacks_empty(),"stacks should be empty at this point");
--- a/src/hotspot/share/gc/shared/genCollectedHeap.cpp	Tue May 08 09:57:45 2018 +0200
+++ b/src/hotspot/share/gc/shared/genCollectedHeap.cpp	Tue May 08 10:01:29 2018 +0200
@@ -517,9 +517,7 @@
     }
     gen->collect(full, clear_soft_refs, size, is_tlab);
     if (!rp->enqueuing_is_done()) {
-      ReferenceProcessorPhaseTimes pt(NULL, rp->num_queues());
-      rp->enqueue_discovered_references(NULL, &pt);
-      pt.print_enqueue_phase();
+      rp->disable_discovery();
     } else {
       rp->set_enqueuing_is_done(false);
     }
--- a/src/hotspot/share/gc/shared/referenceProcessor.cpp	Tue May 08 09:57:45 2018 +0200
+++ b/src/hotspot/share/gc/shared/referenceProcessor.cpp	Tue May 08 10:01:29 2018 +0200
@@ -257,113 +257,6 @@
   return stats;
 }
 
-void ReferenceProcessor::enqueue_discovered_references(AbstractRefProcTaskExecutor*  task_executor,
-                                                       ReferenceProcessorPhaseTimes* phase_times) {
-  // Enqueue references that are not made active again, and
-  // clear the decks for the next collection (cycle).
-  enqueue_discovered_reflists(task_executor, phase_times);
-
-  // Stop treating discovered references specially.
-  disable_discovery();
-}
-
-void ReferenceProcessor::enqueue_discovered_reflist(DiscoveredList& refs_list) {
-  // Given a list of refs linked through the "discovered" field
-  // (java.lang.ref.Reference.discovered), self-loop their "next" field
-  // thus distinguishing them from active References, then
-  // prepend them to the pending list.
-  //
-  // The Java threads will see the Reference objects linked together through
-  // the discovered field. Instead of trying to do the write barrier updates
-  // in all places in the reference processor where we manipulate the discovered
-  // field we make sure to do the barrier here where we anyway iterate through
-  // all linked Reference objects. Note that it is important to not dirty any
-  // cards during reference processing since this will cause card table
-  // verification to fail for G1.
-  log_develop_trace(gc, ref)("ReferenceProcessor::enqueue_discovered_reflist list " INTPTR_FORMAT, p2i(&refs_list));
-
-  oop obj = NULL;
-  oop next_discovered = refs_list.head();
-  // Walk down the list, self-looping the next field
-  // so that the References are not considered active.
-  while (obj != next_discovered) {
-    obj = next_discovered;
-    assert(obj->is_instance(), "should be an instance object");
-    assert(InstanceKlass::cast(obj->klass())->is_reference_instance_klass(), "should be reference object");
-    next_discovered = java_lang_ref_Reference::discovered(obj);
-    log_develop_trace(gc, ref)("        obj " INTPTR_FORMAT "/next_discovered " INTPTR_FORMAT, p2i(obj), p2i(next_discovered));
-    assert(java_lang_ref_Reference::next(obj) == NULL,
-           "Reference not active; should not be discovered");
-    // Self-loop next, so as to make Ref not active.
-    java_lang_ref_Reference::set_next_raw(obj, obj);
-    if (next_discovered != obj) {
-      HeapAccess<AS_NO_KEEPALIVE>::oop_store_at(obj, java_lang_ref_Reference::discovered_offset, next_discovered);
-    } else {
-      // This is the last object.
-      // Swap refs_list into pending list and set obj's
-      // discovered to what we read from the pending list.
-      oop old = Universe::swap_reference_pending_list(refs_list.head());
-      HeapAccess<AS_NO_KEEPALIVE>::oop_store_at(obj, java_lang_ref_Reference::discovered_offset, old);
-    }
-  }
-}
-
-// Parallel enqueue task
-class RefProcEnqueueTask: public AbstractRefProcTaskExecutor::EnqueueTask {
-public:
-  RefProcEnqueueTask(ReferenceProcessor&           ref_processor,
-                     DiscoveredList                discovered_refs[],
-                     int                           n_queues,
-                     ReferenceProcessorPhaseTimes* phase_times)
-    : EnqueueTask(ref_processor, discovered_refs, n_queues, phase_times)
-  { }
-
-  virtual void work(unsigned int work_id) {
-    RefProcWorkerTimeTracker tt(ReferenceProcessorPhaseTimes::RefEnqueue, _phase_times, work_id);
-
-    assert(work_id < (unsigned int)_ref_processor.max_num_queues(), "Index out-of-bounds");
-    // Simplest first cut: static partitioning.
-    int index = work_id;
-    // The increment on "index" must correspond to the maximum number of queues
-    // (n_queues) with which that ReferenceProcessor was created.  That
-    // is because of the "clever" way the discovered references lists were
-    // allocated and are indexed into.
-    assert(_n_queues == (int) _ref_processor.max_num_queues(), "Different number not expected");
-    for (int j = 0;
-         j < ReferenceProcessor::number_of_subclasses_of_ref();
-         j++, index += _n_queues) {
-      _ref_processor.enqueue_discovered_reflist(_refs_lists[index]);
-      _refs_lists[index].set_head(NULL);
-      _refs_lists[index].set_length(0);
-    }
-  }
-};
-
-// Enqueue references that are not made active again
-void ReferenceProcessor::enqueue_discovered_reflists(AbstractRefProcTaskExecutor*  task_executor,
-                                                     ReferenceProcessorPhaseTimes* phase_times) {
-
-  ReferenceProcessorStats stats(total_count(_discoveredSoftRefs),
-                                total_count(_discoveredWeakRefs),
-                                total_count(_discoveredFinalRefs),
-                                total_count(_discoveredPhantomRefs));
-
-  RefProcEnqueueTimeTracker tt(phase_times, stats);
-
-  if (_processing_is_mt && task_executor != NULL) {
-    // Parallel code
-    RefProcEnqueueTask tsk(*this, _discovered_refs, _max_num_queues, phase_times);
-    task_executor->execute(tsk);
-  } else {
-    // Serial code: call the parent class's implementation
-    for (uint i = 0; i < _max_num_queues * number_of_subclasses_of_ref(); i++) {
-      enqueue_discovered_reflist(_discovered_refs[i]);
-      _discovered_refs[i].set_head(NULL);
-      _discovered_refs[i].set_length(0);
-    }
-  }
-}
-
 void DiscoveredListIterator::load_ptrs(DEBUG_ONLY(bool allow_null_referent)) {
   _current_discovered_addr = java_lang_ref_Reference::discovered_addr_raw(_current_discovered);
   oop discovered = java_lang_ref_Reference::discovered(_current_discovered);
@@ -409,6 +302,25 @@
   RawAccess<>::oop_store(_referent_addr, oop(NULL));
 }
 
