8008508: CMS does not correctly reduce heap size after a Full GC

Reviewed-by: johnc, ysr

hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp

@@ -48,6 +48,7 @@
 #include "memory/iterator.hpp"
 #include "memory/referencePolicy.hpp"
 #include "memory/resourceArea.hpp"
+#include "memory/tenuredGeneration.hpp"
 #include "oops/oop.inline.hpp"
 #include "prims/jvmtiExport.hpp"
 #include "runtime/globals_extension.hpp"
@@ -916,7 +917,31 @@ void ConcurrentMarkSweepGeneration::compute_new_size() {
     return;
   }
 
-  size_t expand_bytes = 0;
+  // Compute some numbers about the state of the heap.
+  const size_t used_after_gc = used();
+  const size_t capacity_after_gc = capacity();
+
+  CardGeneration::compute_new_size();
+
+  // Reset again after a possible resizing
+  cmsSpace()->reset_after_compaction();
+
+  assert(used() == used_after_gc && used_after_gc <= capacity(),
+         err_msg("used: " SIZE_FORMAT " used_after_gc: " SIZE_FORMAT
+         " capacity: " SIZE_FORMAT, used(), used_after_gc, capacity()));
+}
+
+void ConcurrentMarkSweepGeneration::compute_new_size_free_list() {
+  assert_locked_or_safepoint(Heap_lock);
+
+  // If incremental collection failed, we just want to expand
+  // to the limit.
+  if (incremental_collection_failed()) {
+    clear_incremental_collection_failed();
+    grow_to_reserved();
+    return;
+  }
+
   double free_percentage = ((double) free()) / capacity();
   double desired_free_percentage = (double) MinHeapFreeRatio / 100;
   double maximum_free_percentage = (double) MaxHeapFreeRatio / 100;
@@ -925,9 +950,7 @@ void ConcurrentMarkSweepGeneration::compute_new_size() {
   if (free_percentage < desired_free_percentage) {
     size_t desired_capacity = (size_t)(used() / ((double) 1 - desired_free_percentage));
     assert(desired_capacity >= capacity(), "invalid expansion size");
-    expand_bytes = MAX2(desired_capacity - capacity(), MinHeapDeltaBytes);
+    size_t expand_bytes = MAX2(desired_capacity - capacity(), MinHeapDeltaBytes);
-  }
-  if (expand_bytes > 0) {
     if (PrintGCDetails && Verbose) {
       size_t desired_capacity = (size_t)(used() / ((double) 1 - desired_free_percentage));
       gclog_or_tty->print_cr("\nFrom compute_new_size: ");
@@ -961,6 +984,14 @@ void ConcurrentMarkSweepGeneration::compute_new_size() {
       gclog_or_tty->print_cr("  Expanded free fraction %f",
         ((double) free()) / capacity());
     }
+  } else {
+    size_t desired_capacity = (size_t)(used() / ((double) 1 - desired_free_percentage));
+    assert(desired_capacity <= capacity(), "invalid expansion size");
+    size_t shrink_bytes = capacity() - desired_capacity;
+    // Don't shrink unless the delta is greater than the minimum shrink we want
+    if (shrink_bytes >= MinHeapDeltaBytes) {
+      shrink_free_list_by(shrink_bytes);
+    }
   }
 }
 
@@ -1872,7 +1903,7 @@ void CMSCollector::compute_new_size() {
   assert_locked_or_safepoint(Heap_lock);
   FreelistLocker z(this);
   MetaspaceGC::compute_new_size();
-  _cmsGen->compute_new_size();
+  _cmsGen->compute_new_size_free_list();
 }
 
 // A work method used by foreground collection to determine
@@ -2601,6 +2632,10 @@ void CMSCollector::gc_prologue(bool full) {
 }
 
 void ConcurrentMarkSweepGeneration::gc_prologue(bool full) {
+
+  _capacity_at_prologue = capacity();
+  _used_at_prologue = used();
+
   // Delegate to CMScollector which knows how to coordinate between
   // this and any other CMS generations that it is responsible for
   // collecting.
@@ -3300,6 +3335,26 @@ bool ConcurrentMarkSweepGeneration::expand_and_ensure_spooling_space(
 }
 
