ui: remove multi threaded prefix before each progress bar

[shcheklein]

When you run even a simple dvc pull for a single dvc file for a project that has only one data file it still shows the Multi threaded prefix before the progress bar.

git clone https://github.com/iterative/example-get-started
cd example-get-started
dvc pull

outputs some like:

Multi-Threaded:
 17%|█▋        |data/prepared/train.ts...

Commands like dvc pull, dvc push, etc are affected. I would expect to see something meaningful instead: Downloading files (multiple threads) or even w/o multiple threads.

Sometimes this Multi-Threaded: is blinking and replacing the progress bar itself which makes experience even worse.

[harsh8398]

@shcheklein you just want different static message right? or want some conditional message?

[kurianbenoy]

I would like to work on this, I am curious what is causing this Multi-Threaded message to come though?

[shcheklein]

@harsh8398 it's better to have a conditional message - that describes what is happening depending on the command.

We def should remove the blinking behavior.

@kurianbenoy feel free! but please coordinate with @harsh8398 if needed and please ask an advice with @casperdcl - an expert in TQDM :)

[casperdcl]

dvc/dvc/progress.py

Line 23 in a48481b

blank_bar = Tqdm(bar_format="Multi-Threaded:", leave=False)

but @shcheklein

Sometimes this Multi-Threaded: is blinking and replacing the progress bar itself which makes experience even worse.

shouldn't happen - is this still a thing after #2546?

[shcheklein]

@casperdcl I think it is still happening (on dvc pull). But I'll check again on the latest dev version.

[casperdcl]

I'm referring to specifically the blinking and overwriting. Shouldn't happen.

Anyway there has to at least be a temporary blank line (could replace "Multi-Threaded:" with an empty string) as that's by far the most painless way of letting tqdm know about being in multi-threaded mode.

[Suor]

Didn't get the last thing. Why tqdm can't be in multi-threaded mode without stating that with a message?

[casperdcl]

dvc/dvc/progress.py

Lines 20 to 21 in 877e385

	Creates a blank initial dummy progress bar if needed so that workers
	are forced to create "nested" bars.

I think the main idea is https://github.com/tqdm/tqdm/blob/91494ccf363e5eeb4745db7dbab70ef73c4a6eb0/tqdm/std.py#L1240 but due to

dvc/dvc/progress.py

Line 56 in 877e385

leave=False,

it might not be an issue any more.

Ah wait yes of course - it we assume all threads have leave=False then it's safe to remove the message. Otherwise they may wind up printing out of order.

[kurianbenoy]

So @casperdcl will it be possible to write conditional messages for each command as @shcheklein said?

[casperdcl]

I think missing conditional messages/verbosity is unrelated to the "remove unhelpful multi-threading message" issue. The first is a long term goal involving carefully relooking at each commamnd. The latter could probably be fixed by just removing the fake bar altogether...