+void DiscoveredListIterator::enqueue() {
+  // Self-loop next, so as to make Ref not active.
+  java_lang_ref_Reference::set_next_raw(_current_discovered, _current_discovered);
+
+  HeapAccess<AS_NO_KEEPALIVE>::oop_store_at(_current_discovered,
+                                            java_lang_ref_Reference::discovered_offset,
+                                            _next_discovered);
+}
+
+void DiscoveredListIterator::complete_enqeue() {
+  if (_prev_discovered != NULL) {
+    // This is the last object.
+    // Swap refs_list into pending list and set obj's
+    // discovered to what we read from the pending list.
+    oop old = Universe::swap_reference_pending_list(_refs_list.head());
+    HeapAccess<AS_NO_KEEPALIVE>::oop_store_at(_prev_discovered, java_lang_ref_Reference::discovered_offset, old);
+  }
+}
+
 // NOTE: process_phase*() are largely similar, and at a high level
 // merely iterate over the extant list applying a predicate to
 // each of its elements and possibly removing that element from the
@@ -556,13 +468,18 @@
       // keep the referent around
       iter.make_referent_alive();
     }
+    iter.enqueue();
     log_develop_trace(gc, ref)("Adding %sreference (" INTPTR_FORMAT ": %s) as pending",
                                clear_referent ? "cleared " : "", p2i(iter.obj()), iter.obj()->klass()->internal_name());
     assert(oopDesc::is_oop(iter.obj(), UseConcMarkSweepGC), "Adding a bad reference");
     iter.next();
   }
+  iter.complete_enqeue();
   // Close the reachable set
   complete_gc->do_void();
+  // Clear the list.
+  refs_list.set_head(NULL);
+  refs_list.set_length(0);
 }
 
 void
@@ -785,13 +702,6 @@
 #endif
 }
 
-void ReferenceProcessor::balance_all_queues() {
-  balance_queues(_discoveredSoftRefs);
-  balance_queues(_discoveredWeakRefs);
-  balance_queues(_discoveredFinalRefs);
-  balance_queues(_discoveredPhantomRefs);
-}
-
 void ReferenceProcessor::process_discovered_reflist(
   DiscoveredList                refs_lists[],
   ReferencePolicy*              policy,
--- a/src/hotspot/share/gc/shared/referenceProcessor.hpp	Tue May 08 09:57:45 2018 +0200
+++ b/src/hotspot/share/gc/shared/referenceProcessor.hpp	Tue May 08 10:01:29 2018 +0200
@@ -143,6 +143,12 @@
     }
   }
 
