changeset 2216:1216415d8e35

7014923: G1: code cleanup Summary: Some G1 code cleanup. Reviewed-by: johnc, jcoomes, jwilhelm
author tonyp
date Fri, 04 Mar 2011 17:13:19 -0500
parents 11303bede852
children a2c2eac1ca62
files src/share/vm/gc_implementation/g1/concurrentMark.cpp src/share/vm/gc_implementation/g1/concurrentMarkThread.cpp src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp src/share/vm/gc_implementation/g1/g1MarkSweep.cpp src/share/vm/gc_implementation/g1/g1RemSet.cpp src/share/vm/gc_implementation/g1/heapRegion.hpp src/share/vm/gc_implementation/g1/heapRegionSeq.cpp src/share/vm/gc_implementation/g1/heapRegionSeq.hpp src/share/vm/gc_implementation/g1/heapRegionSet.cpp src/share/vm/gc_implementation/g1/heapRegionSet.hpp src/share/vm/gc_implementation/g1/heapRegionSet.inline.hpp src/share/vm/gc_implementation/g1/heapRegionSets.cpp src/share/vm/utilities/debug.hpp src/share/vm/utilities/globalDefinitions.hpp
diffstat 15 files changed, 310 insertions(+), 318 deletions(-) [+]
line wrap: on
line diff
--- a/src/share/vm/gc_implementation/g1/concurrentMark.cpp	Thu Mar 03 21:02:56 2011 -0800
+++ b/src/share/vm/gc_implementation/g1/concurrentMark.cpp	Fri Mar 04 17:13:19 2011 -0500
@@ -1828,7 +1828,7 @@
   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 
   _cleanup_list.verify_optional();
-  FreeRegionList local_free_list("Local Cleanup List");
+  FreeRegionList tmp_free_list("Tmp Free List");
 
   if (G1ConcRegionFreeingVerbose) {
     gclog_or_tty->print_cr("G1ConcRegionFreeing [complete cleanup] : "
@@ -1842,7 +1842,7 @@
     HeapRegion* hr = _cleanup_list.remove_head();
     assert(hr != NULL, "the list was not empty");
     hr->rem_set()->clear();
-    local_free_list.add_as_tail(hr);
+    tmp_free_list.add_as_tail(hr);
 
     // Instead of adding one region at a time to the secondary_free_list,
     // we accumulate them in the local list and move them a few at a
@@ -1850,20 +1850,20 @@
     // we do during this process. We'll also append the local list when
     // _cleanup_list is empty (which means we just removed the last
     // region from the _cleanup_list).
-    if ((local_free_list.length() % G1SecondaryFreeListAppendLength == 0) ||
+    if ((tmp_free_list.length() % G1SecondaryFreeListAppendLength == 0) ||
         _cleanup_list.is_empty()) {
       if (G1ConcRegionFreeingVerbose) {
         gclog_or_tty->print_cr("G1ConcRegionFreeing [complete cleanup] : "
                                "appending "SIZE_FORMAT" entries to the "
                                "secondary_free_list, clean list still has "
                                SIZE_FORMAT" entries",
-                               local_free_list.length(),
+                               tmp_free_list.length(),
                                _cleanup_list.length());
       }
 
       {
         MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
-        g1h->secondary_free_list_add_as_tail(&local_free_list);
+        g1h->secondary_free_list_add_as_tail(&tmp_free_list);
         SecondaryFreeList_lock->notify_all();
       }
 
@@ -1874,7 +1874,7 @@
       }
     }
   }
-  assert(local_free_list.is_empty(), "post-condition");
+  assert(tmp_free_list.is_empty(), "post-condition");
 }
 
 // Support closures for reference procssing in G1
@@ -3182,7 +3182,7 @@
 
   template <class T> void do_oop_work(T* p) {
     assert( _g1h->is_in_g1_reserved((HeapWord*) p), "invariant");
-    assert(!_g1h->is_on_free_list(
+    assert(!_g1h->is_on_master_free_list(
                     _g1h->heap_region_containing((HeapWord*) p)), "invariant");
 
     oop obj = oopDesc::load_decode_heap_oop(p);
@@ -3403,7 +3403,7 @@
 void CMTask::push(oop obj) {
   HeapWord* objAddr = (HeapWord*) obj;
   assert(_g1h->is_in_g1_reserved(objAddr), "invariant");
-  assert(!_g1h->is_on_free_list(
+  assert(!_g1h->is_on_master_free_list(
               _g1h->heap_region_containing((HeapWord*) objAddr)), "invariant");
   assert(!_g1h->is_obj_ill(obj), "invariant");
   assert(_nextMarkBitMap->isMarked(objAddr), "invariant");
@@ -3649,7 +3649,7 @@
                                (void*) obj);
 
       assert(_g1h->is_in_g1_reserved((HeapWord*) obj), "invariant" );
-      assert(!_g1h->is_on_free_list(
+      assert(!_g1h->is_on_master_free_list(
                   _g1h->heap_region_containing((HeapWord*) obj)), "invariant");
 
       scan_object(obj);
--- a/src/share/vm/gc_implementation/g1/concurrentMarkThread.cpp	Thu Mar 03 21:02:56 2011 -0800
+++ b/src/share/vm/gc_implementation/g1/concurrentMarkThread.cpp	Fri Mar 04 17:13:19 2011 -0500
@@ -237,9 +237,9 @@
         // The following will finish freeing up any regions that we
         // found to be empty during cleanup. We'll do this part
         // without joining the suspendible set. If an evacuation pause
-        // takes places, then we would carry on freeing regions in
+        // takes place, then we would carry on freeing regions in
         // case they are needed by the pause. If a Full GC takes
-        // places, it would wait for us to process the regions
+        // place, it would wait for us to process the regions
         // reclaimed by cleanup.
 
         double cleanup_start_sec = os::elapsedTime();
--- a/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp	Thu Mar 03 21:02:56 2011 -0800
+++ b/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp	Fri Mar 04 17:13:19 2011 -0500
@@ -479,7 +479,7 @@
 // Private methods.
 
 HeapRegion*
-G1CollectedHeap::new_region_try_secondary_free_list(size_t word_size) {
+G1CollectedHeap::new_region_try_secondary_free_list() {
   MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
   while (!_secondary_free_list.is_empty() || free_regions_coming()) {
     if (!_secondary_free_list.is_empty()) {
@@ -531,7 +531,7 @@
         gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
                                "forced to look at the secondary_free_list");
       }
-      res = new_region_try_secondary_free_list(word_size);
+      res = new_region_try_secondary_free_list();
       if (res != NULL) {
         return res;
       }
@@ -543,7 +543,7 @@
       gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
                              "res == NULL, trying the secondary_free_list");
     }
-    res = new_region_try_secondary_free_list(word_size);
+    res = new_region_try_secondary_free_list();
   }
   if (res == NULL && do_expand) {
     if (expand(word_size * HeapWordSize)) {
@@ -579,6 +579,9 @@
 
 int G1CollectedHeap::humongous_obj_allocate_find_first(size_t num_regions,
                                                        size_t word_size) {
+  assert(isHumongous(word_size), "word_size should be humongous");
+  assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
+
   int first = -1;
   if (num_regions == 1) {
     // Only one region to allocate, no need to go through the slower
@@ -600,7 +603,7 @@
     // request. If we are only allocating one region we use the common
     // region allocation code (see above).
     wait_while_free_regions_coming();
-    append_secondary_free_list_if_not_empty();
+    append_secondary_free_list_if_not_empty_with_lock();
 
     if (free_regions() >= num_regions) {
       first = _hrs->find_contiguous(num_regions);
@@ -608,7 +611,7 @@
         for (int i = first; i < first + (int) num_regions; ++i) {
           HeapRegion* hr = _hrs->at(i);
           assert(hr->is_empty(), "sanity");
-          assert(is_on_free_list(hr), "sanity");
+          assert(is_on_master_free_list(hr), "sanity");
           hr->set_pending_removal(true);
         }
         _free_list.remove_all_pending(num_regions);
@@ -618,6 +621,126 @@
   return first;
 }
 
