Async Programming in Vuer

Overview

Vuer supports asynchronous programming patterns for handling parallel routines and callbacks. The tutorial demonstrates creating a server with background tasks running concurrently.

Key Components

Server Setup

The framework uses Vuer() to instantiate a server with configuration options via query parameters like reconnect=True and collapseMenu=True.

Main Function Decorator

The @app.spawn(start=True) decorator marks the entry point as an async function that starts the application immediately.

Task Management

Sessions provide spawn_task() method for launching background operations. Tasks can be cancelled with .cancel() when no longer needed.

Code Pattern Example

The tutorial shows a main loop that:

Spawns independent background tasks
Updates scene objects continuously using sess.upsert
Manages task lifecycle by cancelling long-running operations after conditions are met
Uses await sleep() for non-blocking delays

Complete Example

from vuer import Vuer
from vuer.schemas import Scene, Box
import asyncio
import numpy as np

app = Vuer(
    queries=dict(
        reconnect=True,
        collapseMenu=True,
    ),
)

async def background_task(session):
    """A background task that runs independently"""
    count = 0
    while True:
        print(f"Background task running: {count}")
        count += 1
        await asyncio.sleep(1.0)

@app.spawn(start=True)
async def main(session):
    # Spawn a background task
    task = session.spawn_task(background_task(session))

    # Main animation loop
    for i in range(100):
        theta = i * 0.1
        x = 0.5 * np.cos(theta)
        z = 0.5 * np.sin(theta)

        # Update the box position
        session.upsert @ Box(
            args=[0.1, 0.1, 0.1],
            position=[x, 0.05, z],
            color="red",
            materialType="standard",
            key="animated-box",
        )

        await asyncio.sleep(0.05)

    # Cancel the background task when done
    task.cancel()

app.run()

Practical Features

The demonstration animates a red box moving in a circular path while background tasks execute independently, illustrating how multiple asynchronous operations coexist within a single VuerSession without blocking the main rendering loop.

Best Practices

Use session.spawn_task() for background operations
Always use await asyncio.sleep() for delays to avoid blocking
Cancel tasks when they're no longer needed to free resources
Use session.upsert for updating scene components

Source

Documentation: https://docs.vuer.ai/en/latest/tutorials/basics/async_programming.html

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