Access Busyness state#

This guide addresses how to access the busy state.

Often an application will have longer running callbacks which are being processed on the server, to give users some indication that the server is busy you may therefore have some way of indicating that busy state. The pn.state.busy parameter indicates whether a callback is being actively processed and may be linked to some visual indicator.

Below we will create a little application to demonstrate this, we will create a button which executes some longer running task on click and then create an indicator function that displays 'I'm busy' when the pn.state.busy parameter is True and 'I'm idle' when it is not:

import time
import panel as pn
pn.extension() # for notebook

def processing(event):
    # Some longer running task
    time.sleep(1)

button = pn.widgets.Button(label='Click me!')
button.on_click(processing)

def indicator(busy):
    return "I'm busy" if busy else "I'm idle"

pn.Row(button, pn.bind(indicator, pn.state.param.busy)).servable()




This way we can create a global indicator for the busy state instead of modifying all our callbacks.




Sync a Boolean indicator with the busy state#


If you already have a BooleanIndicator such as BooleanStatus or LoadingSpinner, you can skip the manual pn.bind wiring and let pn.state.sync_busy update the indicator’s value directly:


import time
import panel as pn
pn.extension() # for notebook

def processing(event):
    time.sleep(1)

button = pn.widgets.Button(label='Click me!')
button.on_click(processing)

busy = pn.indicators.LoadingSpinner(value=False, size=30)
pn.state.sync_busy(busy)

pn.Row(button, busy).servable()








sync_busy accepts any indicator whose value parameter is Boolean, and keeps multiple synced indicators in step with pn.state.busy.






Relate Resources#