RAM & "Image Cache" growth with Chromium-based browsers (Chrome/Edge) despite noVNC 1.7

Description

Hi,

We are experiencing a memory issue with recent Chromium-based browsers where noVNC causes excessive and continuous growth of the RAM usage and the "Image Cache" (as reported by Chrome's Task Manager).

Environment

• Affects Chrome and Edge (Chromium)
• Does not appear to affect Firefox
• Reproduced on both Windows and Linux
• Only affects some machines. We have not yet identified what differentiates affected and unaffected systems.

Background

We first noticed the issue after a recent Google Chrome update (v149, still affected in v150 & v151).

Even with noVNC v1.7 (which includes the change "Received image data is now dropped once rendered, resulting in more efficient memory usage"), the continuous growths are still present on the affected systems.

Even more strangely, it is sometimes possible to reproduce the issue in one browser tab but not another, within the same Chrome instance.

Observed behavior

During a VNC session, the tab process RAM and the "Image Cache" reported by Chromium's Task Manager continuously increase over time and can reach several gigabytes.

Once the growth starts, it does not appear to stabilize. The RAM increasing is not always linear (it can punctually decrease a bit but is globally always increasing) during the session.

Disconnecting / reconnecting during a session does not have affect positively neither the RAM nor the "Image Cache".

Questions

• Could there still be code paths where decoded image data is retained longer than expected?

How to reproduce (on Ubuntu)

prerequisites

wget -P /tmp https://github.com/TurboVNC/turbovnc/releases/download/3.3/turbovnc_3.3_amd64.deb
sudo apt install /tmp/turbovnc_3.3_amd64.deb
sudo apt install mesa-utils

setup

start turbovnc + glxgears

echo pancakes | /opt/TurboVNC/bin/vncpasswd -f > /tmp/rfbauth && /opt/TurboVNC/bin/vncserver -rfbauth /tmp/rfbauth -noxstartup :10 && DISPLAY=:10 glxgears

open noVNC in Google Chrome

https://novnc.com/noVNC/vnc.html?encrypt=0&host=localhost&port=5910&path=&password=pancakes&autoconnect=1

analyze

open Google Chrome / more tools / task manager & display "image cache"

The "image cache" grows indefinitely and never shrinks, even after disconnecting and reconnecting.

with Google Chrome 151.0.7922.71 on Ubuntu 24.04 - noVNC 1.7.0

cleanup

stop turbovnc

/opt/TurboVNC/bin/vncserver -kill :10