RuntimeError: "There is no current event loop" when running streamlit app with stpyvista

[mhamidasn]

I am encountering a RuntimeError when attempting to run a Streamlit app that utilizes stpyvista for visualization. I run the example stpyvista code, which is this one:

import streamlit as st
import pyvista as pv
from stpyvista import stpyvista

## Initialize a plotter object
plotter = pv.Plotter(window_size=[400,400])

## Create a mesh with a cube 
mesh = pv.Cube(center=(0,0,0))

## Add some scalar field associated to the mesh
mesh['myscalar'] = mesh.points[:, 2]*mesh.points[:, 0]

## Add mesh to the plotter
plotter.add_mesh(mesh, scalars='myscalar', cmap='bwr', line_width=1)

## Final touches
plotter.view_isometric()
plotter.add_scalar_bar()
plotter.background_color = 'white'

## Pass a key to avoid re-rendering at each time something changes in the page
stpyvista(plotter, key="pv_cube")

However, when I did run streamlit app.py, I encounter the following error:

RuntimeError: There is no current event loop in thread 'ScriptRunner.scriptThread'.
Traceback:
File "D:\Python\Python39\lib\site-packages\streamlit\runtime\scriptrunner\script_runner.py", line 535, in _run_script
    exec(code, module.__dict__)
File "C:\Users\hamid\Downloads\app.py", line 3, in <module>
    from stpyvista import stpyvista
File "D:\Python\Python39\lib\site-packages\stpyvista\__init__.py", line 8, in <module>
    import panel as pn
File "D:\Python\Python39\lib\site-packages\panel\__init__.py", line 50, in <module>
    from . import chat  # noqa
File "D:\Python\Python39\lib\site-packages\panel\chat\__init__.py", line 33, in <module>
    from .feed import ChatFeed  # noqa
File "D:\Python\Python39\lib\site-packages\panel\chat\feed.py", line 25, in <module>
    from ..io.resources import CDN_DIST
File "D:\Python\Python39\lib\site-packages\panel\io\__init__.py", line 9, in <module>
    from .document import (  # noqa
File "D:\Python\Python39\lib\site-packages\panel\io\document.py", line 47, in <module>
    WRITE_LOCK = asyncio.Lock()
File "D:\Python\Python39\lib\asyncio\locks.py", line 81, in __init__
    self._loop = events.get_event_loop()
File "D:\Python\Python39\lib\asyncio\events.py", line 642, in get_event_loop
    raise RuntimeError('There is no current event loop in thread %r.'

Any guidance on resolving this issue would be greatly appreciated :)

Additional Information:

• python version: 3.9.13
• pyvista version: 0.42.0
• Streamlit version: 1.30.0
• stpyvista version: 0.0.14

[edsaac]

What version of panel is installed in your environment?

[mhamidasn]

``The version of panel installed in my environment is 1.3.8.

However, after several attempts, I decided to downgrade the stpyvista version to see if it resolves the issue. After several downgrades, I found that the version that does not return any error is stpyvista version 0.0.11.

(+) after i add this to my code:

import asyncio

try:
    loop = asyncio.get_event_loop()
except RuntimeError as ex:
    if "There is no current event loop in thread" in str(ex):
        loop = asyncio.new_event_loop()
        asyncio.set_event_loop(loop)
    else:
        raise

[edsaac]

👍 I was able to replicate your issue only if running python 3.9. No exception is raised if running python 3.10 or 3.11. I'll check what exactly is going wrong...

[edsaac]

It seems this issue has been solved as the Runtime Error is not raised anymore with the latest version of panel.

Tested with:

• Python 3.9.18
• panel 1.4.0
• pyvista 0.43.4
• stpyvista 0.0.16

I'm closing this issue but feel free to reopen if I missed something.