auto_refresh=False is slower than auto_refresh=True

[akihironitta]

Question

• Is it a known "issue" that auto_refresh=False is slower than auto_refresh=True? If so,
• why is auto_refresh=False slower than auto_refresh=True?

(related to #1536)

Possible cause

Digging into the rich codebase has made me think that it's because, with auto_refresh=True, there's a dedicated thread updating the progress bar while, with auto_refresh=False, the main thread updates the progress bar.

Do you think my guess is right? or are there any factors that slows down speed?

To reproduce

Here's my script which should have same number of "updates" (i.e., an update should occurs 10 times per second) in both cases. It would be great if you could tell if it's (in)appropriate for benchmarking speed between auto_refresh=True|False fairly.

Click to expand: code and output

# adapted from https://github.com/Textualize/rich/issues/1536
import time
from rich.progress import Progress

lines = range(100)

for auto_refresh in [True, False]:
    t0 = time.monotonic()

    with Progress(auto_refresh=auto_refresh) as progress:
        task = progress.add_task(
            f"auto_refresh={auto_refresh}",
            visible=True,
            total=len(lines),
        )
        for i, line in enumerate(lines):
            time.sleep(0.1)
            progress.update(task, advance=1)
            if not auto_refresh:
                progress.refresh()

    t1 = time.monotonic()
    print("time:", t1 - t0)

auto_refresh=True ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 100% 0:00:00
time: 10.464945208048448
auto_refresh=False ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 100% 0:00:00
time: 10.75676379201468

Click to expand: platform

 python -m rich.diagnose
╭───────────────────────── <class 'rich.console.Console'> ─────────────────────────╮
│ A high level console interface.                                                  │
│                                                                                  │
│ ╭──────────────────────────────────────────────────────────────────────────────╮ │
│ │ <console width=255 ColorSystem.TRUECOLOR>                                    │ │
│ ╰──────────────────────────────────────────────────────────────────────────────╯ │
│                                                                                  │
│     color_system = 'truecolor'                                                   │
│         encoding = 'utf-8'                                                       │
│             file = <_io.TextIOWrapper name='<stdout>' mode='w' encoding='utf-8'> │
│           height = 68                                                            │
│    is_alt_screen = False                                                         │
│ is_dumb_terminal = False                                                         │
│   is_interactive = True                                                          │
│       is_jupyter = False                                                         │
│      is_terminal = True                                                          │
│   legacy_windows = False                                                         │
│         no_color = False                                                         │
│          options = ConsoleOptions(                                               │
│                        size=ConsoleDimensions(width=255, height=68),             │
│                        legacy_windows=False,                                     │
│                        min_width=1,                                              │
│                        max_width=255,                                            │
│                        is_terminal=True,                                         │
│                        encoding='utf-8',                                         │
│                        max_height=68,                                            │
│                        justify=None,                                             │
│                        overflow=None,                                            │
│                        no_wrap=False,                                            │
│                        highlight=None,                                           │
│                        markup=None,                                              │
│                        height=None                                               │
│                    )                                                             │
│            quiet = False                                                         │
│           record = False                                                         │
│         safe_box = True                                                          │
│             size = ConsoleDimensions(width=255, height=68)                       │
│        soft_wrap = False                                                         │
│           stderr = False                                                         │
│            style = None                                                          │
│         tab_size = 8                                                             │
│            width = 255                                                           │
╰──────────────────────────────────────────────────────────────────────────────────╯
╭─── <class 'rich._windows.WindowsConsoleFeatures'> ────╮
│ Windows features available.                           │
│                                                       │
│ ╭───────────────────────────────────────────────────╮ │
│ │ WindowsConsoleFeatures(vt=False, truecolor=False) │ │
│ ╰───────────────────────────────────────────────────╯ │
│                                                       │
│ truecolor = False                                     │
│        vt = False                                     │
╰───────────────────────────────────────────────────────╯
╭─────────────────────────────────────────────────────────────────────────────────────────────────────────────────── Environment Variables ───────────────────────────────────────────────────────────────────────────────────────────────────────────────────╮
│ {                                                                                                                                                                                                                                                           │
│     'TERM': 'xterm-256color',                                                                                                                                                                                                                               │
│     'COLORTERM': 'truecolor',                                                                                                                                                                                                                               │
│     'CLICOLOR': None,                                                                                                                                                                                                                                       │
│     'NO_COLOR': None,                                                                                                                                                                                                                                       │
│     'TERM_PROGRAM': 'iTerm.app',                                                                                                                                                                                                                            │
│     'COLUMNS': None,                                                                                                                                                                                                                                        │
│     'LINES': None,                                                                                                                                                                                                                                          │
│     'JUPYTER_COLUMNS': None,                                                                                                                                                                                                                                │
│     'JUPYTER_LINES': None,                                                                                                                                                                                                                                  │
│     'JPY_PARENT_PID': None,                                                                                                                                                                                                                                 │
│     'VSCODE_VERBOSE_LOGGING': None                                                                                                                                                                                                                          │
│ }                                                                                                                                                                                                                                                           │
╰─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╯
platform="Darwin"
❯ pip freeze | grep rich
rich==12.5.1

Background

We're trying to debug slowdown in rich integration in our project (Lightning-AI/pytorch-lightning#13937), and git bisecting has led me to one of the changes made to the rich integration component (Lightning-AI/pytorch-lightning@137b62d).

---

P.S. Thank you for your wonderful work on this project!

[willmcgugan]

Auto refresh will perform a refresh 10 times a second no matter the workload, which will have a minimal impact on performance. If you don't use auto refresh and/or call refresh manually then you risk spending too much time rendering progress bars if you call it many times a second.

Your example code isn't the best at benchmarking, since sleeps aren't accurate. Try removing the sleep and changing the range to a million.

In general, there are few reasons to disable auto refresh.

[akihironitta]

then you risk spending too much time rendering progress bars if you call it many times a second.

I understand that calling refresh() many times per second will cause slowdown with auto_refresh=False, but would you say that auto_refresh=True would always (or generally) be faster than False if I managed to have the exact same number of updates per second in both cases?

Your example code isn't the best at benchmarking, since sleeps aren't accurate. Try removing the sleep and changing the range to a million.

Thank you for pointing it out. I see that my script isn't accurate at all, but removing the sleep and changing it to a very large number will call refresh() too many times per second with auto_refresh=False compared to 10 times per second with auto_refresh=True, so wouldn't it still be an unfair benchmark, would it?

In general, there are few reasons to disable auto refresh.

Because progress bars get updated async within another thread, which (in most cases) faster than manual refresh, correct? I'll explore how we could get it back to True again.

---

@willmcgugan Thank you very much for taking your time.