 
+void ConcurrentMarkSweepGeneration::shrink_by(size_t bytes) {
+  assert_locked_or_safepoint(ExpandHeap_lock);
+  // Shrink committed space
+  _virtual_space.shrink_by(bytes);
+  // Shrink space; this also shrinks the space's BOT
+  _cmsSpace->set_end((HeapWord*) _virtual_space.high());
+  size_t new_word_size = heap_word_size(_cmsSpace->capacity());
+  // Shrink the shared block offset array
+  _bts->resize(new_word_size);
+  MemRegion mr(_cmsSpace->bottom(), new_word_size);
+  // Shrink the card table
+  Universe::heap()->barrier_set()->resize_covered_region(mr);
+
+  if (Verbose && PrintGC) {
+    size_t new_mem_size = _virtual_space.committed_size();
+    size_t old_mem_size = new_mem_size + bytes;
+    gclog_or_tty->print_cr("Shrinking %s from " SIZE_FORMAT "K to " SIZE_FORMAT "K",
+                  name(), old_mem_size/K, new_mem_size/K);
+  }
+}
 
 void ConcurrentMarkSweepGeneration::shrink(size_t bytes) {
   assert_locked_or_safepoint(Heap_lock);
@@ -3351,7 +3406,7 @@ bool ConcurrentMarkSweepGeneration::grow_to_reserved() {
   return success;
 }
 
-void ConcurrentMarkSweepGeneration::shrink_by(size_t bytes) {
+void ConcurrentMarkSweepGeneration::shrink_free_list_by(size_t bytes) {
   assert_locked_or_safepoint(Heap_lock);
   assert_lock_strong(freelistLock());
   // XXX Fix when compaction is implemented.
@@ -9074,51 +9129,6 @@ void ASConcurrentMarkSweepGeneration::update_counters(size_t used) {
   }
 }
 
-// The desired expansion delta is computed so that:
-// . desired free percentage or greater is used
-void ASConcurrentMarkSweepGeneration::compute_new_size() {
-  assert_locked_or_safepoint(Heap_lock);
-
-  GenCollectedHeap* gch = (GenCollectedHeap*) GenCollectedHeap::heap();
-
-  // If incremental collection failed, we just want to expand
-  // to the limit.
-  if (incremental_collection_failed()) {
-    clear_incremental_collection_failed();
-    grow_to_reserved();
-    return;
-  }
-
-  assert(UseAdaptiveSizePolicy, "Should be using adaptive sizing");
-
-  assert(gch->kind() == CollectedHeap::GenCollectedHeap,
-    "Wrong type of heap");
-  int prev_level = level() - 1;
-  assert(prev_level >= 0, "The cms generation is the lowest generation");
-  Generation* prev_gen = gch->get_gen(prev_level);
-  assert(prev_gen->kind() == Generation::ASParNew,
-    "Wrong type of young generation");
-  ParNewGeneration* younger_gen = (ParNewGeneration*) prev_gen;
-  size_t cur_eden = younger_gen->eden()->capacity();
-  CMSAdaptiveSizePolicy* size_policy = cms_size_policy();
-  size_t cur_promo = free();
-  size_policy->compute_tenured_generation_free_space(cur_promo,
-                                                       max_available(),
-                                                       cur_eden);
-  resize(cur_promo, size_policy->promo_size());
-
-  // Record the new size of the space in the cms generation
-  // that is available for promotions.  This is temporary.
-  // It should be the desired promo size.
-  size_policy->avg_cms_promo()->sample(free());
-  size_policy->avg_old_live()->sample(used());
-
-  if (UsePerfData) {
-    CMSGCAdaptivePolicyCounters* counters = gc_adaptive_policy_counters();
-    counters->update_cms_capacity_counter(capacity());
-  }
-}
-
 void ASConcurrentMarkSweepGeneration::shrink_by(size_t desired_bytes) {
   assert_locked_or_safepoint(Heap_lock);
   assert_lock_strong(freelistLock());

hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.hpp

@@ -60,6 +60,7 @@ class CompactibleFreeListSpace;
 class FreeChunk;
 class PromotionInfo;
 class ScanMarkedObjectsAgainCarefullyClosure;
+class TenuredGeneration;
 
 // A generic CMS bit map. It's the basis for both the CMS marking bit map
 // as well as for the mod union table (in each case only a subset of the
@@ -810,9 +811,6 @@ class CMSCollector: public CHeapObj<mtGC> {
   // used regions of each generation to limit the extent of sweep
   void save_sweep_limits();
 
