Reduce GC from external allocation.

runtime/vm/heap.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/heap.h"
 
 #include "platform/assert.h"
 #include "platform/utils.h"
 #include "vm/flags.h"
 #include "vm/isolate.h"
@@ skipping 16 matching lines @@
 DEFINE_FLAG(bool, verify_before_gc, false,
             "Enables heap verification before GC.");
 DEFINE_FLAG(bool, verify_after_gc, false,
             "Enables heap verification after GC.");
 DEFINE_FLAG(bool, gc_at_alloc, false, "GC at every allocation.");
 DEFINE_FLAG(int, new_gen_heap_size, 32, "new gen heap size in MB,"
             "e.g: --new_gen_heap_size=64 allocates a 64MB new gen heap");
 DEFINE_FLAG(int, old_gen_heap_size, Heap::kHeapSizeInMB,
             "old gen heap size in MB,"
             "e.g: --old_gen_heap_size=1024 allocates a 1024MB old gen heap");
+DEFINE_FLAG(int, new_gen_ext_limit, 64,
+            "maximum total external size (MB) in new gen before triggering GC");
 
 Heap::Heap() : read_only_(false), gc_in_progress_(false) {
   for (int sel = 0;
        sel < kNumWeakSelectors;
        sel++) {
     new_weak_tables_[sel] = new WeakTable();
     old_weak_tables_[sel] = new WeakTable();
   }
   new_space_ = new Scavenger(this,
                              (FLAG_new_gen_heap_size * MBInWords),
@@ skipping 40 matching lines @@
                    size);
       return 0;
     }
   }
   return addr;
 }
 
 void Heap::AllocateExternal(intptr_t size, Space space) {
   if (space == kNew) {
     new_space_->AllocateExternal(size);
+    if (new_space_->ExternalInWords() > (FLAG_new_gen_ext_limit * MBInWords)) {
+      // Attempt to free some external allocation by a scavenge. (If the total
+      // remains above the limit, next external alloc will trigger another.)
+      CollectGarbage(kNew);
+    }
   } else {
     ASSERT(space == kOld);
     old_space_->AllocateExternal(size);
   }
 }
 
 void Heap::FreeExternal(intptr_t size, Space space) {
   if (space == kNew) {
     new_space_->FreeExternal(size);
   } else {
@@ skipping 465 matching lines @@
     heap->DisableGrowthControl();
 }
 
 
 NoHeapGrowthControlScope::~NoHeapGrowthControlScope() {
     Heap* heap = reinterpret_cast<Isolate*>(isolate())->heap();
     heap->SetGrowthControlState(current_growth_controller_state_);
 }
 
 }  // namespace dart