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Module 03: Tasks and Futures

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Stub module — Full content to be generated. This file defines the scope and prerequisites so the topic roadmap is complete.

Overview

Module 02 covered how the event loop runs coroutines. This module covers Tasks — the higher-level object that wraps a running coroutine and gives you handles to inspect, cancel, and wait for it. It also covers Futures — the low-level awaitable object that Tasks are built on — and the suite of concurrent execution utilities: asyncio.gather(), asyncio.wait(), and asyncio.wait_for().

By the end of this module, you will be able to write programs that orchestrate many concurrent operations with fine-grained control: start tasks, cancel specific ones, wait for the first to finish, and handle partial failures gracefully.

Table of Contents

  1. Overview
  2. Prerequisites
  3. Objectives
  4. Theory
  5. Key Concepts
  6. Examples
  7. Common Pitfalls
  8. Cross-Links
  9. Summary

Prerequisites

  • Module 02: Coroutines and the Event Loop
  • Module 01: Introduction to Async Python

Objectives

By the end of this module, you will be able to:

  1. Create and manage Tasks with asyncio.create_task()
  2. Use asyncio.gather() for fan-out concurrency with result collection
  3. Use asyncio.wait() for fine-grained wait control (FIRST_COMPLETED, ALL_COMPLETED)
  4. Apply asyncio.wait_for() and asyncio.timeout() for timeout handling
  5. Cancel tasks and handle asyncio.CancelledError correctly
  6. Understand the asyncio.Future API and when it is used directly

Theory

Full content to be generated. Topics to cover:

  • asyncio.create_task() vs. directly awaiting a coroutine
  • Task lifecycle: pending → running → cancelled / done (with result or exception)
  • asyncio.gather() — concurrent execution, return_exceptions, ordering guarantees
  • asyncio.wait() — FIRST_COMPLETED, FIRST_EXCEPTION, ALL_COMPLETED strategies
  • asyncio.wait_for() — timeout wrapping, cancellation behavior
  • asyncio.timeout() — context manager API (Python 3.11+)
  • Task cancellation: task.cancel(), CancelledError, cleanup patterns
  • asyncio.Future — the low-level awaitable; set_result(), set_exception()
  • asyncio.shield() — protecting a coroutine from cancellation

Key Concepts

To be filled in when this module is fully generated.

Examples

To be filled in when this module is fully generated.

Common Pitfalls

To be filled in when this module is fully generated.

  • [[async-python/modules/02_coroutines-and-event-loop]] — prerequisite
  • [[async-python/modules/05_synchronization]] — synchronization primitives complement task management
  • [[async-python/modules/06_structured-concurrency]] — TaskGroup builds on task/future concepts

Summary

To be filled in when this module is fully generated.