src: free placeholder nodes for cppgc wrappers in MemoryTracker

src/memory_tracker-inl.h

@@ -300,7 +300,7 @@ void MemoryTracker::Track(const CppgcMixin* retainer, const char* edge_name) {
  auto it = seen_.find(retainer);
  if (it != seen_.end()) {
  if (CurrentNode() != nullptr) {
- AddEdge(CurrentNode(), it->second, edge_name);
+ AddEdge(CurrentNode(), it->second->JSWrapperNode(), edge_name);
  }
  return; // It has already been tracked, no need to call MemoryInfo again
  }
@@ -357,6 +357,11 @@ inline void MemoryTracker::TraitTrackInline(const T& retainer,
  -(static_cast<int>(MemoryRetainerTraits<T>::SelfSize(retainer))));
 }
 
+MemoryTracker::MemoryTracker(v8::Isolate* isolate, v8::EmbedderGraph* graph)
+ : isolate_(isolate), graph_(graph) {}
+
+MemoryTracker::~MemoryTracker() = default;
+
 v8::EmbedderGraph::Node* MemoryTracker::CurrentNode() const {
  if (node_stack_.empty()) return nullptr;
  MemoryRetainerNode* n = node_stack_.top();
@@ -373,7 +378,8 @@ MemoryRetainerNode* MemoryTracker::AddNode(const CppgcMixin* retainer,
  return it->second;
  }
 
- MemoryRetainerNode* n = new MemoryRetainerNode(this, retainer);
+ cppgc_nodes_.push_back(std::make_unique<MemoryRetainerNode>(this, retainer));
+ MemoryRetainerNode* n = cppgc_nodes_.back().get();
  seen_[retainer] = n;
  if (CurrentNode() != nullptr) {
  AddEdge(CurrentNode(), n->JSWrapperNode(), edge_name);

src/memory_tracker.h

@@ -8,10 +8,12 @@
 #include <uv.h>
 
 #include <limits>
+#include <memory>
 #include <queue>
 #include <stack>
 #include <string>
 #include <unordered_map>
+#include <vector>
 
 namespace v8 {
 class BackingStore;
@@ -294,9 +296,8 @@ class MemoryTracker {
  inline v8::EmbedderGraph* graph() { return graph_; }
  inline v8::Isolate* isolate() { return isolate_; }
 
- inline explicit MemoryTracker(v8::Isolate* isolate,
- v8::EmbedderGraph* graph)
- : isolate_(isolate), graph_(graph) {}
+ inline explicit MemoryTracker(v8::Isolate* isolate, v8::EmbedderGraph* graph);
+ inline ~MemoryTracker();
 
  // Can be passed to Track() if it is not desirable
  // to create a strong edge between nodes, i.e. when
@@ -334,6 +335,8 @@ class MemoryTracker {
  v8::EmbedderGraph* graph_;
  std::stack<MemoryRetainerNode*> node_stack_;
  NodeMap seen_;
+ // Placeholder nodes for cppgc wrappers; the graph only owns their JS nodes.
+ std::vector<std::unique_ptr<MemoryRetainerNode>> cppgc_nodes_;
 };
 
 } // namespace node

test/cctest/test_environment.cc

@@ -328,6 +328,19 @@ TEST_F(EnvironmentTest, MultipleEnvironmentsPerIsolate) {
  EXPECT_TRUE(called_cb_2);
 }
 
+TEST_F(EnvironmentTest, HeapSnapshotWithCppgcWrappersDoesNotLeak) {
+ const v8::HandleScope handle_scope(isolate_);
+ const Argv argv;
+ Env env{handle_scope, argv};
+ node::LoadEnvironment(*env,
+ "const vm = require('vm');"
+ "globalThis.script = new vm.Script('1');"
+ "globalThis.context = vm.createContext();")
+ .ToLocalChecked();
+ node::heap::HeapSnapshotPointer snapshot{
+ isolate_->GetHeapProfiler()->TakeHeapSnapshot()};
+}
+
 TEST_F(EnvironmentTest, NoEnvironmentSanity) {
  const v8::HandleScope handle_scope(isolate_);
  v8::Local<v8::Context> context = v8::Context::New(isolate_);