线程池 ThreadPoolExecutor

1.线程池的原理

2.使用线程池的好处

3.ThreadPoolExecutor的使用用法

4.使用线程池改造爬虫程序

    def do_task(n):
        if n > 5:
            print(n, '开始做任务')
            time.sleep(0.5)
            res = str(n) + '你真漂亮'
            return res
        else:
            print('没做任务')
    tasks = [7, 9, 10, 12]
    import concurrent.futures
    with concurrent.futures.ThreadPoolExecutor() as pool:
        strs = list(pool.map(do_task, tasks))
        for str2 in strs:
            print('map', str2)
    print('map over')
    with concurrent.futures.ThreadPoolExecutor() as pool:
        strs1 = [pool.submit(do_task, task) for task in tasks]
        for task in concurrent.futures.as_completed(strs1):
            print(task.result())
        print(strs)
    print('submit over')