What process created this X11 window?

https://unix.stackexchange.com/questions/5478/what-process-created-this-x11-window

by signa11 • 3 years ago

120 76 3 years ago

unix.stackexchange.com

H8crilA• 3 years ago

Didn't use a magnetic needle and a steady hand, I am disappointed.

yrds96• 3 years ago

Neither butterflies

calvinmorrison6• 3 years ago

Why is x11 so backwards?

On Wayland, each window is a composer, each component that makes up a screen is a compositor. Don't mid them up. Simply put each window manages their own process tree as its much cleaner. Its very simple. What you need to do is simply install dbus-systemd and issue SummonPoettering which will give you a clean docker workspace. Simply put this is far superior to X11. In short on Wayland, you only need to push one button to kill an errant window - the power button

notpushkin2• 3 years ago

Not if running on Ubuntu! They've replaced Docker with Snap, so you will have to dbus into ~/snap and patch the hook into the package. Of course, this will not work with the inferior Flatpak apps (which you shouldn't be using anyway as they are buggy and not as cool as snaps).

password4321• 3 years ago

I left Ubuntu because of snap, still haven't heard anything positive so seems like the right move so far.

tuyiown• 3 years ago

Well a definitive press of the power button seems the good way of killing a window, as such notion simply shouldn't exist. One could also argue that those who complains in sarcasm about such unnecessary longings should do the same.

dig1• 3 years ago

In the future, someone will (re)invent wayland-compose.yaml and announce that as the second-best thing after sliced bread. Imagine that technology - each window is a separate container! Our ancestors would be so proud. Then, you start your browser via "wayland-compose up" and that will load 50 additional containers via dbus-systemd, because "that is the only proper way" to run your application.

pests2• 3 years ago

And we thought chrome was genius to introduce one process per tab. One container per tab, its better than one VM per tab.

bigbillheck• 3 years ago

Why is x11 so backwards?

Hasn't it been pretty much ossified for the last 30 years?

spellcard1992• 3 years ago

Under Wayland with Gnome (it's gnome-specific), I recently learned you can kill windows by using Looking Glass:

  // 1. Open looking glass: Alt+F2 > lg
  // 2. Use picker to pick window (button on the top left corner).
  // 3. Now an object r(0) of type MetaSurfaceActor is available in the
  //    gjs console (or some other number if you've already used it).

  // To get pid:

  r(0).get_parent().get_parent().get_meta_window().get_pid()

  // To kill window and process:
  
  r(0).get_parent().get_parent().get_meta_window().kill()

Reference for what those .get_parent() refer to: https://gitlab.gnome.org/GNOME/mutter/-/tree/fc1de744/src/co...

yjftsjthsd-h3• 3 years ago

...wait, does Wayland not have a drop in replacement for xkill?

cbm-vic-20• 3 years ago

Why is x11 so backwards?

Because it was built in a different time. Back in the 80s and early 90s, X11 provided a way for institutions and companies to mix-and-match their hardware and software environments, each with different capabilities. They would have big iron running expensive software and cheap(er) terminals that could display those applications across a campus.

In a university environment, before there was a PC and network in every dorm room, before laptops were a thing, this was awesome. You could walk up to any workstation or X11 terminal on campus, and immediately have access to all of your applications, files, and everything else. And when PCs and networking came to the dorms, you could get an X server for your PC and do the same.

But those days are long past; the networking use case, which was one of the most important aspects of X11, is pretty much no longer relevant. It's really surprising that Wayland still hasn't completely taken over, and they still haven't figured out how to handle certain interprocess communication that would allow screen sharing and other common desktop functionality.

calvinmorrison6• 3 years ago

I felt my comment was so dripping with sarcasm nobody would miss it. SummonPoettering??? Yet like a moth to a flame you missed the point and jumped right into the reasons x11 sucks

pjmlp4• 3 years ago

While true, it wasn't the only protocol for doing that, just the one that won mostly due to OSF/Motif politics, when GNU/Linux came to be that was already pretty much settled.

erik_seaberg3• 3 years ago

I’m still predicting that Wayland will become an implementation detail of web browsers and some games. It doesn’t make sense for every app to render pixels in software and stream them from a datacenter, not for every desktop to have its own copy of every app.

Izkata• 3 years ago

Simply put each window manages their own process tree as its much cleaner. Its very simple.

And not correct: Processes can have multiple windows. Or no windows.

lupusreal• 3 years ago

High grade sarcasm? You had me going until the power button part.

dontlaugh5• 3 years ago

I suspect this is satire.

calvinmorrison6• 3 years ago

The fact 5 commenters did not understand it shows how willingly people will put up with the limitations of their software and diss the software they don't like.

