screensaver is a cpu hog - causing waste of energy

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I don't think this is so much of a bug in Lubuntu as it is a limitation of most VM software in general.

VM software is generally very good at virtualizing a computer's CPU and most other "normal" components (sound, motherboard, etc.). However, graphics hardware is much more difficult to virtualize most of the time due to limitations of the GPU hardware (only some GPUs allow you to "split" one physical GPU into multiple virtual GPUs), and so virtualization software will usually only provide relatively basic graphics capabilities to the VM by default.

XScreenSaver relies on having graphics hardware to display screensavers. When that hardware isn't available, it falls back to using the CPU to render the screensavers. And since the VM software doesn't provide good graphics acceleration to the VM, XScreenSaver puts a large load on the CPU, causing the resource usage spike you're seeing.

The best way to get around this is probably to just disable the screensaver - you should be able to do this by opening the XScreenSaver settings (by going to the Application Menu, searching for "Screensaver", and then clicking "Screensaver). There's a menu on the left-hand side near the top where you can select "Disable Screen Saver", if I remember correctly.

The screensaver is (at least in all existing versions of Lubuntu) an important part of the Lubuntu experience, and disabling it by default in existing releases of Lubuntu would be a feature-breaking change that we would probably not be allowed to make (as Lubuntu is an official Ubuntu flavor and thus has to abide by Ubuntu's rules when it comes to how we do things). And the soon-to-be-released Lubuntu Lunar release has already passed Feature Freeze, so we're probably already stuck with the screensaver enabled by default there. However, we may be able to consider disabling the screensaver by default in a future release of Lubuntu, if we determine that the costs of the screensaver outweigh the benefits of having it enabled by default. For now, disabling it manually is probably the best solution.

thank you for the long explanation. i can understand your point of view and i respect that.

but please understand my point of view

lubuntu is a distro used by hundreds of thousands people, and it's especially being a ressource-saving distro for not so fast or ressource constrained hardware and very likely for virtual environments. it's not that "eye candy bloated" distro as many others.

nowadays, virtualization is very popular and i bet there are much more linux installations running on virtual machines then on real hardware.

trying to minimize energy consumption at such scale DOES make a difference.

it's not a matter of a couple of kWh or some dollars, we are probably speaking of thousands of kWh , which cost a large amount of money and produce a large amount of CO2 and pollutants.

you (and me and us all) have some responsibility, as we can easily make some change via some git commit, which enables people using their electricity and money for more sensible stuff.

regarding "but you can switch it off":
many people don't care, especially where energy prices are low. some may switch to a different screensaver. but many many don't. most likeley because they simply can't easily see, that it's causing significant additional energy consumption.

please, let's care for their bill and for the environment instead of persisting on "eyecandy".

i have checked, how things behave in ubuntu and xubuntu.

in ubuntu, there is no screensaver by default - only black/blank screen .cpu is idling at <1% in a VM :
https://www.debugpoint.com/install-change-autostart-setup-screensaver-ubuntu-linux/

same for xubuntu.

same for kubuntu.

same for linux mint (which is also ubuntu based).

will lubuntu please follow that "strategy" ?

I don't have the authority to decide if Lubuntu will follow that "strategy" by default all by myself, so I can't say what Lubuntu will and won't do in the future. It's definitely something we can consider and change in future releases, but whether we will or not isn't in my power to decide on my own.

However, it's not as simple as a Git commit. There is a process enforced by the Ubuntu development community for changing anything in an already-released version of any official Ubuntu flavor (Lubuntu included). This process reduces the chances of accidental or detrimental changes being made to Ubuntu as a whole. (You can take a look at it at https://wiki.ubuntu.com/StableReleaseUpdates)

This process is very strict, and it prohibits us from making changes like you are suggesting unless we can make a very strong argument that the current behavior is a "bug" in the strict sense (i.e., an error in how software functions that results in an outcome other than what the developer intended or that could cause significant damage even if it is intended behavior). Certainly it can be argued that the needless use of electricity is damaging, but if an update were to be released that disabled the screensaver by default, it would result in many (if not most) existing users of Lubuntu having their screensaver stop working. Having worked with the Stable Release Updates team, they are likely to consider the screensaver vanishing to be more disruptive than the use of excess power.

This is a design decision that needed to be made before a release of Lubuntu went into Feature Freeze. For released versions of Lubuntu, Feature Freeze is long past, and for Lubuntu Lunar (23.04), Feature Freeze hit about a month or so ago. We are free to make a different design decision for whatever version of Lubuntu comes after Lubuntu Lunar (23.04), but the decision is made now and undoing it isn't within our power.

Again, we may consider only blanking the screen (and not displaying a screensaver) in future releases of Lubuntu (23.10 and higher). Whether we will or not isn't something I decide by myself.

(By the way, this is a good discussion, but it may be better if we had this discussion on our Discourse forum at https://discourse.lubuntu.me/. A bug report isn't really the best place to discuss this.)

ok. it doesn't matter if it isn't fixed for the current release . if it's
such problematic, i'd be also fine if it's fixed in the next release.

>Certainly it can be argued that the needless use of electricity is
>damaging, but if an update were to be released that disabled the
>screensaver by default, it would result in many (if not most) existing
>users of Lubuntu having their screensaver stop working

i never told that the screensaver should be disabled by default. it should
only be switched to something cpu/energy friendly and if there is no
 better alternative for flurry, you could simply set it to "mode: blank" in
/usr/lib/X11/app-defaults/XScreensaver and leave it up to the end-user
 to change it to his favourite one.

here is the change that introduced flurry as the default screensaver:

https://phab.lubuntu.me/rDEFAULTSETTINGS0169ba6e57beddd7a519a2dd678b1b652f659b86

does anybody have an estimate/guess how many lubuntu installations
are out there in this world?

@wxl, i have added you to this bug to ping you, because i see you had committed/reviewed that change and i don't know how to contact the original author. hope that's ok. i know that's not the best way to contact people. feel free to unsubscribe again.

manjaro linux: <1% cpu after installation and going idle. no cpu/gpu heavy use screensaver
opensuse leap: <2% cpu

default xscreensaver in lxde desktop in debian11 is "random" and thus may also lead to excessive cpu usage in virtual machine. will do debian reportbug for this