Screen becomes empty

[ChrisLahaye]

Thank you for your great work. Please let me know if I can help by providing any additional information or performing tests.

Platform

Linux arch 4.18.16-1-ck-skylake #1 SMP PREEMPT Sat Oct 20 08:37:58 EDT 2018 x86_64 GNU/Linux

GPU, drivers, and screen setup

130 chris@arch ~/dotfiles/compton (git)-[master] % glxinfo | grep -i vendor                  
server glx vendor string: SGI
client glx vendor string: Mesa Project and SGI
    Vendor: Intel Open Source Technology Center (0x8086)
OpenGL vendor string: Intel Open Source Technology Center

chris@arch ~/dotfiles/compton (git)-[master] % lspci -k | grep -EA3 'VGA|3D|Display'     :(
lspci: Unable to load libkmod resources: error -12
00:02.0 VGA compatible controller: Intel Corporation HD Graphics 530 (rev 06)
        DeviceName: Onboard IGD
        Subsystem: Hewlett-Packard Company HD Graphics 530
        Kernel driver in use: i915

Environment

XFCE4

Compton version

v3 and v3-rc2-16-g06d8792

Compton configuration:

Default configuration and /etc/xdg/compton.conf.example
Tried any combination of options

Steps of reproduction

1. compton --config /dev/null

Expected behavior

Windows to be visible

Current Behavior

Screen becomes empty

Other details

https://youtu.be/WrTd4yi8FcA

I remember having this problem on your fork a long while ago, then it was fixed for a while, now it is back again.

[yshui]

Have you tried the glx backend?

[yshui]

OK, there seems to be some problem in the window stacking code. I will look into it.

[ChrisLahaye]

Have you tried the glx backend?

Yes, same results

OK, there seems to be some problem in the window stacking code. I will look into it.

Thank you, well appreciated

[yshui]

What happens when you have more windows open? What window manager do you use? (I was assuming xfwm4).

[ChrisLahaye]

What happens when you have more windows open? What window manager do you use? (I was assuming xfwm4).

I am indeed using xfwm4. I get the same results independent of the number of windows or screens.

In the screen recording, the first part is without configuration, here it disappears instantly (same as with the shipped configuration sample). The second part is with my own configuration (https://gist.github.com/ChrisLahaye/1f11ce1d1748889064df1010254984ce), here it disappears when opening an overlay (plank, notification) or menu (context menu, whisker).

[yshui]

I cannot reproduce this on a new xfce4 install. So I'm afraid you will have to help me debugging this issue.

Can you run xwininfo -root -tree before running compton --config /dev/null, and paste the output here? Please also include compton's output.

[ChrisLahaye]

Output of xwininfo -root -tree: tree.txt
Output of compton --config /dev/null: restack_win(0x03e00eea, 0x02e08277): Failed to found new above window. and then the screen becomes empty.

[yshui]

A wild guess, but if you kill xfce4-panel (which will kill your panel) before starting compton, does it still happen?

Also what happens if you kill redshift before starting compton?

[ChrisLahaye]

Same results with xfce4-panel and redshift killed.

[yshui]

Hmmm. I am out of ideas.

So I enabled a bunch of debug outputs in the debug-30 branch, can you run it and paste the output here? It can potentially generate a lot of output, so you better redirect it to a file: <path>/compton >log 2>&1.

[ChrisLahaye]

log.txt
As attachment the log. Thanks again

[yshui]

@ChrisLahaye from the log file I can see compton did try to paint something, somehow nothing is painted on screen....

You said this happen on GLX as well, right? So if you are familiar with apitrace, could you use that to capture a trace of compton with the GLX backend? (It will capture all window content, so don't open too many windows to minimize the size of the capture).

[ChrisLahaye]

compton-next.trace.log
compton-debug.trace.log

As attachment the traces. Did my best to minimize the size.

[yshui]

Sorry, did you happen to capture compton's output when you captured these traces?

[yshui]

If you are going to do the capture again, could you do the following things at the same time:

• Run under apitrace and get the trace
• --config /dev/null --backend glx
• Build from debug-30 (it is updated with a few more commits)
• Capture the outputs of compton

Thanks!

[ChrisLahaye]

apitrace trace compton --config /dev/null --backend glx > output.log
output.txt
compton.trace.txt

Thanks again for your efforts

[yshui]

No, thank you for sticking with me.

But sorry, I wasn't clear enough. You need to capture the output with >output.log 2>&1, otherwise you loss everything printed on stderr.

[ChrisLahaye]

Oops

apitrace trace compton --config /dev/null --backend glx 2>&1 > output.log
output.txt
compton.trace.txt

[yshui]

@ChrisLahaye Sorry, but the order of redirection is important[1]. It has to be >output.log 2>&1, not 2>&1 > output.log

[1]: https://unix.stackexchange.com/questions/37660/order-of-redirections

[ChrisLahaye]

Ugh didn't know the difference, should have just followed the instructions 👍

apitrace trace compton --config /dev/null --backend glx >output.log 2>&1
compton.trace.txt
output.txt

[yshui]

Hmm, so compton apparently decided none of your windows are worth painting...

I suspect maybe there's a big window that covers up the whole screen...

I will add more debug prints...

[ChrisLahaye]

@yshui cool thanks, let me know when you have updated the branch

[yshui]

I updated the branch. This time you don't need to run apitrace

[ChrisLahaye]

compton --config /dev/null --backend glx >output.log.txt 2>&1
output.log.txt

[yshui]

Ah, so all your windows are completely transparent somehow.

Now we just need to figure out why...

[yshui]

I added print message to print out the opacity when they are updated. Can you try debug-30 again?

Also it has a slight chance of just fixing you problem.

[ChrisLahaye]

output.log.txt

Thank you

[yshui]

Hmm, do you have any idea why all your window is considered transparent. Can't seems to find a reason why compton would do that...

[ChrisLahaye]

No idea, I generated the log and tried without any programs running. I will try later with another GTK theme, maybe the theme uses transparency?

[yshui]

maybe the theme uses transparency?

I don't think that is the case. But you are encouraged to try.

This will be much easier if I can reproduce this bug, but now I guess I will have to add more debug prints.

I am going to implement proper logging and stuff so future bug reporters won't need to go through this again.

[ChrisLahaye]

Checked if I used any transparency which was not the case and changing themes also didn't work.

[yshui]

@ChrisLahaye I pumped the debug-30 branch with more debug messages. Please give it a run when you got time.

[ChrisLahaye]

@yshui

compton --config /dev/null --backend glx >output.log.txt 2>&1
output.log.txt

[yshui]

@ChrisLahaye Looks like your system has a non-working isnan() function. What libc do you use? Did you compile compton with -ffast-math or equivalent?

[yshui]

You can either remove things like -ffast-math or -Ofast from your CFLAGS, or you can try the current head of next. That should fix you problem.

[ChrisLahaye]

@yshui you are right, my compiler options enabled fast math, adding -fno-fast-math fixed it. How did you figure this out? Thanks a lot though I really appreciate your efforts to help me and the work you are doing.

[yshui]

@ChrisLahaye So in the logs I see windows get opacity of nan even if I have !isnan guards in place. And that is usually related to -ffast-math.