Bug 197983 – united.com uses 100% of CPU in the service worker process

• Status: NEW
• Component: Service Workers

[Ryosuke Niwa]

The service worker process of united.com sometimes uses 100% of CPU.

[Ryosuke Niwa]

Created attachment 370115 [details]
sample

[Ryosuke Niwa]

Observed on the system safari shipped with macOS Mojave 18E226

[Radar WebKit Bug Importer]

<rdar://problem/50899544>

[Ryosuke Niwa]

I guess https://bugs.webkit.org/show_bug.cgi?id=196585 mitigated this issue to an extent.

[youenn fablet]

https://bugs.webkit.org/show_bug.cgi?id=197580, https://bugs.webkit.org/show_bug.cgi?id=197626 and https://bugs.webkit.org/show_bug.cgi?id=185626 should limit the effect of the underlying bug.

Same with pinterest.com and photos.google.com.

Would be nice if there will be some approval by user like for Geolocation API before the worker installation.

[Geoffrey Garen]

If there were an approval step, what privilege would the user be approving? In this case, I think the privilege was the use of the CPU -- but a webpage already has that privilege (when in the foreground).

Priviledge to run in background (even if webpage is closed)?

[youenn fablet]

(In reply to bobik from comment #8)
> Priviledge to run in background (even if webpage is closed)?

By design, when the last service worker client is closed, the service worker will be stopped. If that is not the case, this is a bug in WebKit implementation.

Ditto for CPU usage, a service worker is not expected to use more CPU than what is allowed for its clients.

Some fixes have been done recently in that area that have shipped in recent Safari Tech Preview.

If you are still seeing such issues, let us know.