+  // Do enqueuing work, i.e. notifying the GC about the changed discovered pointers.
+  void enqueue();
+
+  // Move enqueued references to the reference pending list.
+  void complete_enqeue();
+
   // NULL out referent pointer.
   void clear_referent();
 
@@ -273,9 +279,6 @@
                       OopClosure*        keep_alive,
                       VoidClosure*       complete_gc);
 
-  // Enqueue references with a certain reachability level
-  void enqueue_discovered_reflist(DiscoveredList& refs_list);
-
   // "Preclean" all the discovered reference lists
   // by removing references with strongly reachable referents.
   // The first argument is a predicate on an oop that indicates
@@ -295,9 +298,6 @@
   // occupying the i / _num_queues slot.
   const char* list_name(uint i);
 
-  void enqueue_discovered_reflists(AbstractRefProcTaskExecutor* task_executor,
-                                   ReferenceProcessorPhaseTimes* phase_times);
-
   // "Preclean" the given discovered reference list
   // by removing references with strongly reachable referents.
   // Currently used in support of CMS only.
@@ -387,8 +387,6 @@
   // iterate over oops
   void weak_oops_do(OopClosure* f);       // weak roots
 
-  // Balance each of the discovered lists.
-  void balance_all_queues();
   void verify_list(DiscoveredList& ref_list);
 
   // Discover a Reference object, using appropriate discovery criteria
@@ -405,10 +403,6 @@
                                 AbstractRefProcTaskExecutor*  task_executor,
                                 ReferenceProcessorPhaseTimes* phase_times);
 
-  // Enqueue references at end of GC (called by the garbage collector)
-  void enqueue_discovered_references(AbstractRefProcTaskExecutor* task_executor,
-                                     ReferenceProcessorPhaseTimes* phase_times);
-
   // If a discovery is in process that is being superceded, abandon it: all
   // the discovered lists will be empty, and all the objects on them will
   // have NULL discovered fields.  Must be called only at a safepoint.
--- a/src/hotspot/share/gc/shared/referenceProcessorPhaseTimes.cpp	Tue May 08 09:57:45 2018 +0200
+++ b/src/hotspot/share/gc/shared/referenceProcessorPhaseTimes.cpp	Tue May 08 10:01:29 2018 +0200
@@ -78,8 +78,6 @@
     case ReferenceProcessorPhaseTimes::FinalRefPhase3:
     case ReferenceProcessorPhaseTimes::PhantomRefPhase3:
       return "Phase3";
-    case ReferenceProcessorPhaseTimes::RefEnqueue:
-      return "Reference Enqueuing";
     default:
       ShouldNotReachHere();
       return NULL;
@@ -191,21 +189,6 @@
   times->set_ref_cleared(ref_type, discovered - after_count);
 }
 
-RefProcEnqueueTimeTracker::RefProcEnqueueTimeTracker(ReferenceProcessorPhaseTimes* phase_times,
-                                                     ReferenceProcessorStats& stats) :
-  RefProcPhaseTimeBaseTracker("Reference Enqueuing", phase_times) {
-    phase_times->set_ref_enqueued(REF_SOFT, stats.soft_count());
-    phase_times->set_ref_enqueued(REF_WEAK, stats.weak_count());
-    phase_times->set_ref_enqueued(REF_FINAL, stats.final_count());
-    phase_times->set_ref_enqueued(REF_PHANTOM, stats.phantom_count());
-}
-
-RefProcEnqueueTimeTracker::~RefProcEnqueueTimeTracker() {
-  double elapsed = elapsed_time();
-
-  phase_times()->set_par_phase_time_ms(ReferenceProcessorPhaseTimes::RefEnqueue, elapsed);
-}
-
 ReferenceProcessorPhaseTimes::ReferenceProcessorPhaseTimes(GCTimer* gc_timer, uint max_gc_threads) :
   _gc_timer(gc_timer), _processing_is_mt(false) {
 
