Buffer 'docker stats' text to avoid terminal flickering #5586
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Additional details and impacted files@@ Coverage Diff @@
## master #5586 +/- ##
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- Coverage 59.64% 59.63% -0.02%
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Files 346 346
Lines 29207 29213 +6
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Hits 17421 17421
- Misses 10817 10823 +6
Partials 969 969 |
cli/command/container/stats.go
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| // Buffer to store formatted stats text. | ||
| // Once formatted, it will be printed in one write to avoid screen flickering. | ||
| var statsTextBuffer strings.Builder |
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I'd suggest using bytes.Buffer here instead, see my comment below
| var statsTextBuffer strings.Builder | |
| var statsTextBuffer bytes.Buffer |
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Thanks for a quick review! I've replaced strings.Builder with bytes.Buffer :) And yes, the "proper" solution for this would involve keeping track of the two "frames" and only redrawing the parts that have changed. But that would be a lot more involved than what we are doing now. Curious that you are still seeing the issue with kitty, since for me kitty worked well even before this change. I'm guessing it could be due to GPU drivers, and similar low level stuff, because AFAIK kitty uses GPU for text rendering. |
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I think kitty is just fast enough to output the characters on the screen as soon as they're read. This could probably be tweaked with kitty settings to decrease the output frequency. But yeah, the proper solution would be to double-buffer the output and only change the actual difference. However, this is definitely an improvement for most users :) |
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Thanks! Could you also squash the commits and make sure your commit has a DCO? |
done! |
This change reduces the flickering of the terminal when running `docker stats` by buffering the formatted stats text and printing it in one write. Should also consume less CPU as we now only have to issue a single syscall to write the stats text to the terminal. Signed-off-by: Giedrius Jonikas <[email protected]>
This change reduces the flickering of the terminal when running
docker statsby buffering the formatted stats text and printing it in one write.Should also consume less CPU as we now only have to issue a single syscall to write the stats text to the terminal.
I suspect it fixes #4348, but I can not confirm since that issue was reported on WSL.
- What I did
On all of my Linux machines (Fedora Linux + GNOME) I can see terminal flickering when running 'docker stats'.
I've tested this with gnome-terminal/xfce4-terminal/xterm and it flickers on all. The only term that does not flicker is kitty.
I've also tested this on GNOME running Wayland and X11. I can see no difference in behaviour between Wayland/X11.
I've tested this on two machines: Thinkpad T14s gen1 running AMD zen, and a desktop PC running AMD zen chip with Radeon GPU. Both behave identically.
recording of the flickering:
https://github.com/user-attachments/assets/05f8278e-05c3-411e-bb32-dad262136937
'docker stats' used to issue multiple write calls to stdout. Starting with the "clear screen" command and following multiple small write requests.
I'm now bundling all of those into a single string that is then written out to the stdout as a single request.
This fixes the flickering (as well as reduces syscalls required for each update) on both of my machines.
I've tested this on Fedora 41 GNOME with the following terminal emulators: gnome-terminal/xfce4-terminal/xterm/kitty.
I've tried things like resizing the window as 'docker stats' was running. It all works flawlessly now :)
- Description for the changelog
- A picture of a cute animal (not mandatory but encouraged)
A cat that sometimes roams outside my flat. Me and my flatmates call him Phantom 🐱