-  // Resize the generations included in the collector.
-  void compute_new_size();
-
   // A work method used by foreground collection to determine
   // what type of collection (compacting or not, continuing or fresh)
   // it should do.
@@ -909,6 +907,9 @@ class CMSCollector: public CHeapObj<mtGC> {
   void releaseFreelistLocks() const;
   bool haveFreelistLocks() const;
 
+  // Adjust size of underlying generation
+  void compute_new_size();
+
   // GC prologue and epilogue
   void gc_prologue(bool full);
   void gc_epilogue(bool full);
@@ -1082,7 +1083,7 @@ class ConcurrentMarkSweepGeneration: public CardGeneration {
 
  protected:
   // Shrink generation by specified size (returns false if unable to shrink)
-  virtual void shrink_by(size_t bytes);
+  void shrink_free_list_by(size_t bytes);
 
   // Update statistics for GC
   virtual void update_gc_stats(int level, bool full);
@@ -1233,6 +1234,7 @@ class ConcurrentMarkSweepGeneration: public CardGeneration {
     CMSExpansionCause::Cause cause);
   virtual bool expand(size_t bytes, size_t expand_bytes);
   void shrink(size_t bytes);
+  void shrink_by(size_t bytes);
   HeapWord* expand_and_par_lab_allocate(CMSParGCThreadState* ps, size_t word_sz);
   bool expand_and_ensure_spooling_space(PromotionInfo* promo);
 
@@ -1293,7 +1295,13 @@ class ConcurrentMarkSweepGeneration: public CardGeneration {
   bool must_be_youngest() const { return false; }
   bool must_be_oldest()   const { return true; }
 
-  void compute_new_size();
+  // Resize the generation after a compacting GC.  The
+  // generation can be treated as a contiguous space
+  // after the compaction.
+  virtual void compute_new_size();
+  // Resize the generation after a non-compacting
+  // collection.
+  void compute_new_size_free_list();
 
   CollectionTypes debug_collection_type() { return _debug_collection_type; }
   void rotate_debug_collection_type();
@@ -1315,7 +1323,6 @@ class ASConcurrentMarkSweepGeneration : public ConcurrentMarkSweepGeneration {
   virtual void shrink_by(size_t bytes);
 
  public:
-  virtual void compute_new_size();
   ASConcurrentMarkSweepGeneration(ReservedSpace rs, size_t initial_byte_size,
                                   int level, CardTableRS* ct,
                                   bool use_adaptive_freelists,

hotspot/src/share/vm/memory/generation.cpp

@@ -382,7 +382,9 @@ void Generation::compact() {
 CardGeneration::CardGeneration(ReservedSpace rs, size_t initial_byte_size,
                                int level,
                                GenRemSet* remset) :
-  Generation(rs, initial_byte_size, level), _rs(remset)
+  Generation(rs, initial_byte_size, level), _rs(remset),
+  _shrink_factor(0), _min_heap_delta_bytes(), _capacity_at_prologue(),
+  _used_at_prologue()
 {
   HeapWord* start = (HeapWord*)rs.base();
   size_t reserved_byte_size = rs.size();
@@ -406,6 +408,9 @@ CardGeneration::CardGeneration(ReservedSpace rs, size_t initial_byte_size,
     // the end if we try.
     guarantee(_rs->is_aligned(reserved_mr.end()), "generation must be card aligned");
   }
+  _min_heap_delta_bytes = MinHeapDeltaBytes;
+  _capacity_at_prologue = initial_byte_size;
+  _used_at_prologue = 0;
 }
 
 bool CardGeneration::expand(size_t bytes, size_t expand_bytes) {
@@ -457,6 +462,160 @@ void CardGeneration::invalidate_remembered_set() {
 }
 
