--- a/hotspot/src/share/vm/gc/g1/g1CollectedHeap.cpp	Wed Jun 28 10:58:19 2017 +0200
+++ b/hotspot/src/share/vm/gc/g1/g1CollectedHeap.cpp	Wed Jun 28 12:11:48 2017 +0200
@@ -2397,12 +2397,10 @@
   _hrm.iterate(cl);
 }
 
-void
-G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
-                                         uint worker_id,
-                                         HeapRegionClaimer *hrclaimer,
-                                         bool concurrent) const {
-  _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
+void G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
+                                              uint worker_id,
+                                              HeapRegionClaimer *hrclaimer) const {
+  _hrm.par_iterate(cl, worker_id, hrclaimer);
 }
 
 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {

--- a/hotspot/src/share/vm/gc/g1/g1CollectedHeap.hpp	Wed Jun 28 10:58:19 2017 +0200
+++ b/hotspot/src/share/vm/gc/g1/g1CollectedHeap.hpp	Wed Jun 28 12:11:48 2017 +0200
@@ -1195,17 +1195,14 @@
   inline HeapWord* bottom_addr_for_region(uint index) const;
 
   // Iterate over the heap regions in parallel. Assumes that this will be called
-  // in parallel by ParallelGCThreads worker threads with distinct worker ids
-  // in the range [0..max(ParallelGCThreads-1, 1)]. Applies "blk->doHeapRegion"
+  // in parallel by a number of worker threads with distinct worker ids
+  // in the range passed to the HeapRegionClaimer. Applies "blk->doHeapRegion"
   // to each of the regions, by attempting to claim the region using the
   // HeapRegionClaimer and, if successful, applying the closure to the claimed
-  // region. The concurrent argument should be set to true if iteration is
-  // performed concurrently, during which no assumptions are made for consistent
-  // attributes of the heap regions (as they might be modified while iterating).
+  // region.
   void heap_region_par_iterate(HeapRegionClosure* cl,
                                uint worker_id,
-                               HeapRegionClaimer* hrclaimer,
-                               bool concurrent = false) const;
+                               HeapRegionClaimer* hrclaimer) const;
 
   // Iterate over the regions (if any) in the current collection set.
   void collection_set_iterate(HeapRegionClosure* blk);

--- a/hotspot/src/share/vm/gc/g1/g1ConcurrentMark.cpp	Wed Jun 28 10:58:19 2017 +0200
+++ b/hotspot/src/share/vm/gc/g1/g1ConcurrentMark.cpp	Wed Jun 28 12:11:48 2017 +0200
@@ -703,7 +703,7 @@
 
   void work(uint worker_id) {
     SuspendibleThreadSetJoiner sts_join(_suspendible);
-    G1CollectedHeap::heap()->heap_region_par_iterate(&_cl, worker_id, &_hr_claimer, true);
+    G1CollectedHeap::heap()->heap_region_par_iterate(&_cl, worker_id, &_hr_claimer);
   }
 
   bool is_complete() {

--- a/hotspot/src/share/vm/gc/g1/heapRegionManager.cpp	Wed Jun 28 10:58:19 2017 +0200
+++ b/hotspot/src/share/vm/gc/g1/heapRegionManager.cpp	Wed Jun 28 12:11:48 2017 +0200
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2016, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2017, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -327,7 +327,7 @@
   return true;
 }
 
-void HeapRegionManager::par_iterate(HeapRegionClosure* blk, uint worker_id, HeapRegionClaimer* hrclaimer, bool concurrent) const {
+void HeapRegionManager::par_iterate(HeapRegionClosure* blk, uint worker_id, HeapRegionClaimer* hrclaimer) const {
   const uint start_index = hrclaimer->start_region_for_worker(worker_id);
 
   // Every worker will actually look at all regions, skipping over regions that

--- a/hotspot/src/share/vm/gc/g1/heapRegionManager.hpp	Wed Jun 28 10:58:19 2017 +0200
+++ b/hotspot/src/share/vm/gc/g1/heapRegionManager.hpp	Wed Jun 28 12:11:48 2017 +0200
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2016, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2017, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -240,7 +240,7 @@
   // terminating the iteration early if doHeapRegion() returns true.
   void iterate(HeapRegionClosure* blk) const;
 
-  void par_iterate(HeapRegionClosure* blk, uint worker_id, HeapRegionClaimer* hrclaimer, bool concurrent) const;
+  void par_iterate(HeapRegionClosure* blk, uint worker_id, HeapRegionClaimer* hrclaimer) const;
 
   // Uncommit up to num_regions_to_remove regions that are completely free.
   // Return the actual number of uncommitted regions.