🐍 实战：多线程下载模拟

# ========================================
# 示例：多线程模拟下载
# 说明：3 个任务并行，总耗时约 max(各任务)
# ========================================
import threading
import time

def download(name, sec):
    print(name, '开始下载')
    time.sleep(sec)
    print(name, '下载完成', sec, '秒')

urls = [('文件A', 2), ('文件B', 1), ('文件C', 1.5)]
start = time.time()
threads = [threading.Thread(target=download, args=u) for u in urls]
for t in threads:
    t.start()
for t in threads:
    t.join()
print('总耗时', round(time.time() - start, 2), '秒')