docs/zh/plans/render-pipeline-threads.md M3 (design 3.2): OpenFX crash
isolation moves from "every worker hosts plugins" to a single dedicated
host process, served over NDJSON + shared memory.
- oak-worker --ofx-host mode (src/ofx_host.rs): loads every plugin once,
resolves jobs by the cross-process-stable OFX identifier, and renders
through the same in-process executor the workers used to install.
- oak-render/ofxhost.rs: the single-host client. The render manager
creates and installs it for the Pipeline backend (lazy spawn on the
first plugin job); eval::process_plugin_job prefers it and falls back
to the in-process executor otherwise, so the process backend keeps its
current behavior until M4.
- Data plane: input/output FrameSlotPool pairs (the handshake's input_*
fields are used for the first time). Named clips and the source frame
are written to input slots after the explicit CPU readback; the plugin
output returns through an output slot. Pool size/capacity grow by a
host restart when a job needs more (safe: submissions are serialized
and one job is in flight).
- Crash loop: reader EOF fails the in-flight submit, which respawns the
host and re-posts the same job (frames are read back once); after three
consecutive crashes the client is permanently dead and the evaluator
falls back to a purple frame. The dead child is reaped immediately, and
a submit mutex enforces the one-job-in-flight contract.
- Progress/cancel: the host flushes plugin_progress immediately (live
progress), and reads stdin on its own thread so plugin_cancel takes
effect mid-render at the plugin's next progressUpdate; the sticky flag
resets at progressStart and request_plugin_cancel_all broadcasts to
both the worker pool and the host.
- JobSpec::Plugin / PluginJobPayload carry the plugin type_id (stable
across processes); `--ofx-crash-once` / `--ofx-crash-always` are the
deterministic crash hooks, matching the worker's env hooks.
- Tests: wire round-trips; host unit tests (crash budget, cancel-flag
reset through the factory, source mapping); oak-worker integration
tests against the real host + bundled test plugin (render + progress,
crash respawn and re-post, three-crash give-up, mid-render cancel on
the new slow variant, concurrent submits); eval's purple fallback.
Mike-Solar
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