1854921 - Scripts in closed tabs keep using 100% of a CPU core

Status: NEW

(Core :: Performance: General, defect)

Description

[Florian Quèze [:florian]]

Steps to Reproduce:
Not sure if I can reproduce, but I had 2 tabs showing the local homepage of an Enphase Envoy gateway (ie. https://envoy.local/). The macbook was asleep (on battery) for the entire night. When I came back to my laptop this morning, I noticed the two efficiency cores were at 100%. The system Activity Monitor showed the processes using the CPU were Nightly content processes. about:processes (and a quick profiling session) showed that it was the tabs of the Envoy gateway that were misbehaving.
Using about:processes I closed the tabs.

Expected Results:
The CPU use should have gone down.

Actual Results:
The CPU use remained, and the memory use kept growing. I had to kill both content processes.

Profile URLs:

• Profile captured from about:processes: https://share.firefox.dev/3PMDURH
• Longer profile using the Nightly profiler preset: https://share.firefox.dev/3RyiKba

System configuration: Macbook Pro M1 Max.

Notice that the profiles contain "JS::InterruptCallback - https://192.168.1.158/backbone/application.js?version=07.00.20" markers every second. I think in that callback we should check if the page still exists, and if it doesn't, stop the scripts.

Comment 1

[Mayank Bansal]

bug 1848647 shows similar behaviour of activity not stopping in closed tabs.

Comment 2

[Andrew Creskey [:acreskey]]

The Performance Impact Calculator has determined this bug's performance impact to be medium. If you'd like to request re-triage, you can reset the Performance Impact flag to "?" or needinfo the triage sheriff.

Platforms: [x] Windows [x] macOS [x] Linux [x] Android
Impact on browser: Causes noticeable jank
Websites affected: Rare
[x] Causes severe resource usage
[x] Able to reproduce locally
[x] Bug affects multiple sites