--- a/src/hotspot/share/gc/shenandoah/shenandoahTraversalGC.cpp	Fri May 17 12:33:37 2019 +0200
+++ b/src/hotspot/share/gc/shenandoah/shenandoahTraversalGC.cpp	Fri May 17 09:52:35 2019 -0400
@@ -161,11 +161,13 @@
 
 class ShenandoahInitTraversalCollectionTask : public AbstractGangTask {
 private:
-  ShenandoahRootProcessor* _rp;
+  ShenandoahRootScanner* _rp;
   ShenandoahHeap* _heap;
   ShenandoahCsetCodeRootsIterator* _cset_coderoots;
+  ShenandoahStringDedupRoots       _dedup_roots;
+
 public:
-  ShenandoahInitTraversalCollectionTask(ShenandoahRootProcessor* rp, ShenandoahCsetCodeRootsIterator* cset_coderoots) :
+  ShenandoahInitTraversalCollectionTask(ShenandoahRootScanner* rp, ShenandoahCsetCodeRootsIterator* cset_coderoots) :
     AbstractGangTask("Shenandoah Init Traversal Collection"),
     _rp(rp),
     _heap(ShenandoahHeap::heap()),
@@ -191,18 +193,17 @@
       ShenandoahMarkCLDClosure cld_cl(&roots_cl);
       MarkingCodeBlobClosure code_cl(&roots_cl, CodeBlobToOopClosure::FixRelocations);
       if (unload_classes) {
-        _rp->process_strong_roots(&roots_cl, &cld_cl, NULL, NULL, worker_id);
+        _rp->strong_roots_do(worker_id, &roots_cl);
         // Need to pre-evac code roots here. Otherwise we might see from-space constants.
         ShenandoahWorkerTimings* worker_times = _heap->phase_timings()->worker_times();
         ShenandoahWorkerTimingsTracker timer(worker_times, ShenandoahPhaseTimings::CodeCacheRoots, worker_id);
         _cset_coderoots->possibly_parallel_blobs_do(&code_cl);
       } else {
-        _rp->process_all_roots(&roots_cl, &cld_cl, &code_cl, NULL, worker_id);
+        _rp->roots_do(worker_id, &roots_cl, &cld_cl, &code_cl);
       }
-      if (ShenandoahStringDedup::is_enabled()) {
-        AlwaysTrueClosure is_alive;
-        ShenandoahStringDedup::parallel_oops_do(&is_alive, &roots_cl, worker_id);
-      }
+
+      AlwaysTrueClosure is_alive;
+      _dedup_roots.oops_do(&is_alive, &roots_cl, worker_id);
     }
   }
 };
@@ -230,11 +231,11 @@
 
 class ShenandoahFinalTraversalCollectionTask : public AbstractGangTask {
 private:
-  ShenandoahRootProcessor* _rp;
+  ShenandoahRootScanner* _rp;
   ShenandoahTaskTerminator* _terminator;
   ShenandoahHeap* _heap;
 public:
-  ShenandoahFinalTraversalCollectionTask(ShenandoahRootProcessor* rp, ShenandoahTaskTerminator* terminator) :
+  ShenandoahFinalTraversalCollectionTask(ShenandoahRootScanner* rp, ShenandoahTaskTerminator* terminator) :
     AbstractGangTask("Shenandoah Final Traversal Collection"),
     _rp(rp),
     _terminator(terminator),
@@ -273,23 +274,23 @@
     // roots here.
     if (!_heap->is_degenerated_gc_in_progress()) {
       ShenandoahTraversalClosure roots_cl(q, rp);
-      CLDToOopClosure cld_cl(&roots_cl, ClassLoaderData::_claim_strong);
       ShenandoahTraversalSATBThreadsClosure tc(&satb_cl);
       if (unload_classes) {
         ShenandoahRemarkCLDClosure remark_cld_cl(&roots_cl);
-        _rp->process_strong_roots(&roots_cl, &remark_cld_cl, NULL, &tc, worker_id);
+        _rp->strong_roots_do(worker_id, &roots_cl, &remark_cld_cl, NULL, &tc);
       } else {
-        _rp->process_all_roots(&roots_cl, &cld_cl, NULL, &tc, worker_id);
+        CLDToOopClosure cld_cl(&roots_cl, ClassLoaderData::_claim_strong);
+        _rp->roots_do(worker_id, &roots_cl, &cld_cl, NULL, &tc);
       }
     } else {
       ShenandoahTraversalDegenClosure roots_cl(q, rp);
-      CLDToOopClosure cld_cl(&roots_cl, ClassLoaderData::_claim_strong);
       ShenandoahTraversalSATBThreadsClosure tc(&satb_cl);
       if (unload_classes) {
         ShenandoahRemarkCLDClosure remark_cld_cl(&roots_cl);
-        _rp->process_strong_roots(&roots_cl, &remark_cld_cl, NULL, &tc, worker_id);
+        _rp->strong_roots_do(worker_id, &roots_cl, &remark_cld_cl, NULL, &tc);
       } else {
-        _rp->process_all_roots(&roots_cl, &cld_cl, NULL, &tc, worker_id);
+        CLDToOopClosure cld_cl(&roots_cl, ClassLoaderData::_claim_strong);
+        _rp->roots_do(worker_id, &roots_cl, &cld_cl, NULL, &tc);
       }
     }
 
