Quickstart | Resonate Python SDK

The function you are about to activate

A countdown as a loop. Simple, but the function can run for minutes, hours, or days, despite restarts.

from resonate import Resonate, Context
from threading import Event

def countdown(ctx: Context, count: int, delay: int):
    for i in range(count, 0, -1):
        # Run a function, persist its result
        yield ctx.run(ntfy, i)
        # Sleep
        yield ctx.sleep(delay)
    print("Done!")


def ntfy(_: Context, i: int):
    print(f"Countdown: {i}")


# Instantiate Resonate
resonate = Resonate.remote()
# Register the function
resonate.register(countdown)
resonate.start() # Start Resonate threads
Event().wait()  # Keep the main thread alive

Steps to run

1. Install the Resonate Server & CLI

brew install resonatehq/tap/resonate

2. Install the Resonate SDK

pip install resonate-sdk

3. Start the server

resonate dev

4. Start the worker

python countdown.py

5. Activate the function

Activate the function with execution ID countdown.1:

resonate invoke countdown.1 --func countdown --arg 5 --arg 60

Result

You will see the countdown in the terminal

python countdown.py
Countdown: 5
Countdown: 4
Countdown: 3
Countdown: 2
Countdown: 1
Done!

What to try

After starting the function, inspect the current state of the execution using the resonate tree command. The tree command visualizes the call graph of the function execution as a graph of durable promises.

resonate tree countdown.1

Now try killing the worker mid-countdown and restarting. The countdown picks up right where it left off without missing a beat.

Next steps

• Learn how Resonate works
• Explore examples
• Build a real application