Reporting bug in 18.04

[barking63]

About once a day, Ubuntu 18.04 slows to a crawl and then stops responding because Firefox, Web Content, or kswapd0 starts hogging the CPU (sometimes >100% use).

I believe this is a bug and would like to report it as such, but I need some advice about how to gather the information required (https://help.ubuntu.com/community/ReportingBugs) to file a Launchpad report.

Because this is not a crash, no crash file is generated. Because the system becomes unresponsive, I generally cannot open a terminal and then open top after the problem occurs. And because when I am able to open top, one of three different processes seems to be at fault, I am not sure which package to report the bug against.

Any suggestions about how to gather the required information?

Thank you.

[Autodave]

18.04 has been out for awhile now and I really don't see any posts here with that problem. Are you sure that your equipment isn't at fault? Could you give us the specs on your machine?

To me, it sounds like an overheating problem.

[barking63]

Thanks for the quick reply.

There are several similar bug reports for 18.04, but I wasn't able to determine from the reports whether they are the same or merely superficially similar. The Launchpad bug numbers are #1759734, #1788989, #1764597, and possibly #1759734.

The machine is a Lenovo E460 with four Intel Core i3-6100U CPUs @ 2.3GHz, 4 GB RAM, and a 250 GB SSD.

Question about your hypothesis: Do you believe that overheating would *cause* excessive CPU usage? Or that it would *result from* excessive CPU usage?

[Autodave]

Memory overheating could cause that. The CPU running at 100% could definitely cause that.

Do you hear the fan running? Are the inlet / outlet vents unblocked? Have you tried blowing compressed air through the unit? (Please make sure that unit is shut down first.)

[barking63]

Thank you. I haven't tried compressed air but can do so.

The fan is definitely running when the CPU is at 100%. Inlet/outlet vents are unblocked, clean, and free of significant dust. I've installed psensor and will keep an eye on load and temperature and see if anything jumps out.

Whatever the role of heat in the problem, *something* is still causing the CPU to run at 100%, and I'm assuming it's the CPU load that's causing the system to grind to a halt. IMO, browsing a static web page (no gaming or video), even having half a dozen tabs open, shouldn't do this. And FWIW I never had this problem in 16.04; it began a few months ago after I did a clean install of 18.04. Hence my supposition that it's a software issue.

[Autodave]

Another thing that I thought of: are you using an ad blocker? Some of them will grind a machine to a halt. uBlock is a decent one to use if you must.

[speartip]

Following on from Autodave, if Firefox is causing your problem, try disabling all the addons & see if the problem goes away. If it does, enable them 1 by 1 to see which is causing the issue.

[barking63]

Thanks for the suggestions, but I don't have any adblockers or other Firefox extensions installed. The only extensions listed at about:support are the search engines that come pre-installed.

[barking63]

Still working on this. Tried Firefox in safe mode, but no improvement. Hardware temperatures are fine at 40*C or so.

Firefox and "Web Content" are still consuming excess resources. For example, merely opening Morningstar.com's home page sends Firefox to 40% + Web Content 80-115% CPU use. Having two or three pages running at once is enough to freeze up. Percentages are much reduced if I turn off Javascript, but of course most web sites don't work without Javascript. As far as I recall, this problem is new to 18.04, in that I never had trouble with it using 16.04.

[ra7411]

Still working on this. Tried Firefox in safe mode, but no improvement. Hardware temperatures are fine at 40*C or so.

Firefox and "Web Content" are still consuming excess resources. For example, merely opening Morningstar.com's home page sends Firefox to 40% + Web Content 80-115% CPU use. Having two or three pages running at once is enough to freeze up. Percentages are much reduced if I turn off Javascript, but of course most web sites don't work without Javascript. As far as I recall, this problem is new to 18.04, in that I never had trouble with it using 16.04.

Do you get high cpu usage and overheating w/ different browsers?
I've been using FF for a couple yrs and it sometimes runs the cpu pretty hard for no apparent reason. I use System Monitor to kill FF, do a FF restart and restore, and everything is fine again.