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Module 05: Synchronization Primitives

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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

Asyncio runs on a single thread, so many classic threading race conditions cannot occur. But concurrent coroutines can interleave at await points, and shared state is still possible to corrupt if not protected. This module covers asyncio's synchronization primitives — the async equivalents of threading locks, events, semaphores, and queues — and when to use each.

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 04: Async I/O Patterns
  • Module 03: Tasks and Futures

Objectives

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

  1. Identify when shared state needs protection in async code
  2. Use asyncio.Lock for mutual exclusion
  3. Use asyncio.Event to signal between coroutines
  4. Use asyncio.Semaphore to limit concurrency
  5. Use asyncio.Queue for producer-consumer patterns
  6. Implement a simple worker pool using Queue and create_task()

Theory

Full content to be generated. Topics to cover:

  • Why single-threaded asyncio still needs synchronization (the read-modify-await-write race)
  • asyncio.Lock: mutual exclusion, async with lock: pattern, deadlock risk
  • asyncio.Event: one-shot notifications, resetting, broadcasting to multiple waiters
  • asyncio.Condition: coordinating waiters with a condition predicate
  • asyncio.Semaphore and asyncio.BoundedSemaphore: limiting concurrency
  • asyncio.Queue, asyncio.LifoQueue, asyncio.PriorityQueue
  • Producer-consumer pattern with queue.put(), queue.get(), queue.join()
  • Worker pool pattern: fixed number of worker tasks draining a queue

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/04_async-io]] — prerequisite; async I/O patterns this module builds on
  • [[async-python/modules/06_structured-concurrency]] — structured concurrency provides a better alternative to manual task coordination in many cases
  • [[async-python/modules/07_performance-patterns]] — Semaphore-based rate limiting builds directly on this module

Summary

To be filled in when this module is fully generated.