RealSense-D435i-G1/KNOWN_ISSUE_stream_memory.md

Known issue: stream frames make browser memory grow

Status: not fixed yet — noted on Olivia's request, 2026-09-29 (camera-sensing R13). No code was changed in this repo.

The defect

For every frame, the GUI builds a new Image() from a data:image/...;base64,... URL and reassigns the canvas width/height. Left open, the page's memory keeps growing: on 2026-09-28 hostpc (32 GB) ran out of RAM and the kernel killed a Firefox process holding ~19.8 GB of shared memory, with several camera GUIs open.

Where, in this repo

• src/frontend/react/src/components/StreamView.jsx — the useEffect on frame (RGB JPEG or depth PNG): new Image() per frame, canvas resized per frame, then detections / the measurement marker drawn on top.
• src/frontend/react/src/components/DepthView.jsx — same pattern for the depth colormap (JPEG) or depth PNG.

When applying the fix to StreamView.jsx, keep drawing the detections and the marker after drawImage, and pass the MIME type (image/jpeg for RGB, image/png for depth) to the Blob.

The running copy of this service is on PC2, not on this PC: fixing this local copy does not fix the GUI in use until it is deployed there.

The fix (same as multi-camera_service, commit dfa0fec)

1. Decode with createImageBitmap: base64 -> Uint8Array -> Blob -> createImageBitmap(blob), then drawImage(bitmap, 0, 0).
2. Call bitmap.close() right after drawing (also on error).
3. Resize the canvas only when the frame size changes (if (canvas.width !== bmp.width || ...)).
4. Drop a frame that arrives while the previous one is still decoding (a decoding flag, no queue).

Reference implementation (a React hook, 40 lines): /opt/docker/sensing/multi-camera_service/src/frontend/react/src/hooks/useJpegCanvas.js.

Measured (multi-camera_service, camera-sensing R11, 2026-09-28)

Headless Chromium, roof stream 1920x1080 at ~15 fps: renderer memory +838 MB between minute 1 and minute 5 with the old code; +5 MB between minute 1 and minute 10 with the fix (+17 MB with a second, 640x480 stream). Probe: /opt/docker/sensing/multi-camera_service/scripts/gui_memprobe.py — it kills the browser above 2 GB of renderer memory or below 6 GB of system MemAvailable; keep that cap when measuring on hostpc.