Request-path thumbnail generation (REST get_thumbnail and NC preview)
read the full source blob into RAM and decoded it with no concurrency
bound — a first-view gallery of K images stacked K full-size buffers
and K parallel decodes on the blocking pool. The background hook had
the inverse ordering problem: it read the blob eagerly and only then
queued on the decode semaphore, so N concurrent uploads held N
originals in memory while waiting.
All three paths now acquire the decode semaphore first and read the
blob under the permit, capping peak RAM at permits x image size:
- new ThumbnailService::get_thumbnail_from_blob defers the blob read
into the moka init closure (cache and disk hits never touch the
blob); both handlers use it and no longer pre-read.
- get_thumbnail_from_bytes (direct-bytes variant) now also takes a
permit before decoding; shared generate_and_persist core keeps the
two entrypoints duplicate-free.
- generate_all_sizes_background_from_blob (renamed from _from_bytes)
checks blob existence and disk-dedup state, then acquires the
permit, then reads; the redundant pre-read spawn wrapper in
ThumbnailRefreshHook is gone.
https://claude.ai/code/session_01QxwJDHqQhbMkHK333QtMme
Claude
b0f83cfa34