Python：concurrent 库高级用法举例和应用详解

import concurrent.futures

import concurrent.futures # 导入concurrent.futures模块
import requests # 导入requests模块，用于HTTP请求

urls = [
    'http://www.example.com',
    'http://www.example.org',
    'http://www.example.net'
] # 定义要下载的URL列表

def fetch_url(url):
    """下载指定URL的内容"""
    response = requests.get(url) # 发送HTTP GET请求
    return response.text # 返回网页内容

# 使用ThreadPoolExecutor进行多线程下载
with concurrent.futures.ThreadPoolExecutor(max_workers=3) as executor:
    futures = {executor.submit(fetch_url, url): url for url in urls} # 提交任务
    for future in concurrent.futures.as_completed(futures):
        url = futures[future] # 获取对应的URL
        try:
            data = future.result() # 获取任务结果
            print(f"{url} downloaded successfully") # 打印成功消息
        except Exception as e:
            print(f"{url} generated an exception: {e}") # 打印异常消息

import concurrent.futures # 导入concurrent.futures模块
import math # 导入math模块，用于计算阶乘

numbers = [5, 10, 20, 30] # 定义要计算阶乘的数字列表

def factorial(n):
    """计算n的阶乘"""
    return math.factorial(n) # 返回n的阶乘

# 使用ProcessPoolExecutor进行多进程计算
with concurrent.futures.ProcessPoolExecutor(max_workers=4) as executor:
    results = list(executor.map(factorial, numbers)) # 并行计算阶乘
    for number, result in zip(numbers, results):
        print(f"Factorial of {number} is {result}") # 打印计算结果

import concurrent.futures # 导入concurrent.futures模块
import time # 导入time模块，用于模拟任务延迟

def task(n):
    """模拟任务处理"""
    time.sleep(n) # 模拟延迟
    return f"Task {n} completed" # 返回任务完成消息

tasks = [2, 3, 1, 4] # 定义任务列表，每个任务对应一个延迟秒数

# 使用ThreadPoolExecutor执行任务
with concurrent.futures.ThreadPoolExecutor(max_workers=4) as executor:
    futures = {executor.submit(task, task): task for task in tasks} # 提交任务
    for future in concurrent.futures.as_completed(futures):
        task = futures[future] # 获取任务信息
        try:
            result = future.result() # 获取任务结果
            print(result) # 打印任务完成消息
        except Exception as e:
            print(f"Task {task} generated an exception: {e}") # 打印异常消息