--- a/src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp	Thu Oct 17 20:56:04 2019 +0200
+++ b/src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp	Thu Oct 17 20:56:11 2019 +0200
@@ -1493,31 +1493,36 @@
 
     stop_concurrent_marking();
 
+    // All allocations past TAMS are implicitly live, adjust the region data.
+    // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
     {
       ShenandoahGCPhase phase(ShenandoahPhaseTimings::complete_liveness);
-
-      // All allocations past TAMS are implicitly live, adjust the region data.
-      // Bitmaps/TAMS are swapped at this point, so we need to poll complete bitmap.
       ShenandoahCompleteLivenessClosure cl;
       parallel_heap_region_iterate(&cl);
     }
 
+    // Force the threads to reacquire their TLABs outside the collection set.
+    {
+      ShenandoahGCPhase phase(ShenandoahPhaseTimings::retire_tlabs);
+      make_parsable(true);
+    }
+
+    // Trash the collection set left over from previous cycle, if any.
+    {
+      ShenandoahGCPhase phase(ShenandoahPhaseTimings::trash_cset);
+      trash_cset_regions();
+    }
+
     {
-      ShenandoahGCPhase prepare_evac(ShenandoahPhaseTimings::prepare_evac);
-
-      make_parsable(true);
-
-      trash_cset_regions();
-
-      {
-        ShenandoahHeapLocker locker(lock());
-        _collection_set->clear();
-        _free_set->clear();
-
-        heuristics()->choose_collection_set(_collection_set);
-
-        _free_set->rebuild();
-      }
+      ShenandoahGCPhase phase(ShenandoahPhaseTimings::prepare_evac);
+
+      ShenandoahHeapLocker locker(lock());
+      _collection_set->clear();
+      _free_set->clear();
+
+      heuristics()->choose_collection_set(_collection_set);
+
+      _free_set->rebuild();
     }
 
     // If collection set has candidates, start evacuation.
@@ -1580,7 +1585,10 @@
 
   set_evacuation_in_progress(false);
 
-  retire_and_reset_gclabs();
+  {
+    ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_evac_retire_gclabs);
+    retire_and_reset_gclabs();
+  }
 
   if (ShenandoahVerify) {
     verifier()->verify_after_evacuation();
@@ -2234,7 +2242,10 @@
 
   set_evacuation_in_progress(false);
 
-  retire_and_reset_gclabs();
+  {
+    ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_retire_gclabs);
+    retire_and_reset_gclabs();
+  }
 
   if (ShenandoahVerify) {
     if (!is_degenerated_gc_in_progress()) {
@@ -2244,15 +2255,20 @@
   }
 
   set_update_refs_in_progress(true);
-  make_parsable(true);
-  for (uint i = 0; i < num_regions(); i++) {
-    ShenandoahHeapRegion* r = get_region(i);
-    r->set_concurrent_iteration_safe_limit(r->top());
+
+  {
+    ShenandoahGCPhase phase(ShenandoahPhaseTimings::init_update_refs_prepare);
+
+    make_parsable(true);
+    for (uint i = 0; i < num_regions(); i++) {
+      ShenandoahHeapRegion* r = get_region(i);
+      r->set_concurrent_iteration_safe_limit(r->top());
+    }
+
+    // Reset iterator.
+    _update_refs_iterator.reset();
   }
 
-  // Reset iterator.
-  _update_refs_iterator.reset();
-
   if (ShenandoahPacing) {
     pacer()->setup_for_updaterefs();
   }
@@ -2263,7 +2279,7 @@
 
   // Check if there is left-over work, and finish it
   if (_update_refs_iterator.has_next()) {
-    ShenandoahGCPhase final_work(ShenandoahPhaseTimings::final_update_refs_finish_work);
+    ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_finish_work);
 
     // Finish updating references where we left off.
     clear_cancelled_gc();
@@ -2292,9 +2308,11 @@
     verifier()->verify_roots_in_to_space();
   }
 
-  ShenandoahGCPhase final_update_refs(ShenandoahPhaseTimings::final_update_refs_recycle);
-
-  trash_cset_regions();
+  {
+    ShenandoahGCPhase phase(ShenandoahPhaseTimings::final_update_refs_trash_cset);
+    trash_cset_regions();
+  }
+
   set_has_forwarded_objects(false);
   set_update_refs_in_progress(false);
 

--- a/src/hotspot/share/gc/shenandoah/shenandoahPhaseTimings.hpp	Thu Oct 17 20:56:04 2019 +0200
+++ b/src/hotspot/share/gc/shenandoah/shenandoahPhaseTimings.hpp	Thu Oct 17 20:56:11 2019 +0200
@@ -100,8 +100,9 @@
   f(purge_par,                                      "    Parallel Cleanup")             \
   f(purge_cldg,                                     "    CLDG")                         \
   f(complete_liveness,                              "  Complete Liveness")              \
+  f(retire_tlabs,                                   "  Retire TLABs")                   \
+  f(trash_cset,                                     "  Trash CSet")                     \
   f(prepare_evac,                                   "  Prepare Evacuation")             \
-  f(recycle_regions,                                "  Recycle regions")                \
                                                                                         \
   /* Per-thread timer block, should have "roots" counters in consistent order */        \
   f(init_evac,                                      "  Initial Evacuation")             \
@@ -127,9 +128,12 @@
                                                                                         \
   f(final_evac_gross,                               "Pause Final Evac (G)")             \
   f(final_evac,                                     "Pause Final Evac (N)")             \
+  f(final_evac_retire_gclabs,                       "  Retire GCLABs")                  \
                                                                                         \
   f(init_update_refs_gross,                         "Pause Init  Update Refs (G)")      \
   f(init_update_refs,                               "Pause Init  Update Refs (N)")      \
+  f(init_update_refs_retire_gclabs,                 "  Retire GCLABs")                  \
+  f(init_update_refs_prepare,                       "  Prepare")                        \
                                                                                         \
   f(final_update_refs_gross,                         "Pause Final Update Refs (G)")     \
   f(final_update_refs,                               "Pause Final Update Refs (N)")     \
@@ -157,7 +161,7 @@
   f(final_update_refs_string_dedup_queue_roots,      "    UR: Dedup Queue Roots")       \
   f(final_update_refs_finish_queues,                 "    UR: Finish Queues")           \
                                                                                         \
-  f(final_update_refs_recycle,                       "  Recycle")                       \
+  f(final_update_refs_trash_cset,                    "  Trash CSet")                    \
                                                                                         \
   f(degen_gc_gross,                                  "Pause Degenerated GC (G)")        \
   f(degen_gc,                                        "Pause Degenerated GC (N)")        \