The store caps sqlite at one connection under WAL, so every read queues behind every write #192

2026-08-06T23:01:35+02:00

claude commented

2026-08-06 23:01:35 +02:00

Closes Vikunja #642.

Acceptance criteria and quality gate are in TASK.md on this branch.
Review the review, not the diff — leave comments and the agent will apply them via task start 642.

Closes Vikunja #642. Acceptance criteria and quality gate are in `TASK.md` on this branch. Review the review, not the diff — leave comments and the agent will apply them via `task start 642`.

claude added 1 commit 2026-08-06 23:01:35 +02:00

Keep the store's one connection, delete the seam it cannot survive (V-642) af4eeceb6a

`SetMaxOpenConns(1)` under WAL gives up concurrent reads, and the task
asked whether that costs anything. Measured over a fixed two-second
window, a paced writer against a read loop, three runs per cap:
reads do not queue. Four connections buy 70µs at p50 on a turn that
spends 1.19s in the resident model, and write throughput more than
halves. A 19ms worst case also cannot be the source of the 2.7s router
figure, so that line of enquiry is closed.

What the cap cannot survive is a long-lived transaction. It holds the
only connection, so a second read never completes: two seconds and
`context deadline exceeded`, against 1ms at a cap of four.

`Store.DB` handed out exactly that transaction. It had been there since
the initial commit with no production caller, and its comment described
a loop that never materialised. Its one user was a test helper reading
`delivery_attempts` by raw SQL, which `ListDeliveryAttempts` has covered
since V-390. So the cap stays and the seam goes, and the hazard is gone
by construction rather than by documentation.

`internal/store/conncap_test.go` stays as the standing measurement,
skipped under -short. The comment at the cap and the one in
`internal/ipc/server.go` that leans on it now state the invariant and
cite the numbers.

Measurement: docs/evals/2026-08-07-store-connection-cap.md

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

kami merged commit aed8cac439 into master

2026-08-06 23:04:40 +02:00

Sign in to join this conversation.

1 Participants

Notifications

Due Date

No due date set.

Dependencies

No dependencies set.

Reference: kami/Maven#192