@@ -369,17 +352,6 @@
   return (RefProcParPhases)result;
 }
 
-void ReferenceProcessorPhaseTimes::print_enqueue_phase(uint base_indent, bool print_total) const {
-  if (print_total) {
-    print_phase(RefEnqueue, base_indent);
-  }
-
-  log_debug(gc, phases, ref)("%sReference Counts:  Soft: " SIZE_FORMAT "  Weak: " SIZE_FORMAT
-                             "  Final: " SIZE_FORMAT "  Phantom: " SIZE_FORMAT ,
-                             Indents[base_indent + 1], ref_enqueued(REF_SOFT), ref_enqueued(REF_WEAK),
-                             ref_enqueued(REF_FINAL), ref_enqueued(REF_PHANTOM));
-}
-
 #define TIME_FORMAT "%.1lfms"
 
 void ReferenceProcessorPhaseTimes::print_all_references(uint base_indent, bool print_total) const {
--- a/src/hotspot/share/gc/shared/referenceProcessorPhaseTimes.hpp	Tue May 08 09:57:45 2018 +0200
+++ b/src/hotspot/share/gc/shared/referenceProcessorPhaseTimes.hpp	Tue May 08 10:01:29 2018 +0200
@@ -46,7 +46,6 @@
     FinalRefPhase3,
     PhantomRefPhase2,
     PhantomRefPhase3,
-    RefEnqueue,
     RefParPhaseMax
   };
 
@@ -133,7 +132,6 @@
   // Reset all fields. If not reset at next cycle, an assertion will fail.
   void reset();
 
-  void print_enqueue_phase(uint base_indent = 0, bool print_total = true) const;
   void print_all_references(uint base_indent = 0, bool print_total = true) const;
 };
 
@@ -203,13 +201,4 @@
   ~RefProcPhaseTimesTracker();
 };
 
-// Updates enqueue time related information.
-// - Enqueueing time, enqueued reference count and stats for each working thread if MT processed.
-class RefProcEnqueueTimeTracker : public RefProcPhaseTimeBaseTracker {
-public:
-  RefProcEnqueueTimeTracker(ReferenceProcessorPhaseTimes* phase_times,
-                            ReferenceProcessorStats& stats);
-  ~RefProcEnqueueTimeTracker();
-};
-
 #endif // SHARE_VM_GC_SHARED_REFERENCEPROCESSORPHASETIMES_HPP
--- a/test/hotspot/jtreg/gc/g1/TestGCLogMessages.java	Tue May 08 09:57:45 2018 +0200
+++ b/test/hotspot/jtreg/gc/g1/TestGCLogMessages.java	Tue May 08 10:01:29 2018 +0200
@@ -141,7 +141,6 @@
         new LogMessageWithLevel("Resize TLABs", Level.DEBUG),
         // Reference Processing
         new LogMessageWithLevel("Reference Processing", Level.DEBUG),
-        new LogMessageWithLevel("Reference Enqueuing", Level.DEBUG),
         // VM internal reference processing
         new LogMessageWithLevel("Weak Processing", Level.DEBUG),
 
--- a/test/hotspot/jtreg/gc/logging/TestPrintReferences.java	Tue May 08 09:57:45 2018 +0200
+++ b/test/hotspot/jtreg/gc/logging/TestPrintReferences.java	Tue May 08 10:01:29 2018 +0200
@@ -93,9 +93,6 @@
                             gcLogTimeRegex + indent(8) + "Discovered: " + countRegex + "\n" +
                             gcLogTimeRegex + indent(8) + "Cleared: " + countRegex + "\n";
     String softRefDetailRegex = gcLogTimeRegex + indent(8) + phase1 + ": " + timeRegex + "\n" + refDetailRegex;
-    String enqueueRegex = gcLogTimeRegex + indent(4) + "Reference Enqueuing: " + timeRegex + "\n";
-    String enqueueDetailRegex = gcLogTimeRegex + indent(6) + "Reference Counts:  Soft: " + countRegex +
-                                "  Weak: " + countRegex + "  Final: " + countRegex + "  Phantom: " + countRegex + "\n";
 
     output.shouldMatch(/* Total Reference processing time */
                        totalRegex +
@@ -106,11 +103,7 @@
                        /* FinalReference processing */
                        finalRefRegex + balanceRegex + refDetailRegex +
                        /* PhantomReference processing */
-                       phantomRefRegex + balanceRegex + refDetailRegex +
-                       /* Total Enqueuing time */
-                       enqueueRegex +
-                         /* Enqueued Stats */
-                       enqueueDetailRegex
+                       phantomRefRegex + balanceRegex + refDetailRegex
                        );
   }