fix: merge batches #16866
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fix: merge batches #16866
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🦋 Changeset detectedLatest commit: a50d0ec The changes in this PR will be included in the next version bump. This PR includes changesets to release 1 package
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| moving back to draft, some more improvements incoming |
Comment on lines -18 to -27
| // TODO why is this necessary? why isn't `await tick()` enough? | ||
| await Promise.resolve(); | ||
| await Promise.resolve(); | ||
| await Promise.resolve(); | ||
| await Promise.resolve(); | ||
| await Promise.resolve(); | ||
| await Promise.resolve(); | ||
| await Promise.resolve(); | ||
| await Promise.resolve(); | ||
| flushSync(); |
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😆 I saw this while I was working on async SSR and I was really hopeful we could murder it at some point
dummdidumm reviewed Sep 30, 2025
…to merge-batches
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This is part of a project to update some of the async batching logic to handle a few edge cases that have cropped up.
The observable change here is that if you have an
awaitexpression that runs twice, and the second one somehow resolves before the first, they are no longer forced to resolve in linear order. The easiest way to see it is in this example — clicka++thenb++in quick succession:main— the fastb++update is blocked on the slowa++updateb++update occurs, followed by thea++updateTo make this work, whenever a batch is committed, we essentially 'rebase' other pending batches on top of the newly applied state. In the example above, when we commit the fast
b++update, we re-run any async effects that depend onbin the context of the pendinga++batch.Before submitting the PR, please make sure you do the following
feat:,fix:,chore:, ordocs:.packages/svelte/src, add a changeset (npx changeset).Tests and linting
pnpm testand lint the project withpnpm lint