Batch updates in flushSync#5175
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Previously, flushSync temporarily configured options.debounceRendering to execute every scheduled render immediately. This made updates synchronous, but it also caused each state setter to render independently instead of batching all updates performed inside the callback into one synchronous commit. Capture the scheduled render callback while the user callback runs, then flush it once before returning. The previous debounce function is restored in a finally block. Mirrors #5173 (v10.x).
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Size Change: +12 B (+0.08%) Total Size: 15.8 kB 📦 View Changed
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coverage: 99.341% (+0.8%) from 98.492% — flush-sync-batch-main into main |
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Summary
Main mirror of #5173.
Make
preact/compat'sflushSyncbatch updates performed inside its callback.Previously,
flushSynctemporarily configuredoptions.debounceRenderingto execute every scheduled render immediately. This made updates synchronous, but it also caused each state setter to render independently:The example above could render twice instead of batching both updates into one synchronous commit.
This change captures the scheduled render callback while the user callback runs, then flushes it once before returning. The previous debounce function is restored in a
finallyblock.Results
Measured on the v10.x branch (#5173) with Octane's nested update benchmark:
Non-batched update timings remain unchanged.
compat.mjsgrows by 14 B brotli.The batching test is mirrored as well (
unstable_batchedUpdates.test.jspromoted to.jsx).