From dcf65a3ccf88d42f61f8471817cc385c4208eb77 Mon Sep 17 00:00:00 2001
From: brutisso <unknown>
Date: Sun, 10 Feb 2013 21:15:16 +0100
Subject: [PATCH] 8002144: G1: large number of evacuation failures may lead to
 large c heap memory usage Summary: Use Stack<> instead of GrowableArray to
 keep track of preserved marks. Also reviewed by vitalyd@gmail.com.
 Reviewed-by: johnc, jcoomes

---
 .../gc_implementation/g1/g1CollectedHeap.cpp  | 35 ++++++-------------
 .../gc_implementation/g1/g1CollectedHeap.hpp  |  8 ++---
 2 files changed, 14 insertions(+), 29 deletions(-)

diff --git a/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp b/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp
index cc11754c9a..6464797904 100644
--- a/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp
@@ -1893,7 +1893,6 @@ G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
   _ref_processor_stw(NULL),
   _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
   _bot_shared(NULL),
-  _objs_with_preserved_marks(NULL), _preserved_marks_of_objs(NULL),
   _evac_failure_scan_stack(NULL) ,
   _mark_in_progress(false),
   _cg1r(NULL), _summary_bytes_used(0),
@@ -4215,22 +4214,15 @@ void G1CollectedHeap::remove_self_forwarding_pointers() {
   assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
 
   // Now restore saved marks, if any.
-  if (_objs_with_preserved_marks != NULL) {
-    assert(_preserved_marks_of_objs != NULL, "Both or none.");
-    guarantee(_objs_with_preserved_marks->length() ==
-              _preserved_marks_of_objs->length(), "Both or none.");
-    for (int i = 0; i < _objs_with_preserved_marks->length(); i++) {
-      oop obj   = _objs_with_preserved_marks->at(i);
-      markOop m = _preserved_marks_of_objs->at(i);
-      obj->set_mark(m);
-    }
-
-    // Delete the preserved marks growable arrays (allocated on the C heap).
-    delete _objs_with_preserved_marks;
-    delete _preserved_marks_of_objs;
-    _objs_with_preserved_marks = NULL;
-    _preserved_marks_of_objs = NULL;
+  assert(_objs_with_preserved_marks.size() ==
+            _preserved_marks_of_objs.size(), "Both or none.");
+  while (!_objs_with_preserved_marks.is_empty()) {
+    oop obj = _objs_with_preserved_marks.pop();
+    markOop m = _preserved_marks_of_objs.pop();
+    obj->set_mark(m);
   }
+  _objs_with_preserved_marks.clear(true);
+  _preserved_marks_of_objs.clear(true);
 }
 
 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
@@ -4313,15 +4305,8 @@ void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
   // We want to call the "for_promotion_failure" version only in the
   // case of a promotion failure.
   if (m->must_be_preserved_for_promotion_failure(obj)) {
-    if (_objs_with_preserved_marks == NULL) {
-      assert(_preserved_marks_of_objs == NULL, "Both or none.");
-      _objs_with_preserved_marks =
-        new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
-      _preserved_marks_of_objs =
-        new (ResourceObj::C_HEAP, mtGC) GrowableArray<markOop>(40, true);
-    }
-    _objs_with_preserved_marks->push(obj);
-    _preserved_marks_of_objs->push(m);
+    _objs_with_preserved_marks.push(obj);
+    _preserved_marks_of_objs.push(m);
   }
 }
 
diff --git a/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp b/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp
index 816d4f253a..7dc5bd8304 100644
--- a/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp
@@ -37,6 +37,7 @@
 #include "memory/barrierSet.hpp"
 #include "memory/memRegion.hpp"
 #include "memory/sharedHeap.hpp"
+#include "utilities/stack.hpp"
 
 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
 // It uses the "Garbage First" heap organization and algorithm, which
@@ -877,10 +878,9 @@ protected:
   // forwarding pointers to themselves.  Reset them.
   void remove_self_forwarding_pointers();
 
-  // When one is non-null, so is the other.  Together, they each pair is
-  // an object with a preserved mark, and its mark value.
-  GrowableArray<oop>*     _objs_with_preserved_marks;
-  GrowableArray<markOop>* _preserved_marks_of_objs;
+  // Together, these store an object with a preserved mark, and its mark value.
+  Stack<oop, mtGC>     _objs_with_preserved_marks;
+  Stack<markOop, mtGC> _preserved_marks_of_objs;
 
   // Preserve the mark of "obj", if necessary, in preparation for its mark
   // word being overwritten with a self-forwarding-pointer.
-- 
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