fix(EffectComposer): fix StrictMode composer leak, guard against r3f reorder bug - #353
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…reorder bug EffectComposerImpl was created inside useMemo, which doesn't guarantee its cleanup runs before React discards a memoized value - this leaked the composer (and its WebGL resources) under StrictMode. It's now created and disposed inside a useState/useEffect lifecycle instead. Pass collection walks the real r3f instance tree (group.current.__r3f .children) and rebuilds the pass list from scratch whenever it or the composer changes, so the order always matches current JSX - including through wrapper components - after a reorder or a remount. While testing the reorder case, found a genuine bug in r3f's host config: when React moves (not remounts) an existing child - e.g. a key-preserving reorder of a keyed effect list - insertBefore/ appendChild splice the moved instance into its new slot without detaching it from the old one first, leaving a stale duplicate in Instance.children. Worth reporting upstream. Added a cheap dedupe (keep each object's last occurrence, sorted by that position) that recovers the correct order either way and is a no-op when the bug isn't present. Also widens `children` from JSX.Element | JSX.Element[] to ReactNode, which was rejecting the common `condition && <Effect/>` idiom (that expression is `false | Element`, and `false` isn't assignable to either half of the union). The tree-walk already tolerates arbitrary children gracefully - it just filters for `instanceof Effect || instanceof Pass` - so the stricter type wasn't buying any actual safety. Replaces the old root-level EffectComposer.test.tsx (superseded, predates this suite and used a different mock-root setup) with a suite covering pass registration/composition order, StrictMode disposal, and the reorder/dedupe behavior above. (ColorAverage-specific dispose coverage lands with the primitive-effect dispose fix, a few commits later - ColorAverage doesn't dispose itself until then.)
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The bug was addressed here: pmndrs/react-three-fiber#3808 I'll cut a release after doing some quick hardening checks. |
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R3F v9.7.0 is out so I think remove the workaround (verify that it works correctly too) and then this is ready to go. |
…3f 9.7.0 r3f 9.7.0 fixes the reconciler bug this workaround existed for: internal instance children were drifting out of sync on a keyed reorder (reported upstream by us, fixed in pmndrs/react-three-fiber#3808). With the fix in place, group.current.__r3f.children no longer contains a stale duplicate after React moves a keyed child, so the dedupe step is no longer needed. Bumped @react-three/fiber to ^9.7.0 and removed dedupeByLastOccurrence, reading groupInstance.children directly. Verified empirically: the existing reorder-with-key test passes on 9.7.0 without the workaround, and fails with the exact same symptom as before (Expected EffectPass with 2 effects) when temporarily downgraded back to 9.6.1 with the workaround still removed - confirming this is the actual upstream fix taking effect, not a coincidence.
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Bumped the dependency and dropped dedupeByLastOccurrence accordingly. All tests passed. Also verified empirically. |
krispya
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Jul 31, 2026
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Fixes #270
EffectComposerImpl was created inside useMemo, which doesn't guarantee its cleanup runs before React discards a memoized value - this leaked the composer (and its WebGL resources) under StrictMode. It's now created and disposed inside a useState/useEffect lifecycle instead.
Pass collection walks the real r3f instance tree (group.current.__r3f .children) and rebuilds the pass list from scratch whenever it or the composer changes, so the order always matches current JSX - including through wrapper components - after a reorder or a remount.
While testing the reorder case, found a genuine bug in r3f's host config: when React moves (not remounts) an existing child - e.g. a key-preserving reorder of a keyed effect list - insertBefore/ appendChild splice the moved instance into its new slot without detaching it from the old one first, leaving a stale duplicate in Instance.children. Worth reporting upstream. Added a cheap dedupe (keep each object's last occurrence, sorted by that position) that recovers the correct order either way and is a no-op when the bug isn't present.
Also widens
childrenfrom JSX.Element | JSX.Element[] to ReactNode, which was rejecting the commoncondition && <Effect/>idiom (that expression isfalse | Element, andfalseisn't assignable to either half of the union). The tree-walk already tolerates arbitrary children gracefully - it just filters forinstanceof Effect || instanceof Pass- so the stricter type wasn't buying any actual safety.Replaces the old root-level EffectComposer.test.tsx (superseded, predates this suite and used a different mock-root setup) with a suite covering pass registration/composition order, StrictMode disposal, and the reorder/dedupe behavior above. (ColorAverage-specific dispose coverage lands with the primitive-effect dispose fix, a few commits later - ColorAverage doesn't dispose itself until then.)