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[server] Periodic KV snapshot initialization races with Replica deletion

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#4,599 2 commenti 0 reazioni 0 assegnatari Vedi su GitHub

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@MaheshS08 ci sta già lavorando.

Dal 13/10/2026.

Valutazione

Difficoltà
4/5
Tempo stimato
3-5 giorni
Idoneità per principianti
53/100
Tipo di issue
Bug
Chiarezza
Abbastanza chiara
Stato di attività
Attiva
Stack tecnologico
java
Ambito
backend, databases

Direzione di ricerca

Start with Replica.delete() and Replica.dropKv(), then trace how closeableRegistryForKv closes PeriodicSnapshotManager and how snapshot initialization runs under kvLock. Use the deterministic regression described in the issue with the existing ReplicaTest fixtures to reproduce the registry-closing window. Done means deletion stops or synchronizes periodic snapshot initialization before the KV registry closes, with the regression confirming no closed-registry IOException is logged.

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

Descrizione

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Fluss version

main (development)

Please describe the bug 🐞

Periodic KV snapshot initialization can race with Replica deletion and attempt to register resources after the Replica's KV registry has been closed.

java.io.IOException: Cannot register Closeable, registry is already closed. Closing argument.
    at AbstractAutoCloseableRegistry.registerCloseable
    at AsyncSnapshotCallable$AsyncSnapshotTask.<init>
    at AsyncSnapshotCallable.toAsyncSnapshotFutureTask
    at SnapshotRunner.snapshot
    at KvTabletSnapshotTarget.initSnapshot
    at PeriodicSnapshotManager.lambda$triggerSnapshot$2

Replica.dropKv() closes closeableRegistryForKv. The registry first sets closed=true, then closes its registered resources, including PeriodicSnapshotManager. A scheduled snapshot can still run between these steps and reach task registration while the registry is already closed.

The manager's close() also does not serialize with snapshot initialization under the tablet's kvLock, so cancelling the scheduled future alone does not cover an initialization already in progress.

Deterministic reproduction

A local regression uses the existing ReplicaTest fixtures and real Replica, RocksDB, snapshot target, runner and registry:

  1. Create a KV leader, write and flush records, and retain the snapshot timer automatically scheduled during leader initialization.
  2. Register a latch-controlled Closeable after the snapshot manager. Call Replica.delete() on another thread and pause resource closing after the registry becomes closed, before the manager stops.
  3. Execute the original scheduled timer, then release the latch and wait for deletion to finish.

This enlarges a valid closing window without mocking the initialization exception. The assertion that no closed-registry IOException is logged fails on both revisions:

Regression Base b530fcc2 PR #4492 19870c605
Retry after snapshot-init failure Fails: no replacement task Passes
Snapshot initialization during Replica deletion Fails: closed-registry IOException Fails: same IOException

Four occurrences were observed during test table deletion. Deletion completed, and no snapshot corruption was established.

Expected behavior

Replica deletion should stop or cancel periodic snapshots cleanly, without allowing snapshot task registration after the KV registry closes.

Solution

Serialize stopping the snapshot manager with snapshot initialization before closing the KV registry and dropping the tablet, while preserving cancellation and cleanup of already registered tasks.

Related: #4489 and #4492 address retry after initialization failure. The closing race exists before that PR and requires a separate lifecycle fix.

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Lingua principale
Java
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Merge medio
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PR unite (30g)
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