+HeapWord*
+G1CollectedHeap::humongous_obj_allocate_initialize_regions(int first,
+                                                           size_t num_regions,
+                                                           size_t word_size) {
+  assert(first != -1, "pre-condition");
+  assert(isHumongous(word_size), "word_size should be humongous");
+  assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
+
+  // Index of last region in the series + 1.
+  int last = first + (int) num_regions;
+
+  // We need to initialize the region(s) we just discovered. This is
+  // a bit tricky given that it can happen concurrently with
+  // refinement threads refining cards on these regions and
+  // potentially wanting to refine the BOT as they are scanning
+  // those cards (this can happen shortly after a cleanup; see CR
+  // 6991377). So we have to set up the region(s) carefully and in
+  // a specific order.
+
+  // The word size sum of all the regions we will allocate.
+  size_t word_size_sum = num_regions * HeapRegion::GrainWords;
+  assert(word_size <= word_size_sum, "sanity");
+
+  // This will be the "starts humongous" region.
+  HeapRegion* first_hr = _hrs->at(first);
+  // The header of the new object will be placed at the bottom of
+  // the first region.
+  HeapWord* new_obj = first_hr->bottom();
+  // This will be the new end of the first region in the series that
+  // should also match the end of the last region in the seriers.
+  HeapWord* new_end = new_obj + word_size_sum;
+  // This will be the new top of the first region that will reflect
+  // this allocation.
+  HeapWord* new_top = new_obj + word_size;
+
+  // First, we need to zero the header of the space that we will be
+  // allocating. When we update top further down, some refinement
+  // threads might try to scan the region. By zeroing the header we
+  // ensure that any thread that will try to scan the region will
+  // come across the zero klass word and bail out.
+  //
+  // NOTE: It would not have been correct to have used
+  // CollectedHeap::fill_with_object() and make the space look like
+  // an int array. The thread that is doing the allocation will
+  // later update the object header to a potentially different array
+  // type and, for a very short period of time, the klass and length
+  // fields will be inconsistent. This could cause a refinement
+  // thread to calculate the object size incorrectly.
+  Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
+
+  // We will set up the first region as "starts humongous". This
+  // will also update the BOT covering all the regions to reflect
+  // that there is a single object that starts at the bottom of the
+  // first region.
+  first_hr->set_startsHumongous(new_top, new_end);
+
+  // Then, if there are any, we will set up the "continues
+  // humongous" regions.
+  HeapRegion* hr = NULL;
+  for (int i = first + 1; i < last; ++i) {
+    hr = _hrs->at(i);
+    hr->set_continuesHumongous(first_hr);
+  }
+  // If we have "continues humongous" regions (hr != NULL), then the
+  // end of the last one should match new_end.
+  assert(hr == NULL || hr->end() == new_end, "sanity");
+
+  // Up to this point no concurrent thread would have been able to
+  // do any scanning on any region in this series. All the top
+  // fields still point to bottom, so the intersection between
+  // [bottom,top] and [card_start,card_end] will be empty. Before we
+  // update the top fields, we'll do a storestore to make sure that
+  // no thread sees the update to top before the zeroing of the
+  // object header and the BOT initialization.
+  OrderAccess::storestore();
+
+  // Now that the BOT and the object header have been initialized,
+  // we can update top of the "starts humongous" region.
+  assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
+         "new_top should be in this region");
+  first_hr->set_top(new_top);
+
+  // Now, we will update the top fields of the "continues humongous"
+  // regions. The reason we need to do this is that, otherwise,
+  // these regions would look empty and this will confuse parts of
+  // G1. For example, the code that looks for a consecutive number
+  // of empty regions will consider them empty and try to
+  // re-allocate them. We can extend is_empty() to also include
+  // !continuesHumongous(), but it is easier to just update the top
+  // fields here. The way we set top for all regions (i.e., top ==
+  // end for all regions but the last one, top == new_top for the
+  // last one) is actually used when we will free up the humongous
+  // region in free_humongous_region().
+  hr = NULL;
+  for (int i = first + 1; i < last; ++i) {
+    hr = _hrs->at(i);
+    if ((i + 1) == last) {
+      // last continues humongous region
+      assert(hr->bottom() < new_top && new_top <= hr->end(),
+             "new_top should fall on this region");
+      hr->set_top(new_top);
+    } else {
+      // not last one
+      assert(new_top > hr->end(), "new_top should be above this region");
+      hr->set_top(hr->end());
+    }
+  }
+  // If we have continues humongous regions (hr != NULL), then the
+  // end of the last one should match new_end and its top should
+  // match new_top.
+  assert(hr == NULL ||
+         (hr->end() == new_end && hr->top() == new_top), "sanity");
+
+  assert(first_hr->used() == word_size * HeapWordSize, "invariant");
+  _summary_bytes_used += first_hr->used();
+  _humongous_set.add(first_hr);
+
+  return new_obj;
+}
+
 // If could fit into free regions w/o expansion, try.
 // Otherwise, if can expand, do so.
 // Otherwise, if using ex regions might help, try with ex given back.
@@ -653,121 +776,16 @@
     }
   }
 