 
+void CardGeneration::compute_new_size() {
+  assert(_shrink_factor <= 100, "invalid shrink factor");
+  size_t current_shrink_factor = _shrink_factor;
+  _shrink_factor = 0;
+
+  // We don't have floating point command-line arguments
+  // Note:  argument processing ensures that MinHeapFreeRatio < 100.
+  const double minimum_free_percentage = MinHeapFreeRatio / 100.0;
+  const double maximum_used_percentage = 1.0 - minimum_free_percentage;
+
+  // Compute some numbers about the state of the heap.
+  const size_t used_after_gc = used();
+  const size_t capacity_after_gc = capacity();
+
+  const double min_tmp = used_after_gc / maximum_used_percentage;
+  size_t minimum_desired_capacity = (size_t)MIN2(min_tmp, double(max_uintx));
+  // Don't shrink less than the initial generation size
+  minimum_desired_capacity = MAX2(minimum_desired_capacity,
+                                  spec()->init_size());
+  assert(used_after_gc <= minimum_desired_capacity, "sanity check");
+
+  if (PrintGC && Verbose) {
+    const size_t free_after_gc = free();
+    const double free_percentage = ((double)free_after_gc) / capacity_after_gc;
+    gclog_or_tty->print_cr("TenuredGeneration::compute_new_size: ");
+    gclog_or_tty->print_cr("  "
+                  "  minimum_free_percentage: %6.2f"
+                  "  maximum_used_percentage: %6.2f",
+                  minimum_free_percentage,
+                  maximum_used_percentage);
+    gclog_or_tty->print_cr("  "
+                  "   free_after_gc   : %6.1fK"
+                  "   used_after_gc   : %6.1fK"
+                  "   capacity_after_gc   : %6.1fK",
+                  free_after_gc / (double) K,
+                  used_after_gc / (double) K,
+                  capacity_after_gc / (double) K);
+    gclog_or_tty->print_cr("  "
+                  "   free_percentage: %6.2f",
+                  free_percentage);
+  }
+
+  if (capacity_after_gc < minimum_desired_capacity) {
+    // If we have less free space than we want then expand
+    size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
+    // Don't expand unless it's significant
+    if (expand_bytes >= _min_heap_delta_bytes) {
+      expand(expand_bytes, 0); // safe if expansion fails
+    }
+    if (PrintGC && Verbose) {
+      gclog_or_tty->print_cr("    expanding:"
+                    "  minimum_desired_capacity: %6.1fK"
+                    "  expand_bytes: %6.1fK"
+                    "  _min_heap_delta_bytes: %6.1fK",
+                    minimum_desired_capacity / (double) K,
+                    expand_bytes / (double) K,
+                    _min_heap_delta_bytes / (double) K);
+    }
+    return;
+  }
+
+  // No expansion, now see if we want to shrink
+  size_t shrink_bytes = 0;
+  // We would never want to shrink more than this
+  size_t max_shrink_bytes = capacity_after_gc - minimum_desired_capacity;
+
+  if (MaxHeapFreeRatio < 100) {
+    const double maximum_free_percentage = MaxHeapFreeRatio / 100.0;
+    const double minimum_used_percentage = 1.0 - maximum_free_percentage;
+    const double max_tmp = used_after_gc / minimum_used_percentage;
+    size_t maximum_desired_capacity = (size_t)MIN2(max_tmp, double(max_uintx));
+    maximum_desired_capacity = MAX2(maximum_desired_capacity,
+                                    spec()->init_size());
+    if (PrintGC && Verbose) {
+      gclog_or_tty->print_cr("  "
+                             "  maximum_free_percentage: %6.2f"
+                             "  minimum_used_percentage: %6.2f",
+                             maximum_free_percentage,
+                             minimum_used_percentage);
+      gclog_or_tty->print_cr("  "
+                             "  _capacity_at_prologue: %6.1fK"
+                             "  minimum_desired_capacity: %6.1fK"
+                             "  maximum_desired_capacity: %6.1fK",
+                             _capacity_at_prologue / (double) K,
+                             minimum_desired_capacity / (double) K,
+                             maximum_desired_capacity / (double) K);
+    }
+    assert(minimum_desired_capacity <= maximum_desired_capacity,
+           "sanity check");
+
+    if (capacity_after_gc > maximum_desired_capacity) {
+      // Capacity too large, compute shrinking size
+      shrink_bytes = capacity_after_gc - maximum_desired_capacity;
+      // We don't want shrink all the way back to initSize if people call
+      // System.gc(), because some programs do that between "phases" and then
+      // we'd just have to grow the heap up again for the next phase.  So we
+      // damp the shrinking: 0% on the first call, 10% on the second call, 40%
+      // on the third call, and 100% by the fourth call.  But if we recompute
+      // size without shrinking, it goes back to 0%.
+      shrink_bytes = shrink_bytes / 100 * current_shrink_factor;
+      assert(shrink_bytes <= max_shrink_bytes, "invalid shrink size");
+      if (current_shrink_factor == 0) {
+        _shrink_factor = 10;
+      } else {
+        _shrink_factor = MIN2(current_shrink_factor * 4, (size_t) 100);
+      }
+      if (PrintGC && Verbose) {
+        gclog_or_tty->print_cr("  "
+                      "  shrinking:"
+                      "  initSize: %.1fK"
+                      "  maximum_desired_capacity: %.1fK",
+                      spec()->init_size() / (double) K,
+                      maximum_desired_capacity / (double) K);
+        gclog_or_tty->print_cr("  "
+                      "  shrink_bytes: %.1fK"
+                      "  current_shrink_factor: %d"
+                      "  new shrink factor: %d"
+                      "  _min_heap_delta_bytes: %.1fK",
+                      shrink_bytes / (double) K,
+                      current_shrink_factor,
+                      _shrink_factor,
+                      _min_heap_delta_bytes / (double) K);
+      }
+    }
+  }
+
+  if (capacity_after_gc > _capacity_at_prologue) {
+    // We might have expanded for promotions, in which case we might want to
+    // take back that expansion if there's room after GC.  That keeps us from
+    // stretching the heap with promotions when there's plenty of room.
+    size_t expansion_for_promotion = capacity_after_gc - _capacity_at_prologue;
+    expansion_for_promotion = MIN2(expansion_for_promotion, max_shrink_bytes);
+    // We have two shrinking computations, take the largest
+    shrink_bytes = MAX2(shrink_bytes, expansion_for_promotion);
+    assert(shrink_bytes <= max_shrink_bytes, "invalid shrink size");
+    if (PrintGC && Verbose) {
+      gclog_or_tty->print_cr("  "
+                             "  aggressive shrinking:"
+                             "  _capacity_at_prologue: %.1fK"
+                             "  capacity_after_gc: %.1fK"
+                             "  expansion_for_promotion: %.1fK"
+                             "  shrink_bytes: %.1fK",
+                             capacity_after_gc / (double) K,
+                             _capacity_at_prologue / (double) K,
+                             expansion_for_promotion / (double) K,
+                             shrink_bytes / (double) K);
+    }
+  }
+  // Don't shrink unless it's significant
+  if (shrink_bytes >= _min_heap_delta_bytes) {
+    shrink(shrink_bytes);
+  }
+}
+
 // Currently nothing to do.
 void CardGeneration::prepare_for_verify() {}
 

