v3.3.97 (UV_THREADPOOL_SIZE 64→8) was a decisive win — mean event-loop-delay at
70 active uploads dropped 200ms→~11ms (18×), rss 577→287MB, renderer healthy in
14/15 windows. But the user reports it is still not perfectly smooth. A focused
multi-agent investigation plus an adversarial review localized the residual to
TWO distinct, separately-measured spike sources:
1. Read-bursts. In the tail windows the file-read histogram inverts: FSReqCallback
climbs to 66-70 against threadpool=8 (~8.75× queue depth) while SimpleWriteWrap
(socket writes) collapses to 4-24 and mean delay rises to 30-42ms. GC is ruled
out (gcMax ≤27ms in every window). The clean inversion at a stable active=70 /
pending=1287 shows the reads are causal, not a symptom of a block elsewhere.
2. A suspected synchronous config-persist stall. save() → load() reparses the whole
electron-config.json — which now carries the 1287-job pending queue nested in
globalSettings plus full history — on every persist (because _atomicWrite nulls
the read cache), then _serializeForDisk JSON.stringify(…, null, 2) of all of it.
One tail sample (max 1021ms, heap spiking to 142MB) fits a large synchronous
structuredClone+stringify, but it is a single confounded point, so this build
only INSTRUMENTS the path rather than asserting the cause.
This release ships one behavioral change (kept to a single variable so the next
log attributes cleanly) plus measurement:
- highWaterMark 256KB→1MB in all five streaming read loops (lib/hosters.js,
doodstream/voe/vidmoly CHUNK_SIZE consts, and the inline value in
clouddrop-upload.js:108 — NOT the 16MB server chunk at clouddrop-upload.js:12).
UV_THREADPOOL_SIZE stays 8. This deepens each stream's read-ahead cushion from
~0.43s to ~1.7s at the per-stream rate, so a stream tolerates the threadpool
queue without starving its socket write, and cuts read-completion callbacks and
per-chunk Buffer allocations ~4×. Byte-correctness is unaffected: Content-Length
is preamble+fileSize+epilogue, independent of chunk size, and the chunk size
never touches the multipart boundaries. Fully reversible; a dedicated read-
concurrency semaphore is held in reserve if 1MB does not clear the bursts.
- config-store.js now times load() (the full reparse, which the account-failed
handler also hits per failure) and the _commit serialize, logging
`config-load …` / `config-serialize wall=…ms bytes=… hist=… queue=…` when the
synchronous work exceeds 20ms. load() is split into a timing wrapper + _loadImpl;
the timer is a no-op until main.js wires configStore.setPerfLog → logInfo.
The renderer batch-drain fix for the one observed 243ms longtask is intentionally
deferred: that jank is downstream of the main-thread read-burst flooding IPC, so
fix#1 should make it self-heal; bundling it would confound the measurement and
touch the progress hot path. All 397 tests pass.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
_uploadChunked read each 16 MB chunk with fs.readSync on the main JS thread — the only one of the five uploaders that blocks synchronously (the other four stream async). Each readSync stalls the whole event loop ~5-9 ms on SSD, 30-100 ms on a slow disk, freezing all progress emits, IPC, renders and every other concurrent upload for that window. The stall scales with the number of simultaneous clouddrop uploads, matching the 'feels laggy while uploading, worse with more at once' symptom at modest CPU (one core pinned, ~40% of 8).
Swap fs.openSync/readSync/closeSync for fs.promises.open + await fh.read + await fh.close. Buffer reuse and the partial-last-chunk subarray view are unchanged. Verified byte-identical to the old loop via SHA-256 over every chunk-boundary case (full chunk, partial last chunk, 2/3/4-chunk files, single byte) before shipping — a chunk-read bug would corrupt the upload.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Last round of targeted wins:
- upload-manager progress callback was allocating a fresh
{ jobId, speedKbs, bytesUploaded } object on every fs stream chunk
(hundreds of times per second per active job). Now a single entry
is created at job start and mutated in place — zero allocations
on the steady-state progress tick.
- upload-manager stats timer's two separate activeJobs.values()
scans (globalSpeedKbs + inProgressBytes) merged into one pass.
- clouddrop-upload.js reuses a single Buffer.allocUnsafe(chunkSize)
across all chunks, taking subarray() only for the tail chunk.
A 1 GB upload no longer allocates 64× 16 MB = 1 GB of short-lived
buffers — real GC relief during many-file batches.
- _resolveUploadLogTarget is now cached; the fallback ladder runs
once per session (or when the user changes the log path / daily-log
date rolls), not on every 500ms flush.
- renderRecentUploadsPanel skips updateRecentSortHeaders on the
append-only fast path — sort state hasn't changed, headers don't
need recomputing.
/upload/complete was failing (non-JSON response, missing fileId, or
post-processing timeout) after all bytes were already on the server,
causing upload-manager to retry the entire multi-GB upload — which
corrupts the server-side file since two uploads end up interleaved.
Now /complete failures are swallowed and sessionId is used as the
file_code fallback. Upload is considered done once all chunks are in.
Upload completes on server but file is still being processed, so
share-link fails. Retry up to 6x with backoff; on final failure, use
fileId-based fallback URL instead of throwing — prevents upload-manager
from retrying the entire multi-GB upload.
