DuplicateTaskCompletionException in Firestore ThrottledForwardingExecutor causes fatal crash

Abierto
  • ¿Algo no está bien?
#8,021 1 comentario 0 reacciones 1 asignado Ver en GitHub

Los mantenedores suelen responder en 1 día

@wu-hui ya está trabajando en esto.

Desde el 8/4/2026.

Evaluación

Este issue todavía no se ha evaluado.

Descripción

api: firestore
Description

We're seeing a fatal DuplicateTaskCompletionException crash originating from Firestore's internal ThrottledForwardingExecutor. The crash is a race condition where a TaskCompletionSource is resolved twice — entirely within SDK code, with no app code in the stack trace.

Environment
  • Firebase BOM: 34.11.0
  • firebase-firestore: 26.1.2
  • play-services-tasks: 18.4.0
  • Android versions affected: Multiple (seen on API 30+)
  • Reproducibility: Intermittent — likely a threading race condition
Stack trace
Fatal Exception: com.google.android.gms.tasks.DuplicateTaskCompletionException: Complete with: result ip$a@22e602d
    at com.google.android.gms.tasks.zzw.zzg(com.google.android.gms:play-services-tasks@@18.4.0:1)
    at com.google.android.gms.tasks.zzw.zzc(com.google.android.gms:play-services-tasks@@18.4.0:2)
    at com.google.android.gms.tasks.zzx.run(com.google.android.gms:play-services-tasks@@18.4.0:3)
    at com.google.firebase.firestore.util.ThrottledForwardingExecutor.lambda$execute$0(ThrottledForwardingExecutor.java:54)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
    at java.lang.Thread.run(Thread.java:923)
Analysis

The entire stack trace is inside SDK code — no app-level frames. ThrottledForwardingExecutor uses a semaphore to cap concurrency and falls back to running tasks synchronously on the calling thread when all slots are taken. This appears to create a window where two threads attempt to complete the same Task.

Suggested fix

Guard TaskCompletionSource.setResult() / setException() calls with trySetResult() / trySetException() in the code paths that run through ThrottledForwardingExecutor, or ensure the completion callback can only execute once.

Steps to reproduce

We have not been able to reproduce this on demand. It appears to be a timing-dependent race condition, possibly triggered by network transitions or app backgrounding during in-flight Firestore operations.

Lenguaje dominante
Java
Estrellas
2.6k
Forks
733
Merge medio
2 d 15 h
PR fusionados (30 d)
72

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 firebase/firebase-android-sdk

Todos los issues de firebase/firebase-android-sdk

Issues similares

Más issues de Java

Recibe los nuevos issues en tu correo

Un resumen breve de issues de GitHub para principiantes.