Introduction to Concurrency in Python
What is Concurrency?
Concurrency refers to the ability of a system to handle multiple tasks simultaneously. In the context of programming, it allows for efficient execution of code by enabling tasks to make progress without waiting for other tasks to complete.
Why Concurrency?
Utilizing concurrency can lead to:
- Improved performance for I/O-bound tasks
- Better resource utilization
- Increased responsiveness in applications
Threading in Python
Python's threading module allows for the creation of threads, enabling concurrent execution of code. Here's a simple example:
import threading
import time
def task():
print("Task started")
time.sleep(2)
print("Task completed")
thread = threading.Thread(target=task)
thread.start()
print("Thread started, main program continues...")
In this example, the main program continues to run while the thread executes the task in parallel.
Asyncio Module
The asyncio module provides a way to write asynchronous code using the async/await syntax. Below is an example:
import asyncio
async def main():
print("Main started")
await asyncio.sleep(2)
print("Main completed")
asyncio.run(main())
This code allows for non-blocking execution, making it ideal for I/O-bound tasks.
Best Practices for Concurrency
To effectively utilize concurrency in Python, consider the following best practices:
- Identify I/O-bound vs CPU-bound tasks.
- Use threading for I/O-bound tasks and multiprocessing for CPU-bound tasks.
- Leverage asyncio for handling multiple I/O operations.
- Be mindful of race conditions and use locks when necessary.
FAQ
What is the difference between concurrency and parallelism?
Concurrency is about dealing with multiple tasks at once, while parallelism is about doing multiple tasks at the same time.
When should I use threading over asyncio?
Use threading when working with I/O-bound tasks that require waiting, while asyncio is better for high-level structured network code.
Can I achieve true parallelism in Python?
True parallelism in Python can be achieved using the multiprocessing module, which creates separate processes, circumventing the Global Interpreter Lock (GIL).