The global Trakt lock is acquired by SchedulerService.RefreshTraktLists /
MatchTraktLists (and TraktController) and released only when the *terminal*
message of a batch — the one carrying Unlock: true (list == traktLists.Last())
— is processed by WorkerService, whose handler (AddTraktListHandler /
MatchTraktListItemsHandler) calls IEntityLocker.UnlockTrakt() in a finally.
WorkerService.ExecuteAsync breaks out of the read loop on
stoppingToken.IsCancellationRequested (and exits on channel completion /
reader cancellation) BEFORE processing the next message. If shutdown lands
after a batch is enqueued but before its terminal Unlock: true message is
handled, UnlockTrakt() never runs and the in-memory Trakt lock leaks for the
rest of the process lifetime (subsequent Trakt operations 409 forever).
Fix (option a): make the batch-release loss-tolerant with a compensating
release in a finally around the read loop — if the Trakt lock is still held
when the worker stops, release it. Chosen over tracking pending ownership
(b) because the lock is a global singleton and WorkerService is its sole
batch-release site, so "held at shutdown" unambiguously means "the terminal
release was lost"; covers all three exit paths (break / channel completion /
cancellation) in one place. Same lock-lifecycle class as #231/#233/#234.
Regression test: WorkerServiceTests gates the first (non-terminal) batch
message on the stopping token, then StopAsync-cancels so the worker breaks
before the terminal Unlock: true message — asserts the lock is released and
the terminal message was never processed. Proven non-vacuous: inverting the
finally condition fails the test.
Backend-only; no controller/DTO/SPA/OpenAPI impact.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
timothyandClaude Opus 4.8
d02f953922