src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp

rev 57380 : 8234974: Shenandoah: Do concurrent roots even when no evacuation is necessary

@@ -540,10 +540,11 @@
   if (is_update_refs_in_progress())          st->print("updating refs, ");
   if (is_concurrent_traversal_in_progress()) st->print("traversal, ");
   if (is_degenerated_gc_in_progress())       st->print("degenerated gc, ");
   if (is_full_gc_in_progress())              st->print("full gc, ");
   if (is_full_gc_move_in_progress())         st->print("full gc move, ");
+  if (is_concurrent_root_in_progress())      st->print("concurrent roots, ");
 
   if (cancelled_gc()) {
     st->print("cancelled");
   } else {
     st->print("not cancelled");

@@ -1538,10 +1539,15 @@
       heuristics()->choose_collection_set(_collection_set);
 
       _free_set->rebuild();
     }
 
+    if (!is_degenerated_gc_in_progress()) {
+      prepare_concurrent_roots();
+      prepare_concurrent_unloading();
+    }
+
     // If collection set has candidates, start evacuation.
     // Otherwise, bypass the rest of the cycle.
     if (!collection_set()->is_empty()) {
       ShenandoahGCPhase init_evac(ShenandoahPhaseTimings::init_evac);
 

@@ -1552,12 +1558,13 @@
       set_evacuation_in_progress(true);
       // From here on, we need to update references.
       set_has_forwarded_objects(true);
 
       if (!is_degenerated_gc_in_progress()) {
-        prepare_concurrent_roots();
-        prepare_concurrent_unloading();
+        if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
+          ShenandoahCodeRoots::arm_nmethods();
+        }
         evacuate_and_update_roots();
       }
 
       if (ShenandoahPacing) {
         pacer()->setup_for_evac();

@@ -1667,11 +1674,11 @@
     }
   }
 };
 
 void ShenandoahHeap::op_roots() {
-  if (is_evacuation_in_progress()) {
+  if (is_concurrent_root_in_progress()) {
     if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
       _unloader.unload();
     }
 
     if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {

@@ -2233,11 +2240,10 @@
 }
 
 void ShenandoahHeap::prepare_concurrent_unloading() {
   assert(SafepointSynchronize::is_at_safepoint(), "Must be at a safepoint");
   if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
-    ShenandoahCodeRoots::prepare_concurrent_unloading();
     _unloader.prepare();
   }
 }
 
 void ShenandoahHeap::finish_concurrent_unloading() {