Python多线程编程的核心概念与实践方法

import threading
import time

def task(name, seconds):
    print(f"线程 {name} 开始执行")
    time.sleep(seconds)
    print(f"线程 {name} 执行完毕")

# 创建线程
t1 = threading.Thread(target=task, args=("A", 2))
t2 = threading.Thread(target=task, args=("B", 1))

# 启动线程
t1.start()
t2.start()

# 等待线程结束
t1.join()
t2.join()

print("所有线程执行完毕")

import threading
import time

class MyThread(threading.Thread):
    def __init__(self, name):
        super().__init__()
        self.name = name
    
    def run(self):
        print(f"线程 {self.name} 开始")
        time.sleep(2)
        print(f"线程 {self.name} 结束")

t = MyThread("自定义线程")
t.start()
t.join()

import threading

balance = 0
lock = threading.Lock()

def deposit():
    global balance
    for _ in range(100000):
        lock.acquire()  # 加锁
        try:
            balance += 1
        finally:
            lock.release()  # 解锁

t1 = threading.Thread(target=deposit)
t2 = threading.Thread(target=deposit)

t1.start()
t2.start()
t1.join()
t2.join()

print(f"最终余额: {balance}")  # 正确输出 200000

# 去掉 lock，结果可能是 199847（数据不一致）

from concurrent.futures import ThreadPoolExecutor
import time

def task(n):
    print(f"任务 {n} 开始")
    time.sleep(1)
    return f"任务 {n} 完成"

# 创建线程池（最多5个线程）
with ThreadPoolExecutor(max_workers=5) as executor:
    # 提交10个任务
    futures = [executor.submit(task, i) for i in range(10)]
    
    # 获取结果
    for future in futures:
        print(future.result())

import threading
import requests
from concurrent.futures import ThreadPoolExecutor

def download_image(url):
    try:
        response = requests.get(url, timeout=10)
        filename = url.split("/")[-1]
        with open(filename, "wb") as f:
            f.write(response.content)
        print(f"✅ 下载完成: {filename}")
    except Exception as e:
        print(f"❌ 下载失败: {url}, 错误: {e}")

urls = [
    "https://example.com/image1.jpg",
    "https://example.com/image2.jpg",
    "https://example.com/image3.jpg",
]

# 使用线程池并发下载
with ThreadPoolExecutor(max_workers=3) as executor:
    executor.map(download_image, urls)