--show-progress=running polish

[sunshowers]

While trying out --show-progress=running and --show-progress=only, I noticed a few places where we could be more polished:

• As progress bars are added or removed, the main progress bar shifts up and down. This is more pronounced with --show-progress=running.
• There's a bunch of flickering which we should try to avoid.

I think for a polished experience indicatif's model is probably not complete enough, and we'd need to switch to using ratatui's inline viewport. There are a few things to handle:

• the viewport height should be set to the number of test threads
• we do some careful poking around terminal handling (see https://nexte.st/docs/design/architecture/input-handling/) -- we'll want to probably move terminal handling into its own module that both input and progress handling report to
• we can't use any of the ratatui init functions directly, since they'll enable terminal raw mode which we don't want. Instead, we'll have to figure out the correct termios options ourselves depending on which combination of input handling and the progress bar is enabled.

[sunshowers]

cc @glehmann if you'd like to tackle any of the above -- I think the current running implementation is good for a first pass but not quite to the polish level of the rest of the UI

[sunshowers]

Started working on this in #2721. Don't have the time to continue on this at the moment but definitely would like to get this fixed soon.

[sunshowers]

Ah -- ratatui is probably not feasible until ratatui/ratatui#1426 happens -- would definitely not want to lose overlong lines as currently output by nextest. Looking at other options.

[glehmann]

I agree, this is not as clean as I'd like. I'd like to add to the list of problems:

• the missing test lines with short-lived tests, which make the user think that there are not as many tests running as there should be (Add the 'running' progress mode #2676 (comment)).

Note that the movement of the main progress bar is probably more pronounced because of it.

I haven't yet looked at ratatui, and it may well be a better option. On the indicatif side, I think we can do better by not deleting the test bar when a test ends, but instead replacing it with an empty bar.

[sunshowers]

Yeah, here's my PR replacing it with an empty bar. Would love to get your eyes on it: #2723

[sunshowers]

#2722 was also crucial -- having the Tokio executor generate ticks instead of every progress bar doing its own thing -- means that all progress bar updates happen at the same time.

[glehmann]

#2722 was also crucial -- having the Tokio executor generate ticks instead of every progress bar doing its own thing -- means that all progress bar updates happen at the same time.

Nice, I thought of implementing that in indicatif's MultiProgress, but I wanted to make sure it would be accepted first.
You're moving too fast for me :)

[glehmann]

MultiProgress is not working as I thought it would: I thought the stderr_with_hz(20) would allow the entire progress bar to be rendered up to 20 times per second.

If MultiProgress were respecting the limit rate, it would be possible to update the progress bar configuration very often—200 times per second for example—but still get an actual redraw 20 times per second. That would have dropped the display of the fastest tests, but that's what is done since #2709 anyway, so that's not a problem.

That would also allow pushing all the tests to the progress bars, as it was done before #2709, and avoid the problem of too few tests being displayed.

Perhaps there is something in the code that causes the progress bars to be rendered too often…

[sunshowers]

Huh, wonder if the 20hz applies to every single progress bar independently.

[sunshowers]

In #2726 I reduced the refresh rate to 10hz which seems to be a nice improvement.

[sunshowers]

#2727 makes it so that we don't display more than 8 tests at a time by default, and adds an overflow bar. While testing this out with various --test-threads settings I noticed that some terminals would struggle to keep up with more than 8 or so progress bars updated at the same time.