getObjects() is on every real host page's path — a click hands back an
object id, and resolving it to a GlobalId/name/type needs the element
tables (the JS layer also builds its GUID index from this call). The
implementation materialised a vector of ElementRef (three fresh
std::strings per element), serialised the entire scene into one JSON
string grown by +=, and UTF8ToString'd the whole thing — several
hundred MB simultaneously alive at ~600k elements. The wasm heap never
returns pages, so that transient became the session's permanent floor.
ViewportCore::visitModelElements hands out one model's elements as
slices into its string table (no per-element copies), and the export
serialises straight from those, one model per batch, reusing one string
whose capacity grows only to the largest model. The JS side accumulates
batches and resolves the same array as before — the page API is
unchanged. Peak is now one model's JSON instead of the scene's.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Dion Moult
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