Grow heap slower if GC freed many global handles.

src/heap.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/base/once.h"
 #include "src/bootstrapper.h"
@@ skipping 43 matching lines @@
       reserved_semispace_size_(8 * (kPointerSize / 4) * MB),
       max_semi_space_size_(8 * (kPointerSize / 4)  * MB),
       initial_semispace_size_(Page::kPageSize),
       max_old_generation_size_(700ul * (kPointerSize / 4) * MB),
       max_executable_size_(256ul * (kPointerSize / 4) * MB),
 // Variables set based on semispace_size_ and old_generation_size_ in
 // ConfigureHeap.
 // Will be 4 * reserved_semispace_size_ to ensure that young
 // generation can be aligned to its size.
       maximum_committed_(0),
-      old_space_growing_factor_(4),
       survived_since_last_expansion_(0),
       sweep_generation_(0),
       always_allocate_scope_depth_(0),
       contexts_disposed_(0),
       global_ic_age_(0),
       flush_monomorphic_ics_(false),
       scan_on_scavenge_pages_(0),
       new_space_(this),
       old_pointer_space_(NULL),
       old_data_space_(NULL),
       code_space_(NULL),
       map_space_(NULL),
       cell_space_(NULL),
       property_cell_space_(NULL),
       lo_space_(NULL),
       gc_state_(NOT_IN_GC),
       gc_post_processing_depth_(0),
       allocations_count_(0),
       raw_allocations_hash_(0),
       dump_allocations_hash_countdown_(FLAG_dump_allocations_digest_at_alloc),
       ms_count_(0),
       gc_count_(0),
       remembered_unmapped_pages_index_(0),
       unflattened_strings_length_(0),
 #ifdef DEBUG
       allocation_timeout_(0),
 #endif  // DEBUG
       old_generation_allocation_limit_(kMinimumOldGenerationAllocationLimit),
-      size_of_old_gen_at_last_old_space_gc_(0),
       old_gen_exhausted_(false),
       inline_allocation_disabled_(false),
       store_buffer_rebuilder_(store_buffer()),
       hidden_string_(NULL),
       gc_safe_size_of_old_object_(NULL),
       total_regexp_code_generated_(0),
       tracer_(NULL),
       high_survival_rate_period_length_(0),
       promoted_objects_size_(0),
       promotion_rate_(0),
@@ skipping 945 matching lines @@
     high_survival_rate_period_length_++;
   } else {
     high_survival_rate_period_length_ = 0;
   }
 }
 
 bool Heap::PerformGarbageCollection(
     GarbageCollector collector,
     GCTracer* tracer,
     const v8::GCCallbackFlags gc_callback_flags) {
-  bool next_gc_likely_to_collect_more = false;
+  int freed_global_handles = 0;
 
   if (collector != SCAVENGER) {
     PROFILE(isolate_, CodeMovingGCEvent());
   }
 
 #ifdef VERIFY_HEAP
   if (FLAG_verify_heap) {
     VerifyStringTable(this);
   }
 #endif
@@ skipping 19 matching lines @@
     // We speed up the incremental marker if it is running so that it
     // does not fall behind the rate of promotion, which would cause a
     // constantly growing old space.
     incremental_marking()->NotifyOfHighPromotionRate();
   }
 
   if (collector == MARK_COMPACTOR) {
     // Perform mark-sweep with optional compaction.
     MarkCompact(tracer);
     sweep_generation_++;
-
-    size_of_old_gen_at_last_old_space_gc_ = PromotedSpaceSizeOfObjects();
-
+    // Temporarily set the limit for case when PostGarbageCollectionProcessing
+    // allocates and triggers GC. The real limit is set at after
+    // PostGarbageCollectionProcessing.
     old_generation_allocation_limit_ =
-        OldGenerationAllocationLimit(size_of_old_gen_at_last_old_space_gc_);
-
+        OldGenerationAllocationLimit(PromotedSpaceSizeOfObjects(), 0);
     old_gen_exhausted_ = false;
   } else {
     tracer_ = tracer;
     Scavenge();
     tracer_ = NULL;
   }
 
   UpdateSurvivalStatistics(start_new_space_size);
 
   isolate_->counters()->objs_since_last_young()->Set(0);
 
   // Callbacks that fire after this point might trigger nested GCs and
   // restart incremental marking, the assertion can't be moved down.
   ASSERT(collector == SCAVENGER || incremental_marking()->IsStopped());
 
   gc_post_processing_depth_++;
   { AllowHeapAllocation allow_allocation;
     GCTracer::Scope scope(tracer, GCTracer::Scope::EXTERNAL);
-    next_gc_likely_to_collect_more =
+    freed_global_handles =
         isolate_->global_handles()->PostGarbageCollectionProcessing(
             collector, tracer);
   }
   gc_post_processing_depth_--;
 
   isolate_->eternal_handles()->PostGarbageCollectionProcessing(this);
 
   // Update relocatables.
   Relocatable::PostGarbageCollectionProcessing(isolate_);
 
   if (collector == MARK_COMPACTOR) {
     // Register the amount of external allocated memory.
     amount_of_external_allocated_memory_at_last_global_gc_ =
         amount_of_external_allocated_memory_;
+    old_generation_allocation_limit_ =
+        OldGenerationAllocationLimit(PromotedSpaceSizeOfObjects(),
+                                     freed_global_handles);
   }
 
