High CPU use in Firefox when Floccus is or was active

[Halvar10]

I'm not really able to find out what is really happening, which is why I'm no comfortable with opening an issue yet. I'm not really familiar with how Firefox extensions work, so I'll need help finding out where to look.

For weeks, I have been having a problem on one machine with Firefox (on Windows 10) when Floccus runs.

Namely, one of Firefox's threads is using 20 to 30% of my CPU all the time, and then FF crashes every time I close it.

When I close Firefox, the thread still continues to run at that high CPU load. and a minute or so after I closed it, Firefox crashes and a Firefox crash dialog comes up. The crash log, as far as I understand it, only says that the "quota manager", whatever that is, didn't respond in time, so a timeout occurred:

MozCrashReason: MOZ_CRASH(Quota manager shutdown timed out)
[...]
ProductID: {ec8030f7-c20a-464f-9b0e-13a3a9e97384}
ProductName: Firefox
QuotaManagerShutdownTimeout: idb: LiveDatabases: 1 (DirectoryLock:1|Transactions:10037|OtherProcessActor:1|Origin:moz-extension://aaDDDDDD-DaDD-DDDD-aDDD-aaDaaaDaaaDa|PersistenceType:default|Closed:1|Invalidated:1|ActorWasAlive:1|ActorDestroyed:1)

The process with the CPU load seems to be the main Firefox process, (it has the lowest PID of all Firefox processes running).

Floccus Syncs (with Nextcloud) happen normally, everything seems to be fine with that. One of the syncs is quite big, but it runs without a problem.

It doesn't happen when I deactivate Floccus and restart Firefox, but just deactivating Floccus doesn't stop the high CPU load, I have to close Firefox and restart, and then the high CPU load doesn't happen.

The Firefox process manager doesn't really help, it shows that the "Firefox" process task takes between 99% and 140% of the CPU, whatever that means. Whenever Floccus syncs, the "extensions" task goes up for a while to also about 90%, but goes down after sync is done. So the problem is in the Firefox process, but as I said, it only happens when Floccus was activated in that session.

While I was writing this, the high CPU load diappeared for a minute or so, but then it came back.

Any ideas what I could check? Thanks for any help.

[marcelklehr]

Hello @Halvar10
Thank you for raising this issue! Please open a proper issue for this, so I can help troubleshoot 🙏

[Halvar10]

Hi Marcel,

strangely, the issue has disappeared "by itself" after weeks, i.e. without me being aware of doing anything relevant.. I had deactivated Floccus after I wrote the post above with the plan to just activate it every week or so for a sync. Today I reactivated it and FF did not start to become CPU hungry again, not even after a restart of Firefox.

So for now, I'm fine and I assume that it was something unrelated that was just somehow triggered by Floccus being active. If it reappears I'll open an issue.

Thanks a lot for this extension and for the support!

[marcelklehr]

Well, that's always the best outcome, when problems resolve themselves :D Happy bookmarking :)