+  HeapWord* result = NULL;
   if (first != -1) {
-    // Index of last region in the series + 1.
-    int last = first + (int) num_regions;
-
-    // We need to initialize the region(s) we just discovered. This is
-    // a bit tricky given that it can happen concurrently with
-    // refinement threads refining cards on these regions and
-    // potentially wanting to refine the BOT as they are scanning
-    // those cards (this can happen shortly after a cleanup; see CR
-    // 6991377). So we have to set up the region(s) carefully and in
-    // a specific order.
-
-    // The word size sum of all the regions we will allocate.
-    size_t word_size_sum = num_regions * HeapRegion::GrainWords;
-    assert(word_size <= word_size_sum, "sanity");
-
-    // This will be the "starts humongous" region.
-    HeapRegion* first_hr = _hrs->at(first);
-    // The header of the new object will be placed at the bottom of
-    // the first region.
-    HeapWord* new_obj = first_hr->bottom();
-    // This will be the new end of the first region in the series that
-    // should also match the end of the last region in the seriers.
-    HeapWord* new_end = new_obj + word_size_sum;
-    // This will be the new top of the first region that will reflect
-    // this allocation.
-    HeapWord* new_top = new_obj + word_size;
-
-    // First, we need to zero the header of the space that we will be
-    // allocating. When we update top further down, some refinement
-    // threads might try to scan the region. By zeroing the header we
-    // ensure that any thread that will try to scan the region will
-    // come across the zero klass word and bail out.
-    //
-    // NOTE: It would not have been correct to have used
-    // CollectedHeap::fill_with_object() and make the space look like
-    // an int array. The thread that is doing the allocation will
-    // later update the object header to a potentially different array
-    // type and, for a very short period of time, the klass and length
-    // fields will be inconsistent. This could cause a refinement
-    // thread to calculate the object size incorrectly.
-    Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
-
-    // We will set up the first region as "starts humongous". This
-    // will also update the BOT covering all the regions to reflect
-    // that there is a single object that starts at the bottom of the
-    // first region.
-    first_hr->set_startsHumongous(new_top, new_end);
-
-    // Then, if there are any, we will set up the "continues
-    // humongous" regions.
-    HeapRegion* hr = NULL;
-    for (int i = first + 1; i < last; ++i) {
-      hr = _hrs->at(i);
-      hr->set_continuesHumongous(first_hr);
-    }
-    // If we have "continues humongous" regions (hr != NULL), then the
-    // end of the last one should match new_end.
-    assert(hr == NULL || hr->end() == new_end, "sanity");
-
-    // Up to this point no concurrent thread would have been able to
-    // do any scanning on any region in this series. All the top
-    // fields still point to bottom, so the intersection between
-    // [bottom,top] and [card_start,card_end] will be empty. Before we
-    // update the top fields, we'll do a storestore to make sure that
-    // no thread sees the update to top before the zeroing of the
-    // object header and the BOT initialization.
-    OrderAccess::storestore();
-
-    // Now that the BOT and the object header have been initialized,
-    // we can update top of the "starts humongous" region.
-    assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
-           "new_top should be in this region");
-    first_hr->set_top(new_top);
-
-    // Now, we will update the top fields of the "continues humongous"
-    // regions. The reason we need to do this is that, otherwise,
-    // these regions would look empty and this will confuse parts of
-    // G1. For example, the code that looks for a consecutive number
-    // of empty regions will consider them empty and try to
-    // re-allocate them. We can extend is_empty() to also include
-    // !continuesHumongous(), but it is easier to just update the top
-    // fields here. The way we set top for all regions (i.e., top ==
-    // end for all regions but the last one, top == new_top for the
-    // last one) is actually used when we will free up the humongous
-    // region in free_humongous_region().
-    hr = NULL;
-    for (int i = first + 1; i < last; ++i) {
-      hr = _hrs->at(i);
-      if ((i + 1) == last) {
-        // last continues humongous region
-        assert(hr->bottom() < new_top && new_top <= hr->end(),
-               "new_top should fall on this region");
-        hr->set_top(new_top);
-      } else {
-        // not last one
-        assert(new_top > hr->end(), "new_top should be above this region");
-        hr->set_top(hr->end());
-      }
-    }
-    // If we have continues humongous regions (hr != NULL), then the
-    // end of the last one should match new_end and its top should
-    // match new_top.
-    assert(hr == NULL ||
-           (hr->end() == new_end && hr->top() == new_top), "sanity");
-
-    assert(first_hr->used() == word_size * HeapWordSize, "invariant");
-    _summary_bytes_used += first_hr->used();
-    _humongous_set.add(first_hr);
-
-    return new_obj;
+    result =
+      humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
+    assert(result != NULL, "it should always return a valid result");
   }
 
   verify_region_sets_optional();
-  return NULL;
+
+  return result;
 }
 
 void
@@ -1389,7 +1407,7 @@
     g1_policy()->record_full_collection_start();
 
     wait_while_free_regions_coming();
-    append_secondary_free_list_if_not_empty();
+    append_secondary_free_list_if_not_empty_with_lock();
 
     gc_prologue(true);
     increment_total_collections(true /* full gc */);
@@ -3377,15 +3395,14 @@
 
     TraceMemoryManagerStats tms(false /* fullGC */);
 
-    // If there are any free regions available on the secondary_free_list
-    // make sure we append them to the free_list. However, we don't
-    // have to wait for the rest of the cleanup operation to
-    // finish. If it's still going on that's OK. If we run out of
-    // regions, the region allocation code will check the
-    // secondary_free_list and potentially wait if more free regions
-    // are coming (see new_region_try_secondary_free_list()).
+    // If the secondary_free_list is not empty, append it to the
+    // free_list. No need to wait for the cleanup operation to finish;
+    // the region allocation code will check the secondary_free_list
+    // and wait if necessary. If the G1StressConcRegionFreeing flag is
+    // set, skip this step so that the region allocation code has to
+    // get entries from the secondary_free_list.
     if (!G1StressConcRegionFreeing) {
-      append_secondary_free_list_if_not_empty();
+      append_secondary_free_list_if_not_empty_with_lock();
     }
 
     increment_gc_time_stamp();
@@ -5199,7 +5216,7 @@
   size_t rs_lengths = 0;
 
   while (cur != NULL) {
-    assert(!is_on_free_list(cur), "sanity");
+    assert(!is_on_master_free_list(cur), "sanity");
 
     if (non_young) {
       if (cur->is_young()) {
@@ -5543,13 +5560,10 @@
     return;
   }
 
-  {
-    MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
-    // Make sure we append the secondary_free_list on the free_list so
-    // that all free regions we will come across can be safely
-    // attributed to the free_list.
-    append_secondary_free_list();
-  }
+  // Make sure we append the secondary_free_list on the free_list so
+  // that all free regions we will come across can be safely
+  // attributed to the free_list.
+  append_secondary_free_list_if_not_empty_with_lock();
 
   // Finally, make sure that the region accounting in the lists is
   // consistent with what we see in the heap.
--- a/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp	Thu Mar 03 21:02:56 2011 -0800
+++ b/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp	Fri Mar 04 17:13:19 2011 -0500
@@ -56,7 +56,6 @@
 class ConcurrentMark;
 class ConcurrentMarkThread;
 class ConcurrentG1Refine;
-class ConcurrentZFThread;
 
 typedef OverflowTaskQueue<StarTask>         RefToScanQueue;
 typedef GenericTaskQueueSet<RefToScanQueue> RefToScanQueueSet;
@@ -64,12 +63,6 @@
 typedef int RegionIdx_t;   // needs to hold [ 0..max_regions() )
 typedef int CardIdx_t;     // needs to hold [ 0..CardsPerRegion )
 
-enum G1GCThreadGroups {
-  G1CRGroup = 0,
-  G1ZFGroup = 1,
-  G1CMGroup = 2
-};
-
 enum GCAllocPurpose {
   GCAllocForTenured,
   GCAllocForSurvived,
@@ -294,9 +287,9 @@
   // These are macros so that, if the assert fires, we get the correct
   // line number, file, etc.
 
-#define heap_locking_asserts_err_msg(__extra_message)                         \
+#define heap_locking_asserts_err_msg(_extra_message_)                         \
   err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s",    \
-          (__extra_message),                                                  \
+          (_extra_message_),                                                  \
           BOOL_TO_STR(Heap_lock->owned_by_self()),                            \
           BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()),               \
           BOOL_TO_STR(Thread::current()->is_VM_thread()))
@@ -307,11 +300,11 @@
            heap_locking_asserts_err_msg("should be holding the Heap_lock"));  \
   } while (0)
 
-#define assert_heap_locked_or_at_safepoint(__should_be_vm_thread)             \
+#define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_)             \
   do {                                                                        \
     assert(Heap_lock->owned_by_self() ||                                      \
            (SafepointSynchronize::is_at_safepoint() &&                        \
-             ((__should_be_vm_thread) == Thread::current()->is_VM_thread())), \
+             ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
            heap_locking_asserts_err_msg("should be holding the Heap_lock or " \
                                         "should be at a safepoint"));         \
   } while (0)
@@ -338,10 +331,10 @@
                                    "should not be at a safepoint"));          \
   } while (0)
 
-#define assert_at_safepoint(__should_be_vm_thread)                            \
+#define assert_at_safepoint(_should_be_vm_thread_)                            \
   do {                                                                        \
     assert(SafepointSynchronize::is_at_safepoint() &&                         \
-              ((__should_be_vm_thread) == Thread::current()->is_VM_thread()), \
+              ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
            heap_locking_asserts_err_msg("should be at a safepoint"));         \
   } while (0)
 
@@ -371,35 +364,40 @@
   // will check whether there's anything available in the
   // secondary_free_list and/or wait for more regions to appear in that
   // list, if _free_regions_coming is set.
-  HeapRegion* new_region_try_secondary_free_list(size_t word_size);
+  HeapRegion* new_region_try_secondary_free_list();
 
