Better progress indicators (feature request & design discussion)

[mike-lawrence]

At present, progress is indicated by simply printing the stdout of cmdstan, which is somewhat difficult to parse visually and spams the console with lots of lines.

Better would be a one-line-per-chain format with some indication of the progress on that chain as well as some timing information (estimate time left, with time elapsed being common and on it's own line) and where the line content is overwritten rather than advancing to new lines. I've actually implemented this but ended up having a lot of difficulty getting things to be guaranteed to look pretty across UIs, mostly related to the various UIs not reporting their console widths (or changes thereto) accurately. An alternative that I've also implemented is to put all info on one line (getting rid of space-taking progress bars) and that works but I find it a bit less aesthetically appealing. Similarly, if we used the jobs feature in RStudio, that would come with progress indicators but they would be limited in how much info they could include.

It think we might want a solution that could acommodate even more info (i.e. if the during-sampling diagnostics FR is implemented), so I wonder if something using html (shiny?) might make sense?

[bwiernik]

The progress package presents a progress bar that overwrites itself in the console versus filling up the lines. You might be able to import or even just take some code to smooth over your display.

[mike-lawrence]

@bwiernik thanks for your interest. I've actually looked at progress (and progressr, and others) and none implement the kind of multiple-progress-bars (one for each chain) display that we need for cmdstanr. But this does remind me that I should dive into their source to see if they've solved things more robustly than I have.

[mike-lawrence]

(Posting mostly as a accountability self-hack) FYI all I'm working on this today, so if anyone has had some updated opinions on progress indicators, chime in quick!

[mike-lawrence]

Going to to a "concise" version first, where it is just one line:

1: 100% | 2:  10% | 3:   1% | 4: ...  | 10m53s

Where the ... indicates a chain not yet started sampling and the time value at the end indicates the estimated time remaining to finish all chains. I was thinking of changing the background of the %s to indicate whether it is still in the warmup phase or sampling phase.

[mike-lawrence]

Decided to take an incremental strategy for implementation/PRs. First up is #477 with just the %s. Next is the time at the end, then the multi-line with progress bars.

[jgabry]

Doing some old issue cleanup and I'm to close this since #18 is still open and similar and PR #1138 is in progress