nodejs
diff --git a/‎src/node_file-inl.h‎
Lines changed: 21 additions & 13 deletions b/‎src/node_file-inl.h‎
Lines changed: 21 additions & 13 deletions
diff --git a/‎src/node_file.h‎
Lines changed: 5 additions & 2 deletions b/‎src/node_file.h‎
Lines changed: 5 additions & 2 deletions
diff --git a/‎test/pummel/test-heapdump-fs-promise.js‎
Lines changed: 3 additions & 3 deletions b/‎test/pummel/test-heapdump-fs-promise.js‎
Lines changed: 3 additions & 3 deletions
@@ -209,13 +209,7 @@ FSReqPromise<AliasedBufferT>::FSReqPromise(BindingData* binding_data,
                                            v8::Local<v8::Object> obj,
                                            bool use_bigint)
     : FSReqBase(
-          binding_data, obj, AsyncWrap::PROVIDER_FSREQPROMISE, use_bigint),
-      stats_field_array_(
-          env()->isolate(),
-          static_cast<size_t>(FsStatsOffset::kFsStatsFieldsNumber)),
-      statfs_field_array_(
-          env()->isolate(),
-          static_cast<size_t>(FsStatFsOffset::kFsStatFsFieldsNumber)) {}
+          binding_data, obj, AsyncWrap::PROVIDER_FSREQPROMISE, use_bigint) {}
 
 template <typename AliasedBufferT>
 void FSReqPromise<AliasedBufferT>::Reject(v8::Local<v8::Value> reject) {
@@ -253,14 +247,24 @@ void FSReqPromise<AliasedBufferT>::Resolve(v8::Local<v8::Value> value) {
 
 template <typename AliasedBufferT>
 void FSReqPromise<AliasedBufferT>::ResolveStat(const uv_stat_t* stat) {
-  FillStatsArray(&stats_field_array_, stat);
-  Resolve(stats_field_array_.GetJSArray());
+  if (!stats_field_array_.has_value()) {
+    stats_field_array_.emplace(
+        env()->isolate(),
+        static_cast<size_t>(FsStatsOffset::kFsStatsFieldsNumber));
+  }
+  FillStatsArray(&stats_field_array_.value(), stat);
+  Resolve(stats_field_array_->GetJSArray());
 }
 
 template <typename AliasedBufferT>
 void FSReqPromise<AliasedBufferT>::ResolveStatFs(const uv_statfs_t* stat) {
-  FillStatFsArray(&statfs_field_array_, stat);
-  Resolve(statfs_field_array_.GetJSArray());
+  if (!statfs_field_array_.has_value()) {
+    statfs_field_array_.emplace(
+        env()->isolate(),
+        static_cast<size_t>(FsStatFsOffset::kFsStatFsFieldsNumber));
+  }
+  FillStatFsArray(&statfs_field_array_.value(), stat);
+  Resolve(statfs_field_array_->GetJSArray());
 }
 
 template <typename AliasedBufferT>
@@ -280,8 +284,12 @@ void FSReqPromise<AliasedBufferT>::SetReturnValue(
 template <typename AliasedBufferT>
 void FSReqPromise<AliasedBufferT>::MemoryInfo(MemoryTracker* tracker) const {
   FSReqBase::MemoryInfo(tracker);
-  tracker->TrackField("stats_field_array", stats_field_array_);
-  tracker->TrackField("statfs_field_array", statfs_field_array_);
+  if (stats_field_array_.has_value()) {
+    tracker->TrackField("stats_field_array", stats_field_array_.value());
+  }
+  if (statfs_field_array_.has_value()) {
+    tracker->TrackField("statfs_field_array", statfs_field_array_.value());
+  }
 }
 
 FSReqBase* GetReqWrap(const v8::FunctionCallbackInfo<v8::Value>& args,
 
@@ -266,8 +266,11 @@ class FSReqPromise final : public FSReqBase {
                       bool use_bigint);
 
   bool finished_ = false;
-  AliasedBufferT stats_field_array_;
-  AliasedBufferT statfs_field_array_;
+  // Constructed lazily in ResolveStat()/ResolveStatFs(): most operations
+  // never resolve with stats, and eagerly allocating the backing stores
+  // for every request is a significant per-request cost.
+  std::optional<AliasedBufferT> stats_field_array_;
+  std::optional<AliasedBufferT> statfs_field_array_;
 };
 
 class FSReqAfterScope final {
 
@@ -20,7 +20,7 @@ fs.stat(__filename);
   validateByRetainingPathFromNodes(nodes, 'Node / FSReqPromise', [
     { node_name: 'FSReqPromise', edge_name: 'native_to_javascript' },
   ]);
-  validateByRetainingPathFromNodes(nodes, 'Node / FSReqPromise', [
-    { node_name: 'Node / AliasedFloat64Array', edge_name: 'stats_field_array' },
-  ]);
+  // The stats field array is allocated lazily when the request resolves
+  // with stats, so it is not retained by a request that is still pending
+  // and cannot be observed in a heap snapshot.
 }