-  // It will try to allocate a single non-humongous HeapRegion
-  // sufficient for an allocation of the given word_size.  If
-  // do_expand is true, it will attempt to expand the heap if
-  // necessary to satisfy the allocation request. Note that word_size
-  // is only used to make sure that we expand sufficiently but, given
-  // that the allocation request is assumed not to be humongous,
-  // having word_size is not strictly necessary (expanding by a single
-  // region will always be sufficient). But let's keep that parameter
-  // in case we need it in the future.
+  // Try to allocate a single non-humongous HeapRegion sufficient for
+  // an allocation of the given word_size. If do_expand is true,
+  // attempt to expand the heap if necessary to satisfy the allocation
+  // request.
   HeapRegion* new_region_work(size_t word_size, bool do_expand);
 
-  // It will try to allocate a new region to be used for allocation by
-  // mutator threads. It will not try to expand the heap if not region
-  // is available.
+  // Try to allocate a new region to be used for allocation by a
+  // mutator thread. Attempt to expand the heap if no region is
+  // available.
   HeapRegion* new_alloc_region(size_t word_size) {
     return new_region_work(word_size, false /* do_expand */);
   }
 
-  // It will try to allocate a new region to be used for allocation by
-  // a GC thread. It will try to expand the heap if no region is
-  // available.
+  // Try to allocate a new region to be used for allocation by a GC
+  // thread. Attempt to expand the heap if no region is available.
   HeapRegion* new_gc_alloc_region(int purpose, size_t word_size);
 
+  // Attempt to satisfy a humongous allocation request of the given
+  // size by finding a contiguous set of free regions of num_regions
+  // length and remove them from the master free list. Return the
+  // index of the first region or -1 if the search was unsuccessful.
   int humongous_obj_allocate_find_first(size_t num_regions, size_t word_size);
 
-  // Attempt to allocate an object of the given (very large) "word_size".
-  // Returns "NULL" on failure.
+  // Initialize a contiguous set of free regions of length num_regions
+  // and starting at index first so that they appear as a single
+  // humongous region.
+  HeapWord* humongous_obj_allocate_initialize_regions(int first,
+                                                      size_t num_regions,
+                                                      size_t word_size);
+
+  // Attempt to allocate a humongous object of the given size. Return
+  // NULL if unsuccessful.
   HeapWord* humongous_obj_allocate(size_t word_size);
 
   // The following two methods, allocate_new_tlab() and
@@ -776,7 +774,7 @@
   // Invoke "save_marks" on all heap regions.
   void save_marks();
 
-  // It frees a non-humongous region by initializing its contents and
+  // Frees a non-humongous region by initializing its contents and
   // adding it to the free list that's passed as a parameter (this is
   // usually a local list which will be appended to the master free
   // list later). The used bytes of freed regions are accumulated in
@@ -787,13 +785,13 @@
                    FreeRegionList* free_list,
                    bool par);
 
-  // It frees a humongous region by collapsing it into individual
-  // regions and calling free_region() for each of them. The freed
-  // regions will be added to the free list that's passed as a parameter
-  // (this is usually a local list which will be appended to the
-  // master free list later). The used bytes of freed regions are
-  // accumulated in pre_used. If par is true, the region's RSet will
-  // not be freed up. The assumption is that this will be done later.
+  // Frees a humongous region by collapsing it into individual regions
+  // and calling free_region() for each of them. The freed regions
+  // will be added to the free list that's passed as a parameter (this
+  // is usually a local list which will be appended to the master free
+  // list later). The used bytes of freed regions are accumulated in
+  // pre_used. If par is true, the region's RSet will not be freed
+  // up. The assumption is that this will be done later.
   void free_humongous_region(HeapRegion* hr,
                              size_t* pre_used,
                              FreeRegionList* free_list,
@@ -1046,13 +1044,13 @@
 #endif // HEAP_REGION_SET_FORCE_VERIFY
 
 #ifdef ASSERT
-  bool is_on_free_list(HeapRegion* hr) {
+  bool is_on_master_free_list(HeapRegion* hr) {
     return hr->containing_set() == &_free_list;
   }
 
-  bool is_on_humongous_set(HeapRegion* hr) {
+  bool is_in_humongous_set(HeapRegion* hr) {
     return hr->containing_set() == &_humongous_set;
-}
+  }
 #endif // ASSERT
 
   // Wrapper for the region list operations that can be called from
@@ -1066,7 +1064,9 @@
     _free_list.add_as_tail(&_secondary_free_list);
   }
 
-  void append_secondary_free_list_if_not_empty() {
+  void append_secondary_free_list_if_not_empty_with_lock() {
+    // If the secondary free list looks empty there's no reason to
+    // take the lock and then try to append it.
     if (!_secondary_free_list.is_empty()) {
       MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
       append_secondary_free_list();
--- a/src/share/vm/gc_implementation/g1/g1MarkSweep.cpp	Thu Mar 03 21:02:56 2011 -0800
+++ b/src/share/vm/gc_implementation/g1/g1MarkSweep.cpp	Fri Mar 04 17:13:19 2011 -0500
@@ -185,22 +185,22 @@
   G1CollectedHeap* _g1h;
   ModRefBarrierSet* _mrbs;
   CompactPoint _cp;
-  size_t _pre_used;
-  FreeRegionList _free_list;
   HumongousRegionSet _humongous_proxy_set;
 
   void free_humongous_region(HeapRegion* hr) {
     HeapWord* end = hr->end();
+    size_t dummy_pre_used;
+    FreeRegionList dummy_free_list("Dummy Free List for G1MarkSweep");
+
     assert(hr->startsHumongous(),
            "Only the start of a humongous region should be freed.");
-    _g1h->free_humongous_region(hr, &_pre_used, &_free_list,
+    _g1h->free_humongous_region(hr, &dummy_pre_used, &dummy_free_list,
                                 &_humongous_proxy_set, false /* par */);
-    // Do we also need to do this for the continues humongous regions
-    // we just collapsed?
     hr->prepare_for_compaction(&_cp);
     // Also clear the part of the card table that will be unused after
     // compaction.
     _mrbs->clear(MemRegion(hr->compaction_top(), end));
+    dummy_free_list.remove_all();
   }
 
 public:
@@ -208,8 +208,6 @@
   : _g1h(G1CollectedHeap::heap()),
     _mrbs(G1CollectedHeap::heap()->mr_bs()),
     _cp(NULL, cs, cs->initialize_threshold()),
-    _pre_used(0),
-    _free_list("Local Free List for G1MarkSweep"),
     _humongous_proxy_set("G1MarkSweep Humongous Proxy Set") { }
 
   void update_sets() {
@@ -219,7 +217,6 @@
                                             NULL, /* free_list */
                                             &_humongous_proxy_set,
                                             false /* par */);
-    _free_list.remove_all();
   }
 
   bool doHeapRegion(HeapRegion* hr) {
--- a/src/share/vm/gc_implementation/g1/g1RemSet.cpp	Thu Mar 03 21:02:56 2011 -0800
+++ b/src/share/vm/gc_implementation/g1/g1RemSet.cpp	Fri Mar 04 17:13:19 2011 -0500
@@ -86,28 +86,6 @@
   bool idempotent() { return true; }
 };
 