Surely the summoning of Leinart Poettering's spirit to find dead Pids in Waylands Hades was a dead giveaway

l72• 3 years ago

Things can get really complicated with x11 when you have processes running on remote machines or using XEmbed.

With XEmbed, what may look like a single window is actually multiple windows all managed by different processes with their own render loops.

Speaking of XEmbed, many years ago, we had an application that ran complicated visualization pipelines. We wanted to add a modern GUI around it to configure it and provide interaction. We didn't have the ability to rewrite the original application, so we wrote a Gtk GUI and used XEmbed to embed the other process in it, then used a unix socket to send commands back and forth. To the user, it was seamless and worked really well!

thriftwy• 3 years ago

X11 is a network protocol. The process which created this X11 windows could be on a different box, running in the kernel or have the whole X11 exchange replayed from the magnetic tape.

nwatson• 3 years ago

The posed question addresses this in the second paragraph, after the very short first paragraph.

jameshart2• 3 years ago

Presumably which of these states of affairs pertains to a specific window is, though, at some level knowable. The question of which process created the window is not necessarily bounded to ‘processes running in user space on this machine right now’, but something created it.

And 99% of the time the answer will be a locally running process, which makes it a highly pertinent question even without the caveats.

It’s not clever to point out that a question may not have a simple answer and therefore to reject the question as flawed.

arethuza• 3 years ago

"And 99% of the time the answer will be a locally running process"

Depends on the environment - for years I used either an HP X terminal or a PC running an X server and the one thing I could be confident about in both cases was that the process wasn't running locally.

Mind you - that wasn't recently!

cduzz6• 3 years ago

From a 2020's perspective, X11 is deeply weird.

It was written back when huge enormous servers were the only systems with enough oomph to do anything useful, and those servers had 128mb of ram (think of something like a sun 3/480 with a 33mhz 68030).

It was common to have a room of X terminals each with 1-8mb of ram for a 15-19 inch display (with 1-8bit color). In that context, everything ran on another system, often you'd have processes running on several different systems and you'd have to be careful about managing authorization otherwise people would figure out your DISPLAY and run their programs against your X terminal (innocuous, like 300 Xeyes programs or malicious like a keyboard snooper, depending on where and when).

In 2020 this whole scenario sounds absurd, but it was the way of things from when X11 was designed and through the first 15 years of X being a thing.

In some ways, the question is like asking "what is the process ID that generated this http response?"

[edited to add the analogy]

AnotherGoodName• 3 years ago

The easiest way to check who that window belongs to is to run XKillClient for it i.e.: xkill -id 0x1600045 and see which process just died. But only if you don't mind killing it of course!

But but but what does xkill use internally to figure this out. Can we just use that?

kimixa• 3 years ago

That's not mapping a PID to the window though - it's just destroying a window ID and seeing what happens to error out - which might not happen if the app was written to handle the window being destroyed outside it's control, or it's running on a different machine where you won't see any error output/a process dying.

hawski• 3 years ago

https://gitlab.freedesktop.org/xorg/app/xkill/-/blob/master/...

It literally is using XKillClient - https://linux.die.net/man/3/xkillclient

You can kill the connection of another client if you know its id. That's one of the reasons why we love X11 so much.

Another way, as josefx mentioned, is to kill the PID from _NET_WM_PID window property. This is often used by window managers when they offer to kill an unresponsive application.

josefx• 3 years ago

Quite sure it just uses _NET_WM_PID and fails if it isn't there. At least as far as I remember I had issues terminating my own application with xkill until I set the _NET_WM_PID myself, the framework I used only did the bare minimum to get a window on the screen.

russellbeattie• 3 years ago

Funnily enough, this is how I usually figure out who's using a long running, but unknown server process.

Kill it and quietly listen to see if anyone in the office immediately screams. If so, quickly restart it and log out. Otherwise move on with your day, and wait for any angry emails.

superdisk• 3 years ago

So wild, I googled this exact thing yesterday and got to the same stackoverflow post. And now it's on the first page of HN.

mmh0000• 3 years ago

This has happened to me a few times with HN.

I suspect HN is really run by a hyper-intelligent A.I. which is guiding us all to a brighter future.

kazinator2• 3 years ago

You're discounting billions of people to whom this didn't happen, because of which they didn't make a HN comment about it.

phendrenad2• 3 years ago

Nah someone with Wikipedia database access probably looks for obscure article hits and submits them to HN for the karma.

_a_a_a_• 3 years ago

Or a phone-home keylogger

jprd• 3 years ago

dang?

What process created this X11 window?

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