Python Concurrency and Multithreading
What is Concurrency and Multithreading in Python?
Concurrency and multithreading in Python contain the execution of more than one responsibilities concurrently, improving performance and responsiveness.
Two normally used modules for concurrent programming are threading for multithreading and asyncio for asynchronous programming.
Threading (Multithreading):
Threading module offers a manner to create and work with threads, allowing builders to implement multithreading of their applications.
Python's Global Interpreter Lock (GIL) limits the execution of a couple of threads in a unmarried technique, but threading is still beneficial for positive forms of duties, together with I/O-sure operations. For CPU-certain duties, multiprocessing is probably a more appropriate alternative.
Creating Threads:
You can create a thread by subclassing the threading.Thread elegance and imposing the run method.
import threading
import time
# Define a function that will be executed by each thread
def thread_function(name):
for _ in range(5):
print(f"Thread {name} is running")
time.sleep(1)
# Create two thread objects
thread1 = threading.Thread(target=thread_function, args=("Thread 1",))
thread2 = threading.Thread(target=thread_function, args=("Thread 2",))
# Start the threads
thread1.start()
thread2.start()
# Wait for both threads to finish
thread1.join()
thread2.join()
print("Main thread is done")
Basic Threading Example:
import threading
import time
def print_numbers():
for i in range(5):
time.sleep(1)
print(i)
def print_letters():
for letter in 'ABCDE':
time.sleep(1)
print(letter)
# Create threads
thread1 = threading.Thread(target=print_numbers)
thread2 = threading.Thread(target=print_letters)
# Start threads
thread1.start()
thread2.start()
# Wait for both threads to finish
thread1.join()
thread2.join()
print("Both threads have finished.")
In this case, print_numbers and print_letters are two features executed by separate threads.
Asyncio (Asynchronous Programming):
Asynchronous programming is a programming paradigm that permits a couple of obligations to be completed simultaneously, with out blocking off the execution of the principle application.
Python provides an asynchronous programming framework referred to as asyncio, which is part of the same old library beginning from Python three.Four. Asyncio is specifically useful for dealing with I/O-certain and excessive-concurrency eventualities.
Basic Asyncio Example:
import asyncio
async def print_numbers():
for i in range(5):
await asyncio.sleep(1)
print(i)
async def print_letters():
for letter in 'ABCDE':
await asyncio.sleep(1)
print(letter)
# Create an event loop
loop = asyncio.get_event_loop()
# Run coroutines concurrently
loop.run_until_complete(asyncio.gather(print_numbers(), print_letters()))
print("Both coroutines have finished.")
In this case, print_numbers and print_letters are two asynchronous coroutines carried out concurrently the usage of asyncio.Accumulate.
Threading vs. Asyncio:
- Threads run in parallel however may be constrained by way of the Global Interpreter Lock (GIL) in CPython.
- Useful for I/O-sure duties (e.G., community operations, document I/O).
- Multiple threads can run concurrently, however they will no longer take full benefit of more than one CPU cores due to the GIL.
Asyncio:
- Asynchronous programming is suitable for I/O-sure and excessive-stage structured community code.
- It is nicely-suitable for coping with many simultaneous connections effectively.
- Asyncio uses an event loop to control asynchronous responsibilities and coroutines.
Combining Threading and Asyncio:
It's feasible to apply threading for CPU-sure duties and asyncio for I/O-certain responsibilities to achieve concurrency and parallelism. However, be cautious approximately capacity issues with the GIL.
These examples provide a basic advent to concurrency and multithreading in Python.
Choose the technique that excellent suits your unique use case, thinking about factors like CPU-certain or I/O-sure obligations and the nature of your utility.