-class IntoCSRegionClosure: public HeapRegionClosure {
-  IntoCSOopClosure _blk;
-  G1CollectedHeap* _g1;
-public:
-  IntoCSRegionClosure(G1CollectedHeap* g1, OopsInHeapRegionClosure* blk) :
-    _g1(g1), _blk(g1, blk) {}
-  bool doHeapRegion(HeapRegion* r) {
-    if (!r->in_collection_set()) {
-      _blk.set_region(r);
-      if (r->isHumongous()) {
-        if (r->startsHumongous()) {
-          oop obj = oop(r->bottom());
-          obj->oop_iterate(&_blk);
-        }
-      } else {
-        r->oop_before_save_marks_iterate(&_blk);
-      }
-    }
-    return false;
-  }
-};
-
 class VerifyRSCleanCardOopClosure: public OopClosure {
   G1CollectedHeap* _g1;
 public:
--- a/src/share/vm/gc_implementation/g1/heapRegion.hpp	Thu Mar 03 21:02:56 2011 -0800
+++ b/src/share/vm/gc_implementation/g1/heapRegion.hpp	Fri Mar 04 17:13:19 2011 -0500
@@ -53,8 +53,8 @@
 class HeapRegionSetBase;
 
 #define HR_FORMAT "%d:["PTR_FORMAT","PTR_FORMAT","PTR_FORMAT"]"
-#define HR_FORMAT_PARAMS(__hr) (__hr)->hrs_index(), (__hr)->bottom(), \
-                               (__hr)->top(), (__hr)->end()
+#define HR_FORMAT_PARAMS(_hr_) (_hr_)->hrs_index(), (_hr_)->bottom(), \
+                               (_hr_)->top(), (_hr_)->end()
 
 // A dirty card to oop closure for heap regions. It
 // knows how to get the G1 heap and how to use the bitmap
@@ -518,13 +518,13 @@
                    containing_set, _containing_set));
 
     _containing_set = containing_set;
-}
+  }
 
   HeapRegionSetBase* containing_set() { return _containing_set; }
 #else // ASSERT
   void set_containing_set(HeapRegionSetBase* containing_set) { }
 
-  // containing_set() is only used in asserts so there's not reason
+  // containing_set() is only used in asserts so there's no reason
   // to provide a dummy version of it.
 #endif // ASSERT
 
@@ -535,14 +535,15 @@
   bool pending_removal() { return _pending_removal; }
 
   void set_pending_removal(bool pending_removal) {
-    // We can only set pending_removal to true, if it's false and the
-    // region belongs to a set.
-    assert(!pending_removal ||
-           (!_pending_removal && containing_set() != NULL), "pre-condition");
-    // We can only set pending_removal to false, if it's true and the
-    // region does not belong to a set.
-    assert( pending_removal ||
-           ( _pending_removal && containing_set() == NULL), "pre-condition");
+    if (pending_removal) {
+      assert(!_pending_removal && containing_set() != NULL,
+             "can only set pending removal to true if it's false and "
+             "the region belongs to a region set");
+    } else {
+      assert( _pending_removal && containing_set() == NULL,
+              "can only set pending removal to false if it's true and "
+              "the region does not belong to a region set");
+    }
 
     _pending_removal = pending_removal;
   }
--- a/src/share/vm/gc_implementation/g1/heapRegionSeq.cpp	Thu Mar 03 21:02:56 2011 -0800
+++ b/src/share/vm/gc_implementation/g1/heapRegionSeq.cpp	Fri Mar 04 17:13:19 2011 -0500
@@ -165,7 +165,7 @@
 
   assert(num_so_far <= num, "post-condition");
   if (num_so_far == num) {
-    // we find enough space for the humongous object
+    // we found enough space for the humongous object
     assert(from <= first && first < _regions.length(), "post-condition");
     assert(first < curr && (curr - first) == (int) num, "post-condition");
     for (int i = first; i < first + (int) num; ++i) {
--- a/src/share/vm/gc_implementation/g1/heapRegionSeq.hpp	Thu Mar 03 21:02:56 2011 -0800
+++ b/src/share/vm/gc_implementation/g1/heapRegionSeq.hpp	Fri Mar 04 17:13:19 2011 -0500
@@ -76,7 +76,8 @@
   // that are available for allocation.
   size_t free_suffix();
 
-  // Finds a contiguous set of empty regions of length num.
+  // Find a contiguous set of empty regions of length num and return
+  // the index of the first region or -1 if the search was unsuccessful.
   int find_contiguous(size_t num);
 
   // Apply the "doHeapRegion" method of "blk" to all regions in "this",
--- a/src/share/vm/gc_implementation/g1/heapRegionSet.cpp	Thu Mar 03 21:02:56 2011 -0800
+++ b/src/share/vm/gc_implementation/g1/heapRegionSet.cpp	Fri Mar 04 17:13:19 2011 -0500
@@ -42,7 +42,7 @@
   return region_num;
 }
 
-void HeapRegionSetBase::fill_in_ext_msg(hrl_ext_msg* msg, const char* message) {
+void HeapRegionSetBase::fill_in_ext_msg(hrs_ext_msg* msg, const char* message) {
   msg->append("[%s] %s "
               "ln: "SIZE_FORMAT" rn: "SIZE_FORMAT" "
               "cy: "SIZE_FORMAT" ud: "SIZE_FORMAT,
@@ -109,30 +109,30 @@
   // for the verification calls. If we do verification without the
   // appropriate locks and the set changes underneath our feet
   // verification might fail and send us on a wild goose chase.
-  hrl_assert_mt_safety_ok(this);
+  hrs_assert_mt_safety_ok(this);
 
   guarantee(( is_empty() && length() == 0 && region_num() == 0 &&
               total_used_bytes() == 0 && total_capacity_bytes() == 0) ||
             (!is_empty() && length() >= 0 && region_num() >= 0 &&
               total_used_bytes() >= 0 && total_capacity_bytes() >= 0),
-            hrl_ext_msg(this, "invariant"));
+            hrs_ext_msg(this, "invariant"));
 
   guarantee((!regions_humongous() && region_num() == length()) ||
             ( regions_humongous() && region_num() >= length()),
-            hrl_ext_msg(this, "invariant"));
+            hrs_ext_msg(this, "invariant"));
 
   guarantee(!regions_empty() || total_used_bytes() == 0,
-            hrl_ext_msg(this, "invariant"));
+            hrs_ext_msg(this, "invariant"));
 
   guarantee(total_used_bytes() <= total_capacity_bytes(),
-            hrl_ext_msg(this, "invariant"));
+            hrs_ext_msg(this, "invariant"));
 }
 
 void HeapRegionSetBase::verify_start() {
   // See comment in verify() about MT safety and verification.
-  hrl_assert_mt_safety_ok(this);
+  hrs_assert_mt_safety_ok(this);
   assert(!_verify_in_progress,
-         hrl_ext_msg(this, "verification should not be in progress"));
+         hrs_ext_msg(this, "verification should not be in progress"));
 
   // Do the basic verification first before we do the checks over the regions.
   HeapRegionSetBase::verify();
@@ -146,11 +146,11 @@
 
 void HeapRegionSetBase::verify_next_region(HeapRegion* hr) {
   // See comment in verify() about MT safety and verification.
-  hrl_assert_mt_safety_ok(this);
+  hrs_assert_mt_safety_ok(this);
   assert(_verify_in_progress,
-         hrl_ext_msg(this, "verification should be in progress"));
+         hrs_ext_msg(this, "verification should be in progress"));
 
-  guarantee(verify_region(hr, this), hrl_ext_msg(this, "region verification"));
+  guarantee(verify_region(hr, this), hrs_ext_msg(this, "region verification"));
 
