TaskGroupProgress stresses the scheduler

[mrocklin]

I'm seeing 70% usage, targetting this line:

                line_renderer = self.root.line(
                    x="time",
                    y=stack(*stackers[: i + 1]),
                    color=color,
                    alpha=1.0,
                    source=self.source,
                )

cc @ian-r-rose

[ian-r-rose]

Thanks for the report -- I'm not entirely surprised, since this draws a lot of fairly detailed glyphs. The good news is that this component only registers things on first open, so whatever performance hit might happen isn't incurred without the plot active.

I'm a little surprised that it's targeting just the line glyphs, since we're drawing both lines and areas in a very similar manner: https://github.com/dask/distributed/blob/34042bef503eac9c4794f3941c6554e3457521ed/distributed/dashboard/components/scheduler.py#L3044-L3062

I'll poke at it to see if anything obvious falls out. Edit: looking at it again, I do see some opportunities for doing a bit less work, but it would still involve drawing the same glyphs, so I'm unsure how much of an improvement it would make.