Python Concurrency, Asyncio, Flask Web Development, SQLite, and Git Basics

Concurrency programming is a vital part of modern software development, and Python offers several models such as multithreading, multiprocessing, and asynchronous programming with asyncio .

Multithreading (threading module) allows multiple tasks to run simultaneously within a single program, improving efficiency. Example code:

# 导入 threading 模块：
import threading

# 定义线程：
def worker():
    print(threading.current_thread().name, "Starting")
    # Your code here
    print(threading.current_thread().name, "Exiting")

thread1 = threading.Thread(target=worker)
thread2 = threading.Thread(target=worker)
thread1.start()
thread2.start()
thread1.join()
thread2.join()

# 传递参数：
def worker(name):
    print(threading.current_thread().name, "Starting", name)
    # Your code here
    print(threading.current_thread().name, "Exiting", name)

thread1 = threading.Thread(target=worker, args=("Thread 1",))
thread2 = threading.Thread(target=worker, args=("Thread 2",))
thread1.start()
thread2.start()
thread1.join()
thread2.join()

# 线程同步：
lock = threading.Lock()

def worker(name):
    with lock:
        print(threading.current_thread().name, "Starting", name)
        # Your code here
        print(threading.current_thread().name, "Exiting", name)

thread1 = threading.Thread(target=worker, args=("Thread 1",))
thread2 = threading.Thread(target=worker, args=("Thread 2",))
thread1.start()
thread2.start()
thread1.join()
thread2.join()

Multiprocessing (multiprocessing module) runs tasks in parallel across multiple CPU cores, boosting computational power. Example code:

# 导入 multiprocessing 模块：
import multiprocessing

# 定义进程：
def worker():
    print(multiprocessing.current_process().name, "Starting")
    # Your code here
    print(multiprocessing.current_process().name, "Exiting")

process1 = multiprocessing.Process(target=worker)
process2 = multiprocessing.Process(target=worker)
process1.start()
process2.start()
process1.join()
process2.join()

# 传递参数：
def worker(name):
    print(multiprocessing.current_process().name, "Starting", name)
    # Your code here
    print(multiprocessing.current_process().name, "Exiting", name)

process1 = multiprocessing.Process(target=worker, args=("Process 1",))
process2 = multiprocessing.Process(target=worker, args=("Process 2",))
process1.start()
process2.start()
process1.join()
process2.join()

Asynchronous programming (asyncio module) enables non‑blocking execution of tasks, improving responsiveness. Example code:

# 导入 asyncio 模块
import asyncio

# 定义异步函数
async def fetch_data(url):
    print("Fetching data from", url)
    await asyncio.sleep(1)  # 模拟网络延迟
    print("Data fetched from", url)

async def main():
    task1 = asyncio.create_task(fetch_data("http://example.com"))
    task2 = asyncio.create_task(fetch_data("http://example.org"))
    await task1
    await task2

asyncio.run(main())

# 并发执行多个任务
async def main():
    urls = ["http://example.com", "http://example.org", "http://example.net"]
    tasks = [fetch_data(url) for url in urls]
    await asyncio.gather(*tasks)

asyncio.run(main())

Web development basics (Flask framework) – Flask is a lightweight Python web framework suitable for beginners. Install it and create a simple web app with routes and form handling. Example code:

# 安装 Flask
pip install Flask

# 定义路由：
from flask import Flask, request
app = Flask(__name__)

@app.route('/')
def home():
    return "Welcome to the home page!"

@app.route('/about')
def about():
    return "This is the about page."

if __name__ == '__main__':
    app.run(debug=True)

# 处理表单数据：
@app.route('/login', methods=['GET', 'POST'])
def login():
    if request.method == 'POST':
        username = request.form['username']
        password = request.form['password']
        return f"Username: {username}, Password: {password}"
    return '''
Username:
Password:
'''

if __name__ == '__main__':
    app.run(debug=True)

Database operations (sqlite3 module) – SQLite is a lightweight, file‑based database useful for automation testing. Example code demonstrates creating a database, a table, inserting, querying, and closing the connection.

# 导入 sqlite3 模块
import sqlite3

# 连接数据库：
conn = sqlite3.connect('example.db')
cursor = conn.cursor()

# 创建表：
cursor.execute('''
    CREATE TABLE IF NOT EXISTS users (
        id INTEGER PRIMARY KEY,
        name TEXT NOT NULL,
        email TEXT NOT NULL UNIQUE
    )
''')
conn.commit()

# 插入数据：
cursor.execute('''
    INSERT INTO users (name, email) VALUES (?, ?)
''', ('Alice', '[email protected]'))
conn.commit()

# 查询数据：
cursor.execute('SELECT * FROM users WHERE name = ?', ('Alice',))
rows = cursor.fetchall()
for row in rows:
    print(row)

# 关闭连接：
conn.close()

Version control (Git) – Git is an essential tool for software development. The article covers installation on various platforms, repository initialization, adding and committing files, checking status, cloning remote repositories, and pushing/pulling changes. Example commands:

# Ubuntu/Debian
sudo apt-get install git
# macOS (Homebrew)
brew install git
# Windows – download from https://git-scm.com/download/win

# 初始化仓库
mkdir my_project
cd my_project
git init

# 添加和提交文件
touch example.py
git add example.py
git commit -m "Initial commit"

# 查看状态
git status

# 克隆远程仓库
git clone https://github.com/username/repo.git

# 推送和拉取代码
git push origin main
git pull origin main