2.0.0-rc.20: createTrackedEffect never re-runs when a dependency is written earlier in the same effect pass

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Valutazione

Difficoltà
4/5
Tempo stimato
3-5 giorni
Idoneità per principianti
28/100
Tipo di issue
Bug
Chiarezza
Abbastanza chiara
Stato di attività
Attiva
Stack tecnologico
javascript, typescript
Ambito
frontend

Direzione di ricerca

The bug is in the reactive core: start with dist/dev.js and the tracked effect's first-run path, where the staged write is propagated before the effect links its dependency, and the staleReader / _reruns logic that does not cover EFFECT_TRACKED nodes. Run the two repro snippets in the issue to confirm the logged values are [0] instead of [0, 1]. Done when both cases log [0, 1] and the existing tracked-effect tests still pass.

Scritto dal modello di indicizzazione a partire dal testo della issue.

Descrizione

Describe the bug

A createTrackedEffect whose dependency is written in the same effect pass, before the tracked effect's first run, reads the committed (old) value and never re-runs once the write commits.

Two common shapes:

  1. another effect writes the dependency on its first run;
  2. a parent's onSettled writes a signal passed to the child as a prop.

createEffect(compute, fn) sees the write in both cases (its effect runs again with the new value), so the difference is specific to the tracked effect. A write made by the component's own onSettled, or after the first flush, is seen.

Your Example Website or App

Self-contained repro below (no external link).

Steps to Reproduce the Bug or Issue
import { createEffect, createSignal, createTrackedEffect, flush, onSettled } from 'solid-js'
import { render } from '@solidjs/web'

// 1. Written by another effect on its first run
const log: number[] = []
function C() {
  const [s, setS] = createSignal(0)
  createEffect(() => 1, () => { setS(1) })
  createTrackedEffect(() => { log.push(s()) })
  return null
}
render(() => <C />, document.body)
flush(); await Promise.resolve(); flush()
console.log(log) // [0]  — expected [0, 1]

// 2. Prop written by the parent's onSettled
const log2: number[] = []
function Child(props: { v: number }) {
  createTrackedEffect(() => { log2.push(props.v) })
  return null
}
function Parent() {
  const [s, setS] = createSignal(0)
  onSettled(() => { setS(1) })
  return <Child v={s()} />
}
render(() => <Parent />, document.body)
flush(); await Promise.resolve(); flush()
console.log(log2) // [0]  — expected [0, 1]

Replacing createTrackedEffect(() => log.push(s())) with createEffect(() => s(), (v) => log.push(v)) logs [0, 1] (resp. ends on 1) in both cases.

Expected behavior

The tracked effect re-runs with 1 after the write commits, as createEffect(compute, fn) does.

Screenshots or Videos

No response

Platform
  • solid-js / @solidjs/signals / @solidjs/web: 2.0.0-rc.20 (client build)
  • Reproduced in Chromium (Vitest Browser Mode) and jsdom
  • OS: Linux
Additional context

Reading dist/dev.js: the tracked effect's first run is enqueued on the heap and runs in the user effect queue; the staged write seems to have been propagated to subscribers before the tracked effect linked its dependency, so the commit at the end of the flush notifies nobody. The stale-reader re-derivation (staleReader / _reruns) does not appear to cover EFFECT_TRACKED nodes.

Impact: in an app migrated from 1.x, this silently froze several views on their initial value (a page stuck on "loading", a PDF page indicator, tab state restored from the URL). We worked around it by converting tracked effects to createEffect(compute, fn).

Lingua principale
TypeScript
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