mirror of
https://github.com/neondatabase/neon.git
synced 2026-01-07 05:22:56 +00:00
743f6dfb9b
The pagebench integration PR (#6214) issues attachment requests in parallel. We observed corrupted attachments.json from time to time, especially in the test cases with high tenant counts. The atomic overwrite added in #6444 exposed the root cause cleanly: the `.commit()` calls of two request handlers could interleave or be reordered. See also: https://github.com/neondatabase/neon/pull/6444#issuecomment-1906392259 This PR makes changes to the `persistence` module to fix above race: - mpsc queue for PendingWrites - one writer task performs the writes in mpsc queue order - request handlers that need to do writes do it using the new `mutating_transaction` function. `mutating_transaction`, while holding the lock, does the modifications, serializes the post-modification state, and pushes that as a `PendingWrite` into the mpsc queue. It then release the lock and `await`s the completion of the write. The writer tasks executes the `PendingWrites` in queue order. Once the write has been executed, it wakes the writing tokio task.