Accessing q:Q object in a wave app on startup

[n-srinidhi]

How to access the q:Q object in the 'on_startup' function while running a Wave App?
Basically, I am trying to create a background task, which will execute periodically to update the stats cards and other components in my Wave App. Like this:

logging.info('Starting background thread..')
    while True:
        with concurrent.futures.ThreadPoolExecutor() as pool:
            frame=await q.exec(pool, load_data)            
            print(frame)
            time.sleep(1)

when I try to attach this to @app('/'), It requires the q:Q object to be passed as an argument.

[mturoci]

The q object is only accesible when the client (browser) is connected - sends data to Wave app server. on_startup is a hook for when the Wave app server is booted up (no client connected yet).

Your 2 options in this case are:

• Start the background job in app/client init within the serve function.
• Start the background job in the on startup and pass the q object for subsequent updates afterwards - slightly more complex.