[BUG] Console appears not to be a terminal in background thread

I’ve set up a widget with a spinner as renderable. I instantiate using Live(spinner_widget) and then call start() on the Live instance. However, the renderable doesn’t update, even though the thread is started and calls refresh() on the Live instance at intervals. It can be updated through e.g. an action, as per the code sample given below.

It appears that the proximate reason is that in this line https://github.com/Textualize/rich/blob/5f4e93efb159af99ed51f1fbfd8b793bb36448d9/rich/live.py#L238

self.console.is_terminal is returning False. That seems to be because in this line https://github.com/Textualize/rich/blob/5f4e93efb159af99ed51f1fbfd8b793bb36448d9/rich/console.py#L954

isatty is None when called in the live refresh thread.

In an attempt to understand what’s happening, I inserted some logging statements. Just after the start() call, I see this in the log:

__main__       22 MainThread <_RefreshThread(Thread-3, started daemon 140431866193664)>
rich.console  956 MainThread isatty: <bound method _WriterThread.isatty of <_WriterThread(Thread-1, started daemon 140431953118976)>>: True
rich.console  956 MainThread isatty: <bound method _WriterThread.isatty of <_WriterThread(Thread-1, started daemon 140431953118976)>>: True
rich.console  956 MainThread isatty: <bound method _WriterThread.isatty of <_WriterThread(Thread-1, started daemon 140431953118976)>>: True
... (more duplicate lines elided)
rich.console  956 MainThread isatty: <bound method _WriterThread.isatty of <_WriterThread(Thread-1, started daemon 140431953118976)>>: True
rich.console  956 Thread-3   isatty: None: False
rich.console  956 Thread-3   isatty: None: False
rich.live     223 Thread-3   Console: <console width=220 None> is terminal? False

Since in the thread the console appears to be what you’d expect, it’s not immediately clear why isatty would be None. This might be a misunderstanding on my part rather than an actual bug, but I think I followed the documentation to set things up and so expected it to work. Example Code The code I used:

import logging
import time

from rich.live import Live
from rich.spinner import Spinner
from textual.app import App, ComposeResult
from textual.widgets import Static, Footer

logger = logging.getLogger(__name__)

class SpinnerStatic(Static):
    def __init__(self, spinner, **kwargs):
        super().__init__(**kwargs)
        self.spinner = spinner
        self.live = Live(spinner)

    def on_mount(self):
        self.update(self.spinner)
        self.live.start()
        time.sleep(0.1)
        logger.debug(self.live._refresh_thread)

class TestApp(App):
    BINDINGS = [("r", "refresh", "Refresh")]

    def compose(self) -> ComposeResult:
        spinner = Spinner('moon', speed=1.0)
        w = SpinnerStatic(spinner, id='spinner')
        self.spinner = w
        yield w
        yield Footer()

    def action_refresh(self):
        self.spinner.refresh()

logging.basicConfig(level=logging.DEBUG,
                    filename='spinner.log',
                    filemode='w',
                    format='%(name)-12s %(lineno)4d %(threadName)-10s %(message)s')
app = TestApp()
app.run()

Platform

Click to expand

Linux (Ubuntu 64-bit), standard terminal

I may ask you to copy and paste the output of the following commands. It may save some time if you do it now.

If you’re using Rich in a terminal:

$ python -m rich.diagnose
╭───────────────────────── <class 'rich.console.Console'> ─────────────────────────╮
│ A high level console interface.                                                  │
│                                                                                  │
│ ╭──────────────────────────────────────────────────────────────────────────────╮ │
│ │ <console width=220 ColorSystem.TRUECOLOR>                                    │ │
│ ╰──────────────────────────────────────────────────────────────────────────────╯ │
│                                                                                  │
│     color_system = 'truecolor'                                                   │
│         encoding = 'utf-8'                                                       │
│             file = <_io.TextIOWrapper name='<stdout>' mode='w' encoding='utf-8'> │
│           height = 24                                                            │
│    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=220, height=24),             │
│                        legacy_windows=False,                                     │
│                        min_width=1,                                              │
│                        max_width=220,                                            │
│                        is_terminal=True,                                         │
│                        encoding='utf-8',                                         │
│                        max_height=24,                                            │
│                        justify=None,                                             │
│                        overflow=None,                                            │
│                        no_wrap=False,                                            │
│                        highlight=None,                                           │
│                        markup=None,                                              │
│                        height=None                                               │
│                    )                                                             │
│            quiet = False                                                         │
│           record = False                                                         │
│         safe_box = True                                                          │
│             size = ConsoleDimensions(width=220, height=24)                       │
│        soft_wrap = False                                                         │
│           stderr = False                                                         │
│            style = None                                                          │
│         tab_size = 8                                                             │
│            width = 220                                                           │
╰──────────────────────────────────────────────────────────────────────────────────╯
╭─── <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': None,          │
│     'COLUMNS': None,               │
│     'LINES': None,                 │
│     'JUPYTER_COLUMNS': None,       │
│     'JUPYTER_LINES': None,         │
│     'JPY_PARENT_PID': None,        │
│     'VSCODE_VERBOSE_LOGGING': None │
│ }                                  │
╰────────────────────────────────────╯
platform="Linux"
$ pip freeze | grep rich
rich==12.6.0

[willmcgugan]

I think we will have builtin widgets for spinner / progress eventually. So probably not worth adding those to docs right now.

However, it would make an excellent blog post!

[willmcgugan]

Textual uses asyncio which is generally single threaded. So your thread approach is unlikely to work. Fortunately it is generally easier to implement such things with timers, as Rodrigo’s examples shows!