[GC] Change behavior when reaching external allocation limit

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index 586fd8613a5a4b9dcaa5b47bfa4d56e65d804c7b..53921f5bed20386235ada0403d8230e47e2e6282 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -6884,8 +6884,20 @@ Local<Integer> v8::Integer::NewFromUnsigned(Isolate* isolate, uint32_t value) {
 
 
 void Isolate::CollectAllGarbage(const char* gc_reason) {
-  reinterpret_cast<i::Isolate*>(this)->heap()->CollectAllGarbage(
-      i::Heap::kNoGCFlags, gc_reason, v8::kGCCallbackFlagForced);
+  using IM = i::IncrementalMarking;
+  using Heap = i::Heap;

[jochen (gone - plz use gerrit), 2015/08/05 12:22:27]

please don't use using.

[Michael Lippautz, 2015/08/05 12:55:58]

Done.

+  double kIncrementalMarkingIntervalInMs = 3;

[Michael Lippautz, 2015/08/05 12:08:26]

keep local?

[jochen (gone - plz use gerrit), 2015/08/05 12:22:27]

maybe make it a flag?

[Hannes Payer (out of office), 2015/08/05 12:39:36]

I would prefer 1 instead of 3. The smaller the better.

It would be nice to calculate the value, based on memory pressure. More ms for
higher memory pressure. That could be a TODO.

[Michael Lippautz, 2015/08/05 12:55:58]

1ms it is. Works on N9. 

Agree that it would be better to dynamically adjust the 
time slices.

[Michael Lippautz, 2015/08/05 12:55:58]

Done.

+
+  Heap* heap = reinterpret_cast<i::Isolate*>(this)->heap();
+  if (heap->incremental_marking()->IsStopped()) {
+    heap->StartIncrementalMarking(Heap::kNoGCFlags, kGCCallbackFlagForced,
+                                  gc_reason);
+  }
+  double deadline =
+      heap->MonotonicallyIncreasingTimeInMs() + kIncrementalMarkingIntervalInMs;
+  heap->AdvanceIncrementalMarking(
+      0, deadline, IM::StepActions(IM::GC_VIA_STACK_GUARD, IM::FORCE_MARKING,
+                                   IM::FORCE_COMPLETION));
 }