@@ -309,6 +310,9 @@
   _task_queues(new ShenandoahObjToScanQueueSet(heap->max_workers())),
   _traversal_set(ShenandoahHeapRegionSet()) {
 
+  // Traversal does not support concurrent code root scanning
+  FLAG_SET_DEFAULT(ShenandoahConcurrentScanCodeRoots, false);
+
   uint num_queues = heap->max_workers();
   for (uint i = 0; i < num_queues; ++i) {
     ShenandoahObjToScanQueue* task_queue = new ShenandoahObjToScanQueue();
@@ -411,7 +415,7 @@
     {
       uint nworkers = _heap->workers()->active_workers();
       task_queues()->reserve(nworkers);
-      ShenandoahRootProcessor rp(_heap, nworkers, ShenandoahPhaseTimings::init_traversal_gc_work);
+      ShenandoahRootScanner rp(nworkers, ShenandoahPhaseTimings::init_traversal_gc_work);
 
       ShenandoahCsetCodeRootsIterator cset_coderoots = ShenandoahCodeRoots::cset_iterator();
 
@@ -584,7 +588,7 @@
     task_queues()->reserve(nworkers);
 
     // Finish traversal
-    ShenandoahRootProcessor rp(_heap, nworkers, ShenandoahPhaseTimings::final_traversal_gc_work);
+    ShenandoahRootScanner rp(nworkers, ShenandoahPhaseTimings::final_traversal_gc_work);
     ShenandoahTerminationTracker term(ShenandoahPhaseTimings::final_traversal_gc_termination);
 
     ShenandoahTaskTerminator terminator(nworkers, task_queues());
@@ -693,10 +697,10 @@
 
 class ShenandoahTraversalFixRootsTask : public AbstractGangTask {
 private:
-  ShenandoahRootProcessor* _rp;
+  ShenandoahRootUpdater* _rp;
 
 public:
-  ShenandoahTraversalFixRootsTask(ShenandoahRootProcessor* rp) :
+  ShenandoahTraversalFixRootsTask(ShenandoahRootUpdater* rp) :
     AbstractGangTask("Shenandoah traversal fix roots"),
     _rp(rp) {
     assert(ShenandoahHeap::heap()->has_forwarded_objects(), "Must be");
@@ -705,9 +709,8 @@
   void work(uint worker_id) {
     ShenandoahParallelWorkerSession worker_session(worker_id);
     ShenandoahTraversalFixRootsClosure cl;
-    MarkingCodeBlobClosure blobsCl(&cl, CodeBlobToOopClosure::FixRelocations);
-    CLDToOopClosure cldCl(&cl, ClassLoaderData::_claim_strong);
-    _rp->update_all_roots<ShenandoahForwardedIsAliveClosure>(&cl, &cldCl, &blobsCl, NULL, worker_id);
+    ShenandoahForwardedIsAliveClosure is_alive;
+    _rp->roots_do<ShenandoahForwardedIsAliveClosure, ShenandoahTraversalFixRootsClosure>(worker_id, &is_alive, &cl);
   }
 };
 
@@ -715,7 +718,7 @@
 #if defined(COMPILER2) || INCLUDE_JVMCI
   DerivedPointerTable::clear();
 #endif
-  ShenandoahRootProcessor rp(_heap, _heap->workers()->active_workers(), ShenandoahPhaseTimings::final_traversal_update_roots);
+  ShenandoahRootUpdater rp(_heap->workers()->active_workers(), ShenandoahPhaseTimings::final_traversal_update_roots, true /* update code cache */);
   ShenandoahTraversalFixRootsTask update_roots_task(&rp);
   _heap->workers()->run_task(&update_roots_task);
 #if defined(COMPILER2) || INCLUDE_JVMCI