Async Python Patterns
asyncio and async/await patterns for Python applications.
Quick Start
import asyncio
async def main():
print("Hello")
await asyncio.sleep(1)
print("World")
asyncio.run(main())When To Use
- Building async web APIs (FastAPI, aiohttp)
- Implementing concurrent I/O operations
- Creating web scrapers with concurrent requests
- Developing real-time applications (WebSockets)
- Processing multiple independent tasks simultaneously
- Building microservices with async communication
When NOT To Use
- CPU-bound optimization - use python-performance instead
- Testing async code - use python-testing async module
Modules
This skill uses progressive loading. Content is organized into focused modules:
- See
modules/basic-patterns.md- Core async/await, gather(), and task management - See
modules/concurrency-control.md- Semaphores and locks for rate limiting - See
modules/error-handling-timeouts.md- Error handling, timeouts, and cancellation - See
modules/advanced-patterns.md- Context managers, iterators, producer-consumer - See
modules/testing-async.md- Testing with pytest-asyncio - See
modules/real-world-applications.md- Web scraping and database operations - See
modules/pitfalls-best-practices.md- Common mistakes and best practices
Load specific modules based on your needs, or reference all for detailed guidance.
Exit Criteria
- Async patterns applied correctly
- No blocking operations in async code
- Proper error handling implemented
- Rate limiting configured where needed
- Tests pass with pytest-asyncio
Troubleshooting
Common Issues
RuntimeError: no current event loop Use asyncio.run() as the entry point. Avoid get_event_loop() in Python 3.10+.
Blocking call in async context Move sync I/O to asyncio.to_thread() or loop.run_in_executor().
Tests hang indefinitely Ensure pytest-asyncio is installed and test functions are decorated with @pytest.mark.asyncio.