src: stop leaking a CppHeap in CommonEnvironmentSetup - #65792
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`CommonEnvironmentSetup` created a `CppHeap` for its `CreateParams` before deciding how to create the isolate, but `NewIsolate()` ignores `params->cpp_heap` and attaches a heap of its own (or the one from `IsolateSettings`). The first heap was never attached or destroyed, so every non-snapshotting setup leaked one `CppHeap`; cppgc's heap registry keeps it reachable, which is why LSAN stays quiet about it. Only create the heap on the snapshotting path, where the params go to the `SnapshotCreator` directly. Refs: nodejs#55337 Signed-off-by: Shelley Vohr <[email protected]>
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Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## main #65792 +/- ##
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+ Coverage 89.99% 90.15% +0.15%
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Files 757 769 +12
Lines 257739 261448 +3709
Branches 48881 49661 +780
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+ Hits 231961 235715 +3754
+ Misses 16861 16749 -112
- Partials 8917 8984 +67
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jasnell
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Sep 4, 2026
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CommonEnvironmentSetup's constructor created av8::CppHeapfor itsIsolate::CreateParamsup front, but on the non-snapshotting path it then callsNewIsolate(), which ignoresparams->cpp_heapand attaches either the heap fromIsolateSettingsor a fresh one. The heap created first was never attached to an isolate and never destroyed, so everyCommonEnvironmentSetup::Create()/CreateFromSnapshot()leaked oneCppHeap. cppgc's process-wide heap registry keeps a pointer to it, which is why LeakSanitizer does not report it; countingCppHeapconstructions against destructions over two setups shows 4 against 2 before this change and 2 against 2 after.The heap is now only created on the snapshotting path, where the params are handed to the
SnapshotCreatorand the heap does get attached.Tests: existing
test/embeddingsuite; no new test, since there is no public API to enumerate detached CppHeaps.Refs: #55337
Disclosure: the code and this description were written by Claude Code, directed and reviewed by @codebytere.