hotspot/src/share/vm/memory/generation.hpp

@@ -634,6 +634,17 @@ class CardGeneration: public Generation {
   // This is local to this generation.
   BlockOffsetSharedArray* _bts;
 
+  // current shrinking effect: this damps shrinking when the heap gets empty.
+  size_t _shrink_factor;
+
+  size_t _min_heap_delta_bytes;   // Minimum amount to expand.
+
+  // Some statistics from before gc started.
+  // These are gathered in the gc_prologue (and should_collect)
+  // to control growing/shrinking policy in spite of promotions.
+  size_t _capacity_at_prologue;
+  size_t _used_at_prologue;
+
   CardGeneration(ReservedSpace rs, size_t initial_byte_size, int level,
                  GenRemSet* remset);
 
@@ -644,6 +655,11 @@ class CardGeneration: public Generation {
   // necessarily the full "bytes") was done.
   virtual bool expand(size_t bytes, size_t expand_bytes);
 
+  // Shrink generation with specified size (returns false if unable to shrink)
+  virtual void shrink(size_t bytes) = 0;
+
+  virtual void compute_new_size();
+
   virtual void clear_remembered_set();
 
   virtual void invalidate_remembered_set();
@@ -667,7 +683,6 @@ class OneContigSpaceCardGeneration: public CardGeneration {
   friend class VM_PopulateDumpSharedSpace;
 
  protected:
-  size_t     _min_heap_delta_bytes;   // Minimum amount to expand.
   ContiguousSpace*  _the_space;       // actual space holding objects
   WaterMark  _last_gc;                // watermark between objects allocated before
                                       // and after last GC.
@@ -688,11 +703,10 @@ class OneContigSpaceCardGeneration: public CardGeneration {
 
  public:
   OneContigSpaceCardGeneration(ReservedSpace rs, size_t initial_byte_size,
-                               size_t min_heap_delta_bytes,
                                int level, GenRemSet* remset,
                                ContiguousSpace* space) :
     CardGeneration(rs, initial_byte_size, level, remset),
-    _the_space(space), _min_heap_delta_bytes(min_heap_delta_bytes)
+    _the_space(space)
   {}
 
   inline bool is_in(const void* p) const;

hotspot/src/share/vm/memory/tenuredGeneration.cpp

@@ -39,7 +39,7 @@ TenuredGeneration::TenuredGeneration(ReservedSpace rs,
                                      size_t initial_byte_size, int level,
                                      GenRemSet* remset) :
   OneContigSpaceCardGeneration(rs, initial_byte_size,
-                               MinHeapDeltaBytes, level, remset, NULL)
+                               level, remset, NULL)
 {
   HeapWord* bottom = (HeapWord*) _virtual_space.low();
   HeapWord* end    = (HeapWord*) _virtual_space.high();
@@ -86,162 +86,6 @@ const char* TenuredGeneration::name() const {
   return "tenured generation";
 }
 