   _calc_length               += 1;
   if (!hr->isHumongous()) {
@@ -164,28 +164,28 @@
 
 void HeapRegionSetBase::verify_end() {
   // See comment in verify() about MT safety and verification.
-  hrl_assert_mt_safety_ok(this);
+  hrs_assert_mt_safety_ok(this);
   assert(_verify_in_progress,
-         hrl_ext_msg(this, "verification should be in progress"));
+         hrs_ext_msg(this, "verification should be in progress"));
 
   guarantee(length() == _calc_length,
-            hrl_err_msg("[%s] length: "SIZE_FORMAT" should be == "
+            hrs_err_msg("[%s] length: "SIZE_FORMAT" should be == "
                         "calc length: "SIZE_FORMAT,
                         name(), length(), _calc_length));
 
   guarantee(region_num() == _calc_region_num,
-            hrl_err_msg("[%s] region num: "SIZE_FORMAT" should be == "
+            hrs_err_msg("[%s] region num: "SIZE_FORMAT" should be == "
                         "calc region num: "SIZE_FORMAT,
                         name(), region_num(), _calc_region_num));
 
   guarantee(total_capacity_bytes() == _calc_total_capacity_bytes,
-            hrl_err_msg("[%s] capacity bytes: "SIZE_FORMAT" should be == "
+            hrs_err_msg("[%s] capacity bytes: "SIZE_FORMAT" should be == "
                         "calc capacity bytes: "SIZE_FORMAT,
                         name(),
                         total_capacity_bytes(), _calc_total_capacity_bytes));
 
   guarantee(total_used_bytes() == _calc_total_used_bytes,
-            hrl_err_msg("[%s] used bytes: "SIZE_FORMAT" should be == "
+            hrs_err_msg("[%s] used bytes: "SIZE_FORMAT" should be == "
                         "calc used bytes: "SIZE_FORMAT,
                         name(), total_used_bytes(), _calc_total_used_bytes));
 
@@ -221,9 +221,9 @@
 //////////////////// HeapRegionSet ////////////////////
 
 void HeapRegionSet::update_from_proxy(HeapRegionSet* proxy_set) {
-  hrl_assert_mt_safety_ok(this);
-  hrl_assert_mt_safety_ok(proxy_set);
-  hrl_assert_sets_match(this, proxy_set);
+  hrs_assert_mt_safety_ok(this);
+  hrs_assert_mt_safety_ok(proxy_set);
+  hrs_assert_sets_match(this, proxy_set);
 
   verify_optional();
   proxy_set->verify_optional();
@@ -231,19 +231,19 @@
   if (proxy_set->is_empty()) return;
 
   assert(proxy_set->length() <= _length,
-         hrl_err_msg("[%s] proxy set length: "SIZE_FORMAT" "
+         hrs_err_msg("[%s] proxy set length: "SIZE_FORMAT" "
                      "should be <= length: "SIZE_FORMAT,
                      name(), proxy_set->length(), _length));
   _length -= proxy_set->length();
 
   assert(proxy_set->region_num() <= _region_num,
-         hrl_err_msg("[%s] proxy set region num: "SIZE_FORMAT" "
+         hrs_err_msg("[%s] proxy set region num: "SIZE_FORMAT" "
                      "should be <= region num: "SIZE_FORMAT,
                      name(), proxy_set->region_num(), _region_num));
   _region_num -= proxy_set->region_num();
 
   assert(proxy_set->total_used_bytes() <= _total_used_bytes,
-         hrl_err_msg("[%s] proxy set used bytes: "SIZE_FORMAT" "
+         hrs_err_msg("[%s] proxy set used bytes: "SIZE_FORMAT" "
                      "should be <= used bytes: "SIZE_FORMAT,
                      name(), proxy_set->total_used_bytes(),
                      _total_used_bytes));
@@ -257,13 +257,13 @@
 
 //////////////////// HeapRegionLinkedList ////////////////////
 
-void HeapRegionLinkedList::fill_in_ext_msg_extra(hrl_ext_msg* msg) {
+void HeapRegionLinkedList::fill_in_ext_msg_extra(hrs_ext_msg* msg) {
   msg->append(" hd: "PTR_FORMAT" tl: "PTR_FORMAT, head(), tail());
 }
 
 void HeapRegionLinkedList::add_as_tail(HeapRegionLinkedList* from_list) {
-  hrl_assert_mt_safety_ok(this);
-  hrl_assert_mt_safety_ok(from_list);
+  hrs_assert_mt_safety_ok(this);
+  hrs_assert_mt_safety_ok(from_list);
 
   verify_optional();
   from_list->verify_optional();
@@ -283,10 +283,10 @@
 #endif // ASSERT
 
   if (_tail != NULL) {
-    assert(length() >  0 && _head != NULL, hrl_ext_msg(this, "invariant"));
+    assert(length() >  0 && _head != NULL, hrs_ext_msg(this, "invariant"));
     _tail->set_next(from_list->_head);
   } else {
-    assert(length() == 0 && _head == NULL, hrl_ext_msg(this, "invariant"));
+    assert(length() == 0 && _head == NULL, hrs_ext_msg(this, "invariant"));
     _head = from_list->_head;
   }
   _tail = from_list->_tail;
@@ -301,12 +301,12 @@
 }
 
 void HeapRegionLinkedList::remove_all() {
-  hrl_assert_mt_safety_ok(this);
+  hrs_assert_mt_safety_ok(this);
   verify_optional();
 
   HeapRegion* curr = _head;
   while (curr != NULL) {
-    hrl_assert_region_ok(this, curr, this);
+    hrs_assert_region_ok(this, curr, this);
 
     HeapRegion* next = curr->next();
     curr->set_next(NULL);
@@ -319,9 +319,9 @@
 }
 
 void HeapRegionLinkedList::remove_all_pending(size_t target_count) {
-  hrl_assert_mt_safety_ok(this);
-  assert(target_count > 1, hrl_ext_msg(this, "pre-condition"));
-  assert(!is_empty(), hrl_ext_msg(this, "pre-condition"));
+  hrs_assert_mt_safety_ok(this);
+  assert(target_count > 1, hrs_ext_msg(this, "pre-condition"));
+  assert(!is_empty(), hrs_ext_msg(this, "pre-condition"));
 
   verify_optional();
   DEBUG_ONLY(size_t old_length = length();)
@@ -330,27 +330,27 @@
   HeapRegion* prev = NULL;
   size_t count = 0;
   while (curr != NULL) {
-    hrl_assert_region_ok(this, curr, this);
+    hrs_assert_region_ok(this, curr, this);
     HeapRegion* next = curr->next();
 
     if (curr->pending_removal()) {
       assert(count < target_count,
-             hrl_err_msg("[%s] should not come across more regions "
+             hrs_err_msg("[%s] should not come across more regions "
                          "pending for removal than target_count: "SIZE_FORMAT,
                          name(), target_count));
 
       if (prev == NULL) {
-        assert(_head == curr, hrl_ext_msg(this, "invariant"));
+        assert(_head == curr, hrs_ext_msg(this, "invariant"));
         _head = next;
       } else {
-        assert(_head != curr, hrl_ext_msg(this, "invariant"));
+        assert(_head != curr, hrs_ext_msg(this, "invariant"));
         prev->set_next(next);
       }
       if (next == NULL) {
-        assert(_tail == curr, hrl_ext_msg(this, "invariant"));
+        assert(_tail == curr, hrs_ext_msg(this, "invariant"));
         _tail = prev;
       } else {
-        assert(_tail != curr, hrl_ext_msg(this, "invariant"));
+        assert(_tail != curr, hrs_ext_msg(this, "invariant"));
       }
 
       curr->set_next(NULL);
@@ -371,10 +371,10 @@
   }
 
   assert(count == target_count,
-         hrl_err_msg("[%s] count: "SIZE_FORMAT" should be == "
+         hrs_err_msg("[%s] count: "SIZE_FORMAT" should be == "
                      "target_count: "SIZE_FORMAT, name(), count, target_count));
   assert(length() + target_count == old_length,
-         hrl_err_msg("[%s] new length should be consistent "
+         hrs_err_msg("[%s] new length should be consistent "
                      "new length: "SIZE_FORMAT" old length: "SIZE_FORMAT" "
                      "target_count: "SIZE_FORMAT,
                      name(), length(), old_length, target_count));
@@ -385,7 +385,7 @@
 void HeapRegionLinkedList::verify() {
   // See comment in HeapRegionSetBase::verify() about MT safety and
   // verification.
-  hrl_assert_mt_safety_ok(this);
+  hrs_assert_mt_safety_ok(this);
 
