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[Flight] Skip transferReferencedDebugInfo during debug info resolution - #35795
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When the Flight Client resolves chunk references during model parsing, it calls `transferReferencedDebugInfo` to propagate debug info entries from referenced chunks to the parent chunk. Debug info on chunks is later moved to their resolved values, where it is used by React DevTools to show performance tracks and what a component was suspended by. Debug chunks themselves (specifically `ReactComponentInfo`, `ReactAsyncInfo`, `ReactIOInfo`, and their outlined references) are metadata that is never rendered. They don't need debug info attached to them. Without this fix, debug info entries accumulate on outlined debug chunks via their references to other debug chunks (e.g. owner chains and props deduplication paths). Since each outlined chunk's accumulated entries are copied to every chunk that references it, this creates exponential growth in deep component trees, which can cause the dev server to hang and run out of memory. This generalizes the existing skip of `transferReferencedDebugInfo` for Element owner/stack references (which already recognizes that references to debug chunks don't need debug info transferred) to all references resolved during debug info resolution. It adds an `isInitializingDebugInfo` flag set in `initializeDebugChunk` and `resolveIOInfo`, which propagates through all nested `initializeModelChunk` calls within the same synchronous stack. For the async path, `waitForReference` captures the flag at call time into `InitializationReference.isDebug`, so deferred fulfillments also skip the transfer.
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February 16, 2026 01:09
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Feb 16, 2026
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| }; | ||
| let initializingHandler: null | InitializationHandler = null; | ||
| let initializingChunk: null | BlockedChunk<any> = null; | ||
| let isInitializingDebugInfo: boolean = false; |
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Should this be stashed on the initialization handler? We’d never assign the property so it shouldn’t create more hidden classes in practice
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That won't work, because initializeModelChunk resets initializingHandler = null, so the flag would be lost in nested calls.
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When the Flight Client resolves chunk references during model parsing, it calls
transferReferencedDebugInfoto propagate debug info entries from referenced chunks to the parent chunk. Debug info on chunks is later moved to their resolved values, where it is used by React DevTools to show performance tracks and what a component was suspended by.Debug chunks themselves (specifically
ReactComponentInfo,ReactAsyncInfo,ReactIOInfo, and their outlined references) are metadata that is never rendered. They don't need debug info attached to them. Without this fix, debug info entries accumulate on outlined debug chunks via their references to other debug chunks (e.g. owner chains and props deduplication paths). Since each outlined chunk's accumulated entries are copied to every chunk that references it, this creates exponential growth in deep component trees, which can cause the dev server to hang and run out of memory.This generalizes the existing skip of
transferReferencedDebugInfofor Element owner/stack references (which already recognizes that references to debug chunks don't need debug info transferred) to all references resolved during debug info resolution. It adds anisInitializingDebugInfoflag set ininitializeDebugChunkandresolveIOInfo, which propagates through all nestedinitializeModelChunkcalls within the same synchronous stack. For the async path,waitForReferencecaptures the flag at call time intoInitializationReference.isDebug, so deferred fulfillments also skip the transfer.