-void TenuredGeneration::compute_new_size() {
-  assert(_shrink_factor <= 100, "invalid shrink factor");
-  size_t current_shrink_factor = _shrink_factor;
-  _shrink_factor = 0;
-
-  // We don't have floating point command-line arguments
-  // Note:  argument processing ensures that MinHeapFreeRatio < 100.
-  const double minimum_free_percentage = MinHeapFreeRatio / 100.0;
-  const double maximum_used_percentage = 1.0 - minimum_free_percentage;
-
-  // Compute some numbers about the state of the heap.
-  const size_t used_after_gc = used();
-  const size_t capacity_after_gc = capacity();
-
-  const double min_tmp = used_after_gc / maximum_used_percentage;
-  size_t minimum_desired_capacity = (size_t)MIN2(min_tmp, double(max_uintx));
-  // Don't shrink less than the initial generation size
-  minimum_desired_capacity = MAX2(minimum_desired_capacity,
-                                  spec()->init_size());
-  assert(used_after_gc <= minimum_desired_capacity, "sanity check");
-
-  if (PrintGC && Verbose) {
-    const size_t free_after_gc = free();
-    const double free_percentage = ((double)free_after_gc) / capacity_after_gc;
-    gclog_or_tty->print_cr("TenuredGeneration::compute_new_size: ");
-    gclog_or_tty->print_cr("  "
-                  "  minimum_free_percentage: %6.2f"
-                  "  maximum_used_percentage: %6.2f",
-                  minimum_free_percentage,
-                  maximum_used_percentage);
-    gclog_or_tty->print_cr("  "
-                  "   free_after_gc   : %6.1fK"
-                  "   used_after_gc   : %6.1fK"
-                  "   capacity_after_gc   : %6.1fK",
-                  free_after_gc / (double) K,
-                  used_after_gc / (double) K,
-                  capacity_after_gc / (double) K);
-    gclog_or_tty->print_cr("  "
-                  "   free_percentage: %6.2f",
-                  free_percentage);
-  }
-
-  if (capacity_after_gc < minimum_desired_capacity) {
-    // If we have less free space than we want then expand
-    size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
-    // Don't expand unless it's significant
-    if (expand_bytes >= _min_heap_delta_bytes) {
-      expand(expand_bytes, 0); // safe if expansion fails
-    }
-    if (PrintGC && Verbose) {
-      gclog_or_tty->print_cr("    expanding:"
-                    "  minimum_desired_capacity: %6.1fK"
-                    "  expand_bytes: %6.1fK"
-                    "  _min_heap_delta_bytes: %6.1fK",
-                    minimum_desired_capacity / (double) K,
-                    expand_bytes / (double) K,
-                    _min_heap_delta_bytes / (double) K);
-    }
-    return;
-  }
-
-  // No expansion, now see if we want to shrink
-  size_t shrink_bytes = 0;
-  // We would never want to shrink more than this
-  size_t max_shrink_bytes = capacity_after_gc - minimum_desired_capacity;
-
-  if (MaxHeapFreeRatio < 100) {
-    const double maximum_free_percentage = MaxHeapFreeRatio / 100.0;
-    const double minimum_used_percentage = 1.0 - maximum_free_percentage;
-    const double max_tmp = used_after_gc / minimum_used_percentage;
-    size_t maximum_desired_capacity = (size_t)MIN2(max_tmp, double(max_uintx));
-    maximum_desired_capacity = MAX2(maximum_desired_capacity,
-                                    spec()->init_size());
-    if (PrintGC && Verbose) {
-      gclog_or_tty->print_cr("  "
-                             "  maximum_free_percentage: %6.2f"
-                             "  minimum_used_percentage: %6.2f",
-                             maximum_free_percentage,
-                             minimum_used_percentage);
-      gclog_or_tty->print_cr("  "
-                             "  _capacity_at_prologue: %6.1fK"
-                             "  minimum_desired_capacity: %6.1fK"
