The download/edit child (yt-dlp + ffmpeg) shares one LAN box with the API,
Postgres, and Plex playback. A CPU re-encode pegged every core for ~30s and
starved web requests + playback until it finished. Full-scope S4 mitigations:
- Child self-de-prioritizes at startup (inherited by every ffmpeg/yt-dlp
descendant): CPU nice increment + best-effort idle ionice class + an
OMP_NUM_THREADS budget, all config-gated and independently disable-able.
- Cap the browser-safe re-encode's encoder threads (`-threads`) so a transcode
reserves a core for foreground work instead of claiming all of them.
- Throttle the retention GC's whole-tree orphan sweep (yield IO after each
batch of files) so its rglob can't monopolize disk IO in the API process.
- Idle-back-off the Download Center (2s→15s when nothing queued/running) and
UsageBar (2s→15s when running_jobs is 0) polls; both snap back to 2s on the
next fetch after an enqueue (invalidateDownloads refetches immediately).
Tests: encode_thread_cap (pin/reserve-core/edge), -threads flag presence,
_deprioritize (nice/ionice/OMP branches), GC sweep throttle batching.
Follow-up to user prod testing of 0.51.0:
- re-download now clears job.display_name so the card title + Content-Disposition filename are
re-derived from the freshly-cleaned title (previously an auto-name from an older un-cleaned
title — still carrying a "… views · … reactions |" prefix — survived the rebuild).
- on-disk AND served names are now a strict shell-safe slug: only [A-Za-z0-9._-] survive; every
other char (the "!" the user saw, plus ( ) [ ] & $ ' " ; | ? * …) collapses to "_". The id no
longer uses [brackets] (glob metacharacters). Shared _slug helper for sanitize + display_filename.
- GC gains a 5th pass: sweep on-disk files/dirs no ready asset owns (old accented channel dirs, a
poster from a superseded naming scheme left after a re-download), skipping the dot system trees
and anything newer than an hour so an in-flight download is never touched.
- Tests: slug strips !/$/()[]; rel_path is bracket-free; orphan-sweep keeps owned/system/fresh files.
peter