Sampling heap profiler: remove empty nodes from profile.

src/profiler/sampling-heap-profiler.cc

Index: src/profiler/sampling-heap-profiler.cc
diff --git a/src/profiler/sampling-heap-profiler.cc b/src/profiler/sampling-heap-profiler.cc
index 942562dca18c16d0f6322497664a163b6c1f2b3b..337a9af90a802ddbe7f4449e67147894f9600157 100644
--- a/src/profiler/sampling-heap-profiler.cc
+++ b/src/profiler/sampling-heap-profiler.cc
@@ -58,7 +58,7 @@ SamplingHeapProfiler::SamplingHeapProfiler(Heap* heap, StringsStorage* names,
           heap_, static_cast<intptr_t>(rate), rate, this,
           heap->isolate()->random_number_generator())),
       names_(names),
-      profile_root_("(root)", v8::UnboundScript::kNoScriptId, 0),
+      profile_root_(NULL, "(root)", v8::UnboundScript::kNoScriptId, 0),

[ulan, 2016/04/28 09:11:57]

nullptr

[alph, 2016/04/28 22:14:39]

Thanks. Fixed other places as well.

       samples_(),
       stack_depth_(stack_depth),
       rate_(rate) {
@@ -119,6 +119,14 @@ void SamplingHeapProfiler::OnWeakCallback(
   node->allocations_[sample->size]--;
   if (node->allocations_[sample->size] == 0) {
     node->allocations_.erase(sample->size);
+    while (node->allocations_.empty() && node->children_.empty() &&
+           node->parent_ && !node->parent_->pinned_) {
+      AllocationNode* parent = node->parent_;
+      parent->children_.erase(
+          std::find(parent->children_.begin(), parent->children_.end(), node));
+      delete node;
+      node = parent;
+    }
   }
   sample->profiler->samples_.erase(sample);
   delete sample;
@@ -134,7 +142,8 @@ SamplingHeapProfiler::AllocationNode* SamplingHeapProfiler::FindOrAddChildNode(
       return child;
     }
   }
-  AllocationNode* child = new AllocationNode(name, script_id, start_position);
+  AllocationNode* child =
+      new AllocationNode(parent, name, script_id, start_position);
   parent->children_.push_back(child);
   return child;
 }
@@ -197,6 +206,9 @@ SamplingHeapProfiler::AllocationNode* SamplingHeapProfiler::AddStack() {
 v8::AllocationProfile::Node* SamplingHeapProfiler::TranslateAllocationNode(
     AllocationProfile* profile, SamplingHeapProfiler::AllocationNode* node,
     const std::map<int, Script*>& scripts) {
+  // By pinning the node we make sure its children won't get disposed if
+  // a GC kicks in during the tree retrieval.
+  node->pinned_ = true;
   Local<v8::String> script_name =
       ToApiHandle<v8::String>(isolate_->factory()->InternalizeUtf8String(""));
   int line = v8::AllocationProfile::kNoLineNumberInfo;
@@ -240,6 +252,7 @@ v8::AllocationProfile::Node* SamplingHeapProfiler::TranslateAllocationNode(
     current->children.push_back(
         TranslateAllocationNode(profile, node->children_[i], scripts));
   }
+  node->pinned_ = false;
   return current;
 }