-                             "  maximum_desired_capacity: %6.1fK",
-                             _capacity_at_prologue / (double) K,
-                             minimum_desired_capacity / (double) K,
-                             maximum_desired_capacity / (double) K);
-    }
-    assert(minimum_desired_capacity <= maximum_desired_capacity,
-           "sanity check");
-
-    if (capacity_after_gc > maximum_desired_capacity) {
-      // Capacity too large, compute shrinking size
-      shrink_bytes = capacity_after_gc - maximum_desired_capacity;
-      // We don't want shrink all the way back to initSize if people call
-      // System.gc(), because some programs do that between "phases" and then
-      // we'd just have to grow the heap up again for the next phase.  So we
-      // damp the shrinking: 0% on the first call, 10% on the second call, 40%
-      // on the third call, and 100% by the fourth call.  But if we recompute
-      // size without shrinking, it goes back to 0%.
-      shrink_bytes = shrink_bytes / 100 * current_shrink_factor;
-      assert(shrink_bytes <= max_shrink_bytes, "invalid shrink size");
-      if (current_shrink_factor == 0) {
-        _shrink_factor = 10;
-      } else {
-        _shrink_factor = MIN2(current_shrink_factor * 4, (size_t) 100);
-      }
-      if (PrintGC && Verbose) {
-        gclog_or_tty->print_cr("  "
-                      "  shrinking:"
-                      "  initSize: %.1fK"
-                      "  maximum_desired_capacity: %.1fK",
-                      spec()->init_size() / (double) K,
-                      maximum_desired_capacity / (double) K);
-        gclog_or_tty->print_cr("  "
-                      "  shrink_bytes: %.1fK"
-                      "  current_shrink_factor: %d"
-                      "  new shrink factor: %d"
-                      "  _min_heap_delta_bytes: %.1fK",
-                      shrink_bytes / (double) K,
-                      current_shrink_factor,
-                      _shrink_factor,
-                      _min_heap_delta_bytes / (double) K);
-      }
-    }
-  }
-
-  if (capacity_after_gc > _capacity_at_prologue) {
-    // We might have expanded for promotions, in which case we might want to
-    // take back that expansion if there's room after GC.  That keeps us from
-    // stretching the heap with promotions when there's plenty of room.
-    size_t expansion_for_promotion = capacity_after_gc - _capacity_at_prologue;
-    expansion_for_promotion = MIN2(expansion_for_promotion, max_shrink_bytes);
-    // We have two shrinking computations, take the largest
-    shrink_bytes = MAX2(shrink_bytes, expansion_for_promotion);
-    assert(shrink_bytes <= max_shrink_bytes, "invalid shrink size");
-    if (PrintGC && Verbose) {
-      gclog_or_tty->print_cr("  "
-                             "  aggressive shrinking:"
-                             "  _capacity_at_prologue: %.1fK"
-                             "  capacity_after_gc: %.1fK"
-                             "  expansion_for_promotion: %.1fK"
-                             "  shrink_bytes: %.1fK",
-                             capacity_after_gc / (double) K,
-                             _capacity_at_prologue / (double) K,
-                             expansion_for_promotion / (double) K,
-                             shrink_bytes / (double) K);
-    }
-  }
-  // Don't shrink unless it's significant
-  if (shrink_bytes >= _min_heap_delta_bytes) {
-    shrink(shrink_bytes);
-  }
-  assert(used() == used_after_gc && used_after_gc <= capacity(),
-         "sanity check");
-}
-
 void TenuredGeneration::gc_prologue(bool full) {
   _capacity_at_prologue = capacity();
   _used_at_prologue = used();
@@ -312,6 +156,19 @@ void TenuredGeneration::collect(bool   full,
                                         size, is_tlab);
 }
 
