Hacktoberfest 2026: los issues que los mantenedores marcaron para octubre, abiertos y aptos para principiantes. Explorar issues de Hacktoberfest

Android: snapshots ~10× slower while a looping Reanimated opacity animation is on screen (follow-up to #3558)

Abierto
  • ¿Algo no está bien?
#3,832 0 comentarios 0 reacciones 0 asignados Ver en GitHub

Los mantenedores suelen responder en 1 día

Nadie ha tomado este issue todavía.

Evaluación

Dificultad
4/5
Tiempo estimado
3-5 días
Aptitud para principiantes
48/100
Tipo de issue
Error
Claridad
Bastante claro
Estado de actividad
Activo
Stack tecnológico
android, react-native, typescript
Área
mobile-dev, performance

Línea de trabajo

Start by reading the Android snapshot implementation and the cache-miss handling on the UI thread; the issue does not name specific source files or tests. Compare repeated captures with the opacity loop running and held still, using the provided setup and measurements. Done means identifying and addressing the animation-related snapshot latency while keeping captures successful and including the sheet root.

Escrito por el modelo de indexación a partir del texto del issue.

Descripción

Follow-up to #3558, split out as asked. #3611 (0.21.28) fixed the missing-window capture failure. This issue tracks the remaining latency: Android snapshots are about 10× slower while one small looping animation is on screen.

Setup
  • Screen: a full-height @lodev09/react-native-true-sheet 4.0.0-beta.24 sheet (on Android, a separate dialog window). Its header holds an 8×8 Animated.View whose opacity loops forever with Reanimated 4.5.4: withRepeat(withSequence(withTiming(0.4, 800 ms), withTiming(1, 800 ms)), -1).
  • React Native 0.86.3 (New Architecture), Expo SDK 57, release build.
  • Emulator sdk_gphone64_arm64, Android 16 (API 36), 1080×2400. Host: Apple M5 Max, macOS, shared with other emulators and builds.
  • "Animations off" means window_animation_scale, transition_animation_scale and animator_duration_scale set to 0 before launch. Reanimated reads that as Reduce Motion and holds the dot still. Nothing else on screen changes.
0.21.28, 2026-10-17 (the table requested in #3558)

Same session, same sheet. Host load average was 170–240 for both rounds.

Device animations Snapshot wall time Sheet root in snapshot
On (2 rounds) 4.3–15.1 s 12/12
Off (Reanimated holds the dot still) 0.3–0.5 s 6/6

On the slow captures, the daemon's durationMs matched the wall time (4.1–5.3 s on the ones checked).

0.21.28 vs 0.21.29-nightly.20261019.75 (includes #3790), 2026-10-19

Same app build, same emulator, one session. Each block is 7 snapshot --json calls; the first call is dropped because it reinstalls the shared helper APK. Blocks run in ABAB order. The numbers are the helper's data.androidSnapshot.elapsedMs. Every capture succeeded and contained the sheet root.

Device animations Host load 0.21.28 median (range) nightly median (range)
On 29–41 676 ms (535–1246) 536 ms (301–681)
On 16–27 443 ms (263–1140) 439 ms (302–6664, 1 outlier)
Off 17–24 164 ms (151–232) 40 ms (39–46)

What this shows on our screen:

  • #3790 makes the static capture about 4× faster (164 → 40 ms).
  • With the loop running, it changes little at moderate load: 676 → 536 ms at load 29–41, and 443 → 439 ms at load 16–27.
  • The loop's cost on the nightly is about 11× (40 ms → 440–540 ms), with an occasional multi-second capture (6.7 s once, as load rose).
  • Host load scales the slowdown. The same 0.21.28 measured about 0.5–1.2 s here and 4–15 s at load 170–240.

So the remaining cost seems to come from the animation itself rather than traversal order. That fits your note that Android serves cache misses on the UI thread, which a running animation keeps busy.

Impact and workaround

Anything that snapshots repeatedly (wait, press after a settle, replays) pays this on every capture while a pulsing "live" indicator is on screen. That's common in timers, workouts and live-status UIs. Our workaround is animation scales at 0 on the test emulator, as Espresso suites do. That isn't available when the animation is the thing under test.

Happy to run a build against this screen. I can attach the request logs (requests/*.ndjson) for any of the runs above, or put together a minimal repro app (one TrueSheet sheet with the withRepeat opacity loop).

Lenguaje dominante
TypeScript
Estrellas
5k
Forks
334
Merge medio
12 h 13 min
PR fusionados (30 d)
723

Preparar el entorno

Primeros pasos

  1. Lee el issue completo y luego la guía de contribución del proyecto.
  2. Comenta en el issue que vas a ocuparte — evita que dos personas hagan lo mismo.
  3. Haz un fork del repositorio y trabaja en una rama.
  4. Abre un pull request que haga referencia al número del issue.

Más de callstack/agent-device

Todos los issues de callstack/agent-device

Issues similares

Más issues de TypeScript

Recibe los nuevos issues en tu correo

Un resumen breve de issues de GitHub para principiantes.