   // This will also do the basic verification too.
   verify_start();
@@ -399,7 +399,7 @@
 
     count += 1;
     guarantee(count < _unrealistically_long_length,
-              hrl_err_msg("[%s] the calculated length: "SIZE_FORMAT" "
+              hrs_err_msg("[%s] the calculated length: "SIZE_FORMAT" "
                           "seems very long, is there maybe a cycle? "
                           "curr: "PTR_FORMAT" prev0: "PTR_FORMAT" "
                           "prev1: "PTR_FORMAT" length: "SIZE_FORMAT,
@@ -410,7 +410,7 @@
     curr  = curr->next();
   }
 
-  guarantee(_tail == prev0, hrl_ext_msg(this, "post-condition"));
+  guarantee(_tail == prev0, hrs_ext_msg(this, "post-condition"));
 
   verify_end();
 }
--- a/src/share/vm/gc_implementation/g1/heapRegionSet.hpp	Thu Mar 03 21:02:56 2011 -0800
+++ b/src/share/vm/gc_implementation/g1/heapRegionSet.hpp	Fri Mar 04 17:13:19 2011 -0500
@@ -28,8 +28,8 @@
 #include "gc_implementation/g1/heapRegion.hpp"
 
 // Large buffer for some cases where the output might be larger than normal.
-#define HRL_ERR_MSG_BUFSZ 512
-typedef FormatBuffer<HRL_ERR_MSG_BUFSZ> hrl_err_msg;
+#define HRS_ERR_MSG_BUFSZ 512
+typedef FormatBuffer<HRS_ERR_MSG_BUFSZ> hrs_err_msg;
 
 // Set verification will be forced either if someone defines
 // HEAP_REGION_SET_FORCE_VERIFY to be 1, or in builds in which
@@ -45,10 +45,10 @@
 // (e.g., length, region num, used bytes sum) plus any shared
 // functionality (e.g., verification).
 
-class hrl_ext_msg;
+class hrs_ext_msg;
 
 class HeapRegionSetBase VALUE_OBJ_CLASS_SPEC {
-  friend class hrl_ext_msg;
+  friend class hrs_ext_msg;
 
 protected:
   static size_t calculate_region_num(HeapRegion* hr);
@@ -104,10 +104,10 @@
   virtual bool check_mt_safety() { return true; }
 
   // fill_in_ext_msg() writes the the values of the set's attributes
-  // in the custom err_msg (hrl_ext_msg). fill_in_ext_msg_extra()
+  // in the custom err_msg (hrs_ext_msg). fill_in_ext_msg_extra()
   // allows subclasses to append further information.
-  virtual void fill_in_ext_msg_extra(hrl_ext_msg* msg) { }
-  void fill_in_ext_msg(hrl_ext_msg* msg, const char* message);
+  virtual void fill_in_ext_msg_extra(hrs_ext_msg* msg) { }
+  void fill_in_ext_msg(hrs_ext_msg* msg, const char* message);
 
   // It updates the fields of the set to reflect hr being added to
   // the set.
@@ -170,9 +170,9 @@
 // the fields of the associated set. This can be very helpful in
 // diagnosing failures.
 
-class hrl_ext_msg : public hrl_err_msg {
+class hrs_ext_msg : public hrs_err_msg {
 public:
-  hrl_ext_msg(HeapRegionSetBase* set, const char* message) : hrl_err_msg("") {
+  hrs_ext_msg(HeapRegionSetBase* set, const char* message) : hrs_err_msg("") {
     set->fill_in_ext_msg(this, message);
   }
 };
@@ -180,25 +180,25 @@
 // These two macros are provided for convenience, to keep the uses of
 // these two asserts a bit more concise.
 
-#define hrl_assert_mt_safety_ok(_set_)                                        \
+#define hrs_assert_mt_safety_ok(_set_)                                        \
   do {                                                                        \
-    assert((_set_)->check_mt_safety(), hrl_ext_msg((_set_), "MT safety"));    \
+    assert((_set_)->check_mt_safety(), hrs_ext_msg((_set_), "MT safety"));    \
   } while (0)
 
-#define hrl_assert_region_ok(_set_, _hr_, _expected_)                         \
+#define hrs_assert_region_ok(_set_, _hr_, _expected_)                         \
   do {                                                                        \
     assert((_set_)->verify_region((_hr_), (_expected_)),                      \
-           hrl_ext_msg((_set_), "region verification"));                      \
+           hrs_ext_msg((_set_), "region verification"));                      \
   } while (0)
 
 //////////////////// HeapRegionSet ////////////////////
 
-#define hrl_assert_sets_match(_set1_, _set2_)                                 \
+#define hrs_assert_sets_match(_set1_, _set2_)                                 \
   do {                                                                        \
     assert(((_set1_)->regions_humongous() ==                                  \
                                             (_set2_)->regions_humongous()) && \
            ((_set1_)->regions_empty() == (_set2_)->regions_empty()),          \
-           hrl_err_msg("the contents of set %s and set %s should match",      \
+           hrs_err_msg("the contents of set %s and set %s should match",      \
                        (_set1_)->name(), (_set2_)->name()));                  \
   } while (0)
 
@@ -267,7 +267,7 @@
   HeapRegion* tail() { return _tail; }
 
 protected:
-  virtual void fill_in_ext_msg_extra(hrl_ext_msg* msg);
+  virtual void fill_in_ext_msg_extra(hrs_ext_msg* msg);
 
   // See the comment for HeapRegionSetBase::clear()
   virtual void clear();
@@ -309,10 +309,10 @@
   virtual void print_on(outputStream* out, bool print_contents = false);
 };
 
-//////////////////// HeapRegionLinkedList ////////////////////
+//////////////////// HeapRegionLinkedListIterator ////////////////////
 
-// Iterator class that provides a convenient way to iterator over the
-// regions in a HeapRegionLinkedList instance.
+// Iterator class that provides a convenient way to iterate over the
+// regions of a HeapRegionLinkedList instance.
 
 class HeapRegionLinkedListIterator : public StackObj {
 private:
--- a/src/share/vm/gc_implementation/g1/heapRegionSet.inline.hpp	Thu Mar 03 21:02:56 2011 -0800
+++ b/src/share/vm/gc_implementation/g1/heapRegionSet.inline.hpp	Fri Mar 04 17:13:19 2011 -0500
@@ -42,8 +42,8 @@
 }
 
 inline void HeapRegionSetBase::add_internal(HeapRegion* hr) {
-  hrl_assert_region_ok(this, hr, NULL);
-  assert(hr->next() == NULL, hrl_ext_msg(this, "should not already be linked"));
+  hrs_assert_region_ok(this, hr, NULL);
+  assert(hr->next() == NULL, hrs_ext_msg(this, "should not already be linked"));
 
   update_for_addition(hr);
   hr->set_containing_set(this);
@@ -51,7 +51,7 @@
 
 inline void HeapRegionSetBase::update_for_removal(HeapRegion* hr) {
   // Assumes the caller has already verified the region.
-  assert(_length > 0, hrl_ext_msg(this, "pre-condition"));
+  assert(_length > 0, hrs_ext_msg(this, "pre-condition"));
   _length -= 1;
 
