A temporary workaround for huge heap snapshots problem.

src/profile-generator.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1177 matching lines @@
 void HeapSnapshot::Delete() {
   collection_->RemoveSnapshot(this);
   delete this;
 }
 
 
 void HeapSnapshot::AllocateEntries(int entries_count,
                                    int children_count,
                                    int retainers_count) {
   ASSERT(raw_entries_ == NULL);
-  raw_entries_ = NewArray<char>(
-      HeapEntry::EntriesSize(entries_count, children_count, retainers_count));
-#ifdef DEBUG
   raw_entries_size_ =
       HeapEntry::EntriesSize(entries_count, children_count, retainers_count);
-#endif
+  raw_entries_ = NewArray<char>(raw_entries_size_);
 }
 
 
 static void HeapEntryClearPaint(HeapEntry** entry_ptr) {
   (*entry_ptr)->clear_paint();
 }
 
 void HeapSnapshot::ClearPaint() {
   entries_.Iterate(HeapEntryClearPaint);
 }
@@ skipping 1763 matching lines @@
         v8::OutputStream::kAbort) aborted_ = true;
   }
 
   v8::OutputStream* stream_;
   int chunk_size_;
   ScopedVector<char> chunk_;
   int chunk_pos_;
   bool aborted_;
 };
 
+const int HeapSnapshotJSONSerializer::kMaxSerializableSnapshotRawSize =
+    384 * 1024;

[William Hesse, 2011/09/05 07:31:00]

We have constants KB, MB, and GB defined in globals.h for the binary orders of
magnitude.  I would use KB instead of 1024.

[mnaganov (inactive), 2011/09/05 07:33:10]

Thanks! I forgot about that, will fix before landing.

+
 void HeapSnapshotJSONSerializer::Serialize(v8::OutputStream* stream) {
   ASSERT(writer_ == NULL);
   writer_ = new OutputStreamWriter(stream);
 
+  HeapSnapshot* original_snapshot = NULL;
+  if (snapshot_->raw_entries_size() >= kMaxSerializableSnapshotRawSize) {
+    // The snapshot is too big. Serialize a fake snapshot.
+    original_snapshot = snapshot_;
+    snapshot_ = CreateFakeSnapshot();
+  }
   // Since nodes graph is cyclic, we need the first pass to enumerate
   // them. Strings can be serialized in one pass.
   EnumerateNodes();
   SerializeImpl();
 
   delete writer_;
   writer_ = NULL;
+
+  if (original_snapshot != NULL) {
+    delete snapshot_;
+    snapshot_ = original_snapshot;
+  }
 }
 
 
+HeapSnapshot* HeapSnapshotJSONSerializer::CreateFakeSnapshot() {
+  HeapSnapshot* result = new HeapSnapshot(snapshot_->collection(),
+                                          HeapSnapshot::kFull,
+                                          snapshot_->title(),
+                                          snapshot_->uid());
+  result->AllocateEntries(2, 1, 0);
+  HeapEntry* root = result->AddRootEntry(1);
+  HeapEntry* message = result->AddEntry(
+      HeapEntry::kString, "The snapshot is too big", 0, 4, 0, 0);
+  root->SetUnidirElementReference(0, 1, message);
+  result->SetDominatorsToSelf();
+  return result;
+}
+
+
 void HeapSnapshotJSONSerializer::SerializeImpl() {
   writer_->AddCharacter('{');
   writer_->AddString("\"snapshot\":{");
   SerializeSnapshot();
   if (writer_->aborted()) return;
   writer_->AddString("},\n");
   writer_->AddString("\"nodes\":[");
   SerializeNodes();
   if (writer_->aborted()) return;
   writer_->AddString("],\n");
@@ skipping 257 matching lines @@
 
 
 void HeapSnapshotJSONSerializer::SortHashMap(
     HashMap* map, List<HashMap::Entry*>* sorted_entries) {
   for (HashMap::Entry* p = map->Start(); p != NULL; p = map->Next(p))
     sorted_entries->Add(p);
   sorted_entries->Sort(SortUsingEntryValue);
 }
 
 } }  // namespace v8::internal