   { GCCallbacksScope scope(this);
     if (scope.CheckReenter()) {
       AllowHeapAllocation allow_allocation;
       GCTracer::Scope scope(tracer, GCTracer::Scope::EXTERNAL);
       VMState<EXTERNAL> state(isolate_);
       HandleScope handle_scope(isolate_);
       CallGCEpilogueCallbacks(gc_type, gc_callback_flags);
     }
   }
 
 #ifdef VERIFY_HEAP
   if (FLAG_verify_heap) {
     VerifyStringTable(this);
   }
 #endif
 
-  return next_gc_likely_to_collect_more;
+  return freed_global_handles > 0;
 }
 
 
 void Heap::CallGCPrologueCallbacks(GCType gc_type, GCCallbackFlags flags) {
   for (int i = 0; i < gc_prologue_callbacks_.length(); ++i) {
     if (gc_type & gc_prologue_callbacks_[i].gc_type) {
       if (!gc_prologue_callbacks_[i].pass_isolate_) {
         v8::GCPrologueCallback callback =
             reinterpret_cast<v8::GCPrologueCallback>(
                 gc_prologue_callbacks_[i].callback);
@@ skipping 3785 matching lines @@
           max_old_generation_size_);
 
   // We rely on being able to allocate new arrays in paged spaces.
   ASSERT(Page::kMaxRegularHeapObjectSize >=
          (JSArray::kSize +
           FixedArray::SizeFor(JSObject::kInitialMaxFastElementArray) +
           AllocationMemento::kSize));
 
   code_range_size_ = code_range_size * MB;
 
-  // We set the old generation growing factor to 2 to grow the heap slower on
-  // memory-constrained devices.
-  if (max_old_generation_size_ <= kMaxOldSpaceSizeMediumMemoryDevice) {
-    old_space_growing_factor_ = 2;
-  }
-
   configured_ = true;
   return true;
 }
 
 
 bool Heap::ConfigureHeapDefault() {
   return ConfigureHeap(0, 0, 0, 0);
 }
 
 
@@ skipping 48 matching lines @@
 
 
 int64_t Heap::PromotedExternalMemorySize() {
   if (amount_of_external_allocated_memory_
       <= amount_of_external_allocated_memory_at_last_global_gc_) return 0;
   return amount_of_external_allocated_memory_
       - amount_of_external_allocated_memory_at_last_global_gc_;
 }
 
 
+intptr_t Heap::OldGenerationAllocationLimit(intptr_t old_gen_size,
+                                            int freed_global_handles) {
+  const int kMaxHandles = 1000;
+  const int kMinHandles = 100;
+  double min_factor = 1.1;
+  double max_factor = 4;
+  // We set the old generation growing factor to 2 to grow the heap slower on
+  // memory-constrained devices.
+  if (max_old_generation_size_ <= kMaxOldSpaceSizeMediumMemoryDevice) {
+    max_factor = 2;
+  }
+  // If there are many freed global handles, then the next full GC will
+  // likely collect a lot of garbage. Choose the heap growing factor
+  // depending on freed global handles.
+  // TODO(ulan, hpayer): Take into account mutator utilization.
+  double factor;
+  if (freed_global_handles <= kMinHandles) {
+    factor = max_factor;
+  } else if (freed_global_handles >= kMaxHandles) {
+    factor = min_factor;
+  } else {
+    factor = max_factor -

[Hannes Payer (out of office), 2014/06/25 09:24:00]

Could you please leave a comment here that explains what that function does?

+             (freed_global_handles - kMinHandles) * (max_factor - min_factor) /
+             (kMaxHandles - kMinHandles);
+  }
+
+  if (FLAG_stress_compaction ||
+      mark_compact_collector()->reduce_memory_footprint_) {
+    factor = min_factor;
+  }
+
+  intptr_t limit = static_cast<intptr_t>(old_gen_size * factor);
+  limit = Max(limit, kMinimumOldGenerationAllocationLimit);
+  limit += new_space_.Capacity();
+  intptr_t halfway_to_the_max = (old_gen_size + max_old_generation_size_) / 2;
+  return Min(limit, halfway_to_the_max);
+}
+
+
 void Heap::EnableInlineAllocation() {
   if (!inline_allocation_disabled_) return;
   inline_allocation_disabled_ = false;
 
   // Update inline allocation limit for new space.
   new_space()->UpdateInlineAllocationLimit(0);
 }
 
 
 void Heap::DisableInlineAllocation() {
@@ skipping 1324 matching lines @@
       static_cast<int>(object_sizes_last_time_[index]));
   CODE_AGE_LIST_COMPLETE(ADJUST_LAST_TIME_OBJECT_COUNT)
 #undef ADJUST_LAST_TIME_OBJECT_COUNT
 
   MemCopy(object_counts_last_time_, object_counts_, sizeof(object_counts_));
   MemCopy(object_sizes_last_time_, object_sizes_, sizeof(object_sizes_));
   ClearObjectStats();
 }
 
 } }  // namespace v8::internal