Decompose: Documented concurrency contract (throughput, per-request bounds, failure semantics) — Phase 2: Per-request bounds (questions 2, 3, 4) #70

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opened 2026-06-22 16:31:51 +00:00 by Mark · 0 comments

Mark commented

2026-06-22 16:31:51 +00:00

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Phase 2: Per-request bounds (questions 2, 3, 4)

Goal: Lock the per-request resource limits.

Specifically:

Per-request timeout? Answer: 60 seconds for digitize, 30
seconds for export. Justify: a 4 MP image at 0.4mm density is
~600K stitches, generated in < 5 seconds; 60s gives 12× headroom.
Per-request memory cap? Answer: 1024 MB. Justify: the raster
pipeline at 4 MP peaks at ~800 MB.
Cancellation? Answer: yes — when the client disconnects, the
worker thread is interrupted within 1 second (set a flag the
pipeline checks between stages; full thread cancellation is unsafe
because of numpy/scipy GIL interactions).

Files:

Modify: docs/concurrency.md (add these 3 answers)

Acceptance:

All 3 questions answered with value, rationale, source.
A test asserts that a request exceeding the timeout returns 504
Gateway Timeout.
A test asserts that a request exceeding the memory cap returns
503 with a clear error.
A test asserts that cancelling the client connection causes the
worker to stop within 1 second.

Depends on: P1 (overall policy).

Decomposed from easystitch#43

## Phase 2: Per-request bounds (questions 2, 3, 4) **Goal:** Lock the per-request resource limits. **Specifically:** 2. **Per-request timeout?** Answer: 60 seconds for digitize, 30 seconds for export. Justify: a 4 MP image at 0.4mm density is ~600K stitches, generated in < 5 seconds; 60s gives 12× headroom. 3. **Per-request memory cap?** Answer: 1024 MB. Justify: the raster pipeline at 4 MP peaks at ~800 MB. 4. **Cancellation?** Answer: yes — when the client disconnects, the worker thread is interrupted within 1 second (set a flag the pipeline checks between stages; full thread cancellation is unsafe because of numpy/scipy GIL interactions). **Files:** - Modify: `docs/concurrency.md` (add these 3 answers) **Acceptance:** - All 3 questions answered with value, rationale, source. - A test asserts that a request exceeding the timeout returns 504 Gateway Timeout. - A test asserts that a request exceeding the memory cap returns 503 with a clear error. - A test asserts that cancelling the client connection causes the worker to stop within 1 second. **Depends on:** P1 (overall policy). --- --- _Decomposed from [easystitch#43](https://forgejo.tail018ac4.ts.net/Mark/easystitch/issues/43)_