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viewer: fix HTTP live-follow OOM via datasetLoaded backpressure + shared pixel mask

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The viewer could grow to ~100 GB RAM when live-following an HTTP broker. The
rc.153 images_in_flight backpressure only throttled imageLoaded; the heavy
per-frame payload rides datasetLoaded, fanned out over ~10 queued cross-thread
connections with no cap. In HTTPSyncDataset follow mode (entered when an operator
clicks an image while following live) RefreshDatasetOnly_i emits a fresh full
dataset every autoload tick with no imageLoaded, so the gate never engaged and
the queued events - each pinning a full JFJochReaderDataset (full-detector
PixelMask + per-image plots) - accumulated without bound.

Backpressure datasetLoaded the same way as imageLoaded: a datasets_in_flight
counter (cap 2), all emits routed through EmitDatasetLoaded_i, and
AutoLoadTimerExpired gated on it (covers HTTPSyncDataset). The window routes the
worker's datasetLoaded through a single OnDatasetReady sink that fans out
synchronously via datasetReady and acks with datasetConsumed. Under load stale
datasets are dropped; the next tick sends the latest.

Share the pixel mask instead of deep-copying it: JFJochReaderDataset::pixel_mask
is now shared_ptr<const PixelMask>, so per-frame dataset copies share the ~72 MB
mask. UpdateUserMask does copy-on-write; JFJochHttpReader caches the mask by
arm_date so a live refresh reuses one shared mask per acquisition.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
This commit is contained in:
leonarski_f
2026-07-09 10:58:10 +02:00
co-authored by Claude Fable 5
parent b4a29ebb32
commit dc8a80f3e0
16 changed files with 120 additions and 44 deletions
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reader/JFJochReader.cpp
+4 -1
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@@ -95,7 +95,10 @@ void JFJochReader::UpdateUserMask(const std::vector<uint32_t> &mask) {
if (!dataset)
return;
auto new_dataset = std::make_shared<JFJochReaderDataset>(*dataset);
new_dataset->pixel_mask.LoadUserMask(dataset->experiment, mask);
// Copy-on-write: the mask is shared with the old snapshot, so edit a fresh copy, not in place.
auto new_mask = std::make_shared<PixelMask>(*dataset->pixel_mask);
new_mask->LoadUserMask(dataset->experiment, mask);
new_dataset->pixel_mask = new_mask;
dataset = new_dataset;
}