quiv 0.3.3

Quiv: threadpool-backed scheduler for Python applications

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quiv is a lightweight background task scheduler for Python applications.

It is designed to work especially well with FastAPI apps that need predictable, in-process background task orchestration.

Supports Python 3.10 through 3.14.

It provides:

• threadpool-backed execution
• support for sync and async task handlers
• cooperative cancellation (_stop_event)
• progress callbacks routed to your main async loop (_progress_hook)
• persistent task/job state via SQLModel + SQLite

When to use quiv

Use quiv when you need in-process background scheduling for app-level jobs, for example:

• polling APIs every N seconds
• periodic cleanup tasks
• one-shot delayed jobs
• progress-aware long-running workloads

Install

uv add quiv
# or
pip install quiv

Quick start

from contextlib import asynccontextmanager

from fastapi import FastAPI

from quiv import Quiv

scheduler = Quiv(timezone="UTC")


def ping(_progress_hook=None):
    for i in range(30):
        # do some work
        if _progress_hook:
            _progress_hook(message="ping", progress=i, total=30)


async def on_progress(**payload):
    # Replace with websocket broadcast, logging, metrics, etc.
    print("progress", payload)


@asynccontextmanager
async def lifespan(app: FastAPI):
    # Startup
    scheduler.start()
    yield
    # Shutdown
    scheduler.shutdown()


app = FastAPI(lifespan=lifespan)

@app.post("/start-heartbeat")
def start_heartbeat():
    scheduler.add_task(
        task_name="heartbeat",
        func=ping,
        interval=30,
        progress_callback=on_progress,
    )
    return {"message": "Heartbeat started successfully!"}

Documentation

Full documentation is available at nandyalu.github.io/quiv.

• Getting Started
• Bigger Applications
• API Reference
• Architecture
• Progress Callbacks
• Cancellation
• Exceptions

License

MIT