--- old/src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.cpp	2019-12-11 23:05:19.893009903 +0100
+++ new/src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.cpp	2019-12-11 23:05:19.785009899 +0100
@@ -265,7 +265,12 @@
 
   ShenandoahMarkingContext* const marking_context = _heap->marking_context();
   if (_heap->is_concurrent_root_in_progress() && !marking_context->is_marked(obj)) {
-    return NULL;
+    Thread* thr = Thread::current();
+    if (thr->is_Java_thread()) {
+      return NULL;
+    } else {
+      return obj;
+    }
   }
 
   oop fwd = load_reference_barrier_not_null(obj);
--- old/src/hotspot/share/gc/shenandoah/shenandoahBarrierSetNMethod.cpp	2019-12-11 23:05:20.489009925 +0100
+++ new/src/hotspot/share/gc/shenandoah/shenandoahBarrierSetNMethod.cpp	2019-12-11 23:05:20.381009921 +0100
@@ -57,10 +57,8 @@
   }
 
   // Heal oops and disarm
-  if (ShenandoahHeap::heap()->is_evacuation_in_progress()) {
-    ShenandoahEvacOOMScope scope;
-    ShenandoahNMethod::heal_nmethod(nm);
-  }
+  ShenandoahEvacOOMScope scope;
+  ShenandoahNMethod::heal_nmethod(nm);
   ShenandoahNMethod::disarm_nmethod(nm);
   return true;
 }
--- old/src/hotspot/share/gc/shenandoah/shenandoahClosures.hpp	2019-12-11 23:05:21.076009947 +0100
+++ new/src/hotspot/share/gc/shenandoah/shenandoahClosures.hpp	2019-12-11 23:05:20.968009943 +0100
@@ -94,12 +94,13 @@
   inline void do_oop_work(T* p);
 };
 
-class ShenandoahEvacUpdateOopStorageRootsClosure : public BasicOopIterateClosure {
+class ShenandoahEvacUpdateCleanupRootsClosure : public BasicOopIterateClosure {
 private:
   ShenandoahHeap* _heap;
   Thread* _thread;
+  const ShenandoahMarkingContext* const _context;
 public:
-  inline ShenandoahEvacUpdateOopStorageRootsClosure();
+  inline ShenandoahEvacUpdateCleanupRootsClosure();
   inline void do_oop(oop* p);
   inline void do_oop(narrowOop* p);
 };
--- old/src/hotspot/share/gc/shenandoah/shenandoahClosures.inline.hpp	2019-12-11 23:05:21.667009969 +0100
+++ new/src/hotspot/share/gc/shenandoah/shenandoahClosures.inline.hpp	2019-12-11 23:05:21.562009965 +0100
@@ -135,29 +135,30 @@
   do_oop_work(p);
 }
 
-ShenandoahEvacUpdateOopStorageRootsClosure::ShenandoahEvacUpdateOopStorageRootsClosure() :
-  _heap(ShenandoahHeap::heap()), _thread(Thread::current()) {
+ShenandoahEvacUpdateCleanupRootsClosure::ShenandoahEvacUpdateCleanupRootsClosure() :
+  _heap(ShenandoahHeap::heap()), _thread(Thread::current()), _context(_heap->complete_marking_context()) {
 }
 
-void ShenandoahEvacUpdateOopStorageRootsClosure::do_oop(oop* p) {
+void ShenandoahEvacUpdateCleanupRootsClosure::do_oop(oop* p) {
   assert(_heap->is_concurrent_root_in_progress(), "Only do this when evacuation is in progress");
 
   oop obj = RawAccess<>::oop_load(p);
   if (! CompressedOops::is_null(obj)) {
-    if (_heap->in_collection_set(obj)) {
+    if (!_context->is_marked(obj)) {
+      Atomic::cmpxchg(p, obj, (oop)NULL);
+    } else if (_heap->in_collection_set(obj)) {
       assert(_heap->is_evacuation_in_progress(), "Only do this when evacuation is in progress");
       shenandoah_assert_marked(p, obj);
       oop resolved = ShenandoahBarrierSet::resolve_forwarded_not_null(obj);
       if (resolved == obj) {
         resolved = _heap->evacuate_object(obj, _thread);
       }
-
       Atomic::cmpxchg(p, obj, resolved);
     }
   }
 }
 
-void ShenandoahEvacUpdateOopStorageRootsClosure::do_oop(narrowOop* p) {
+void ShenandoahEvacUpdateCleanupRootsClosure::do_oop(narrowOop* p) {
   ShouldNotReachHere();
 }
 
--- old/src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp	2019-12-11 23:05:22.263009992 +0100
+++ new/src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp	2019-12-11 23:05:22.152009987 +0100
@@ -1555,6 +1555,10 @@
         verifier()->verify_before_evacuation();
       }
 
+      if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
+        ShenandoahCodeRoots::prepare_concurrent_unloading();
+      }
+
       set_evacuation_in_progress(true);
       // From here on, we need to update references.
       set_has_forwarded_objects(true);
@@ -1656,16 +1660,10 @@
 
   void work(uint worker_id) {
     ShenandoahEvacOOMScope oom;
+    ShenandoahEvacUpdateCleanupRootsClosure cl;
     {
-      // jni_roots and weak_roots are OopStorage backed roots, concurrent iteration
-      // may race against OopStorage::release() calls.
-      ShenandoahEvacUpdateOopStorageRootsClosure cl;
-      _vm_roots.oops_do<ShenandoahEvacUpdateOopStorageRootsClosure>(&cl);
-      _weak_roots.oops_do<ShenandoahEvacUpdateOopStorageRootsClosure>(&cl);
-    }
-
-    {
-      ShenandoahEvacuateUpdateRootsClosure cl;
+      _vm_roots.oops_do<>(&cl);
+      _weak_roots.oops_do<>(&cl);
       CLDToOopClosure clds(&cl, ClassLoaderData::_claim_strong);
       _cld_roots.cld_do(&clds);
     }
@@ -1674,14 +1672,13 @@
 
 void ShenandoahHeap::op_roots() {
   if (is_concurrent_root_in_progress()) {
-    if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
-      _unloader.unload();
-    }
-
-    if (ShenandoahConcurrentRoots::should_do_concurrent_roots() && is_concurrent_root_in_progress()) {
+    if (ShenandoahConcurrentRoots::should_do_concurrent_roots()) {
       ShenandoahConcurrentRootsEvacUpdateTask task;
       workers()->run_task(&task);
     }
+    if (ShenandoahConcurrentRoots::should_do_concurrent_class_unloading()) {
+      _unloader.unload();
+    }
   }
 
   set_concurrent_root_in_progress(false);
@@ -2239,7 +2236,6 @@
 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();
   }
 }