   size_t region_num_diff;
@@ -61,22 +61,22 @@
     region_num_diff = calculate_region_num(hr);
   }
   assert(region_num_diff <= _region_num,
-         hrl_err_msg("[%s] region's region num: "SIZE_FORMAT" "
+         hrs_err_msg("[%s] region's region num: "SIZE_FORMAT" "
                      "should be <= region num: "SIZE_FORMAT,
                      name(), region_num_diff, _region_num));
   _region_num -= region_num_diff;
 
   size_t used_bytes = hr->used();
   assert(used_bytes <= _total_used_bytes,
-         hrl_err_msg("[%s] region's used bytes: "SIZE_FORMAT" "
+         hrs_err_msg("[%s] region's used bytes: "SIZE_FORMAT" "
                      "should be <= used bytes: "SIZE_FORMAT,
                      name(), used_bytes, _total_used_bytes));
   _total_used_bytes -= used_bytes;
 }
 
 inline void HeapRegionSetBase::remove_internal(HeapRegion* hr) {
-  hrl_assert_region_ok(this, hr, this);
-  assert(hr->next() == NULL, hrl_ext_msg(this, "should already be unlinked"));
+  hrs_assert_region_ok(this, hr, this);
+  assert(hr->next() == NULL, hrs_ext_msg(this, "should already be unlinked"));
 
   hr->set_containing_set(NULL);
   update_for_removal(hr);
@@ -85,13 +85,13 @@
 //////////////////// HeapRegionSet ////////////////////
 
 inline void HeapRegionSet::add(HeapRegion* hr) {
-  hrl_assert_mt_safety_ok(this);
+  hrs_assert_mt_safety_ok(this);
   // add_internal() will verify the region.
   add_internal(hr);
 }
 
 inline void HeapRegionSet::remove(HeapRegion* hr) {
-  hrl_assert_mt_safety_ok(this);
+  hrs_assert_mt_safety_ok(this);
   // remove_internal() will verify the region.
   remove_internal(hr);
 }
@@ -101,8 +101,8 @@
   // No need to fo the MT safety check here given that this method
   // does not update the contents of the set but instead accumulates
   // the changes in proxy_set which is assumed to be thread-local.
-  hrl_assert_sets_match(this, proxy_set);
-  hrl_assert_region_ok(this, hr, this);
+  hrs_assert_sets_match(this, proxy_set);
+  hrs_assert_region_ok(this, hr, this);
 
   hr->set_containing_set(NULL);
   proxy_set->update_for_addition(hr);
@@ -111,10 +111,10 @@
 //////////////////// HeapRegionLinkedList ////////////////////
 
 inline void HeapRegionLinkedList::add_as_tail(HeapRegion* hr) {
-  hrl_assert_mt_safety_ok(this);
+  hrs_assert_mt_safety_ok(this);
   assert((length() == 0 && _head == NULL && _tail == NULL) ||
          (length() >  0 && _head != NULL && _tail != NULL),
-         hrl_ext_msg(this, "invariant"));
+         hrs_ext_msg(this, "invariant"));
   // add_internal() will verify the region.
   add_internal(hr);
 
@@ -128,10 +128,10 @@
 }
 
 inline HeapRegion* HeapRegionLinkedList::remove_head() {
-  hrl_assert_mt_safety_ok(this);
-  assert(!is_empty(), hrl_ext_msg(this, "the list should not be empty"));
+  hrs_assert_mt_safety_ok(this);
+  assert(!is_empty(), hrs_ext_msg(this, "the list should not be empty"));
   assert(length() > 0 && _head != NULL && _tail != NULL,
-         hrl_ext_msg(this, "invariant"));
+         hrs_ext_msg(this, "invariant"));
 
   // We need to unlink it first.
   HeapRegion* hr = _head;
@@ -147,7 +147,7 @@
 }
 
 inline HeapRegion* HeapRegionLinkedList::remove_head_or_null() {
-  hrl_assert_mt_safety_ok(this);
+  hrs_assert_mt_safety_ok(this);
 
   if (!is_empty()) {
     return remove_head();
--- a/src/share/vm/gc_implementation/g1/heapRegionSets.cpp	Thu Mar 03 21:02:56 2011 -0800
+++ b/src/share/vm/gc_implementation/g1/heapRegionSets.cpp	Fri Mar 04 17:13:19 2011 -0500
@@ -52,7 +52,7 @@
                                             FreeList_lock->owned_by_self())) ||
             (!SafepointSynchronize::is_at_safepoint() &&
                                                 Heap_lock->owned_by_self()),
-            hrl_ext_msg(this, "master free list MT safety protocol"));
+            hrs_ext_msg(this, "master free list MT safety protocol"));
 
   return FreeRegionList::check_mt_safety();
 }
@@ -65,7 +65,7 @@
   // while holding the SecondaryFreeList_lock.
 
   guarantee(SecondaryFreeList_lock->owned_by_self(),
-            hrl_ext_msg(this, "secondary free list MT safety protocol"));
+            hrs_ext_msg(this, "secondary free list MT safety protocol"));
 
   return FreeRegionList::check_mt_safety();
 }
@@ -81,7 +81,7 @@
   return HeapRegionSet::verify_region_extra(hr);
 }
 
-//////////////////// HumongousRegionSet ////////////////////
+//////////////////// MasterHumongousRegionSet ////////////////////
 
 bool MasterHumongousRegionSet::check_mt_safety() {
   // Master Humongous Set MT safety protocol:
@@ -97,6 +97,6 @@
                                              OldSets_lock->owned_by_self())) ||
             (!SafepointSynchronize::is_at_safepoint() &&
                                                  Heap_lock->owned_by_self()),
-            hrl_ext_msg(this, "master humongous set MT safety protocol"));
+            hrs_ext_msg(this, "master humongous set MT safety protocol"));
   return HumongousRegionSet::check_mt_safety();
 }
--- a/src/share/vm/utilities/debug.hpp	Thu Mar 03 21:02:56 2011 -0800
+++ b/src/share/vm/utilities/debug.hpp	Fri Mar 04 17:13:19 2011 -0500
@@ -25,6 +25,7 @@
 #ifndef SHARE_VM_UTILITIES_DEBUG_HPP
 #define SHARE_VM_UTILITIES_DEBUG_HPP
 
+#include "prims/jvm.h"
 #include "utilities/globalDefinitions.hpp"
 
 #include <stdarg.h>
@@ -48,7 +49,7 @@
 FormatBuffer<bufsz>::FormatBuffer(const char * format, ...) {
   va_list argp;
   va_start(argp, format);
-  vsnprintf(_buf, bufsz, format, argp);
+  jio_vsnprintf(_buf, bufsz, format, argp);
   va_end(argp);
 }
 
@@ -61,7 +62,7 @@
 
   va_list argp;
   va_start(argp, format);
-  vsnprintf(buf_end, bufsz - len, format, argp);
+  jio_vsnprintf(buf_end, bufsz - len, format, argp);
   va_end(argp);
 }
 
--- a/src/share/vm/utilities/globalDefinitions.hpp	Thu Mar 03 21:02:56 2011 -0800
+++ b/src/share/vm/utilities/globalDefinitions.hpp	Fri Mar 04 17:13:19 2011 -0500
@@ -1185,7 +1185,7 @@
 // '%d' formats to indicate a 64-bit quantity; commonly "l" (in LP64) or "ll"
 // (in ILP32).
 
-#define BOOL_TO_STR(__b) (__b) ? "true" : "false"
+#define BOOL_TO_STR(_b_) ((_b_) ? "true" : "false")
 
 // Format 32-bit quantities.
 #define INT32_FORMAT  "%d"