This Gist extends the https://wave.h2o.ai/docs/examples/background/ example and shows that apps are still interactive while running background tasks.

wave_background_tests.py

import time
import random

from h2o_wave import main, app, Q, ui


def sleeper_agent(secs) -> str:
    time.sleep(secs)  # Blocks!
    return f'Done waiting for {secs} seconds!'


@app('/demo')
async def serve(q: Q):
    print(q.args)
    print(q.client)

    if q.args.start:
        await start_button_clicked(q)
    else:
        new_browser_tab(q)

    await q.page.save()


def new_browser_tab(q: Q):
    # Layout of the page
    q.page['meta'] = ui.meta_card(
        box='',
        layouts=[
            ui.layout(
                breakpoint='xs',
                width='1200px',
                zones=[
                    ui.zone('main_body', direction='column')
                ]
            )
        ]
    )
    # Home screen
    q.page['form'] = ui.form_card(
        box='main_body',
        items=[ui.button(name='start', label='Start')]
    )
    # Variable for this instance of the app
    q.client.event_count = 0


async def start_button_clicked(q: Q):

    count = q.client.event_count  # This function call uses this number
    q.client.event_count += 1  # Increment instantly in case another call is made while this runs

    q.page[f'event_card_{count}'] = ui.form_card(
        box='main_body',
        items=[ui.progress('Running...')]
    )
    await q.page.save()

    seconds = random.randint(1, 3)
    message = await q.run(sleeper_agent, seconds)

    q.page[f'event_card_{count}'] = ui.form_card(
        box='main_body',
        items=[ui.message_bar('info', message)]
    )