+void TenuredGeneration::compute_new_size() {
+  assert_locked_or_safepoint(Heap_lock);
+
+  // Compute some numbers about the state of the heap.
+  const size_t used_after_gc = used();
+  const size_t capacity_after_gc = capacity();
+
+  CardGeneration::compute_new_size();
+
+  assert(used() == used_after_gc && used_after_gc <= capacity(),
+         err_msg("used: " SIZE_FORMAT " used_after_gc: " SIZE_FORMAT
+         " capacity: " SIZE_FORMAT, used(), used_after_gc, capacity()));
+}
 void TenuredGeneration::update_gc_stats(int current_level,
                                         bool full) {
   // If the next lower level(s) has been collected, gather any statistics

hotspot/src/share/vm/memory/tenuredGeneration.hpp

@@ -38,13 +38,6 @@ class ParGCAllocBufferWithBOT;
 class TenuredGeneration: public OneContigSpaceCardGeneration {
   friend class VMStructs;
  protected:
-  // current shrinking effect: this damps shrinking when the heap gets empty.
-  size_t _shrink_factor;
-  // Some statistics from before gc started.
-  // These are gathered in the gc_prologue (and should_collect)
-  // to control growing/shrinking policy in spite of promotions.
-  size_t _capacity_at_prologue;
-  size_t _used_at_prologue;
 
 #if INCLUDE_ALL_GCS
   // To support parallel promotion: an array of parallel allocation
@@ -80,9 +73,6 @@ class TenuredGeneration: public OneContigSpaceCardGeneration {
     return !CollectGen0First;
   }
 
-  // Mark sweep support
-  void compute_new_size();
-
   virtual void gc_prologue(bool full);
   virtual void gc_epilogue(bool full);
   bool should_collect(bool   full,
@@ -93,6 +83,7 @@ class TenuredGeneration: public OneContigSpaceCardGeneration {
                        bool clear_all_soft_refs,
                        size_t size,
                        bool is_tlab);
+  virtual void compute_new_size();
 
 #if INCLUDE_ALL_GCS
   // Overrides.

hotspot/src/share/vm/runtime/vmStructs.cpp

@@ -478,6 +478,9 @@ typedef BinaryTreeDictionary<Metablock, FreeList> MetablockTreeDictionary;
                                                                                                                                      \
   nonstatic_field(CardGeneration,              _rs,                                           GenRemSet*)                            \
   nonstatic_field(CardGeneration,              _bts,                                          BlockOffsetSharedArray*)               \
+  nonstatic_field(CardGeneration,              _shrink_factor,                                size_t)                                \
+  nonstatic_field(CardGeneration,              _capacity_at_prologue,                         size_t)                                \
+  nonstatic_field(CardGeneration,              _used_at_prologue,                             size_t)                                \
                                                                                                                                      \
   nonstatic_field(CardTableModRefBS,           _whole_heap,                                   const MemRegion)                       \
   nonstatic_field(CardTableModRefBS,           _guard_index,                                  const size_t)                          \
@@ -548,8 +551,6 @@ typedef BinaryTreeDictionary<Metablock, FreeList> MetablockTreeDictionary;
   nonstatic_field(Space,                       _bottom,                                       HeapWord*)                             \
   nonstatic_field(Space,                       _end,                                          HeapWord*)                             \
                                                                                                                                      \
-  nonstatic_field(TenuredGeneration,           _shrink_factor,                                size_t)                                \
-  nonstatic_field(TenuredGeneration,           _capacity_at_prologue,                         size_t)                                \
   nonstatic_field(ThreadLocalAllocBuffer,      _start,                                        HeapWord*)                             \
   nonstatic_field(ThreadLocalAllocBuffer,      _top,                                          HeapWord*)                             \
   nonstatic_field(ThreadLocalAllocBuffer,      _end,                                          HeapWord*)                             \