python 线程池实用总结

线程池的两张方法 submit 和map

from concurrent.futures import ThreadPoolExecutor
import time

#


def sayhello(a):
    time.sleep(2)
    return "hello: "+a


def main():
    seed = ["a","b","c"]
    # 不使用线程
    start1 = time.time()
    for each in seed:
        t1 = sayhello(each)
        print(t1)
    end1 = time.time()
    print("time1: "+str(end1-start1))
    print('------------------submit----------------------')
    # 线程池submit用法
    # 1.先把值存放在列表中
    # 2.在遍历列表取返回值
    # 3.将遍历获取的结果存放在列表中
    start2 = time.time()
    lst = []
    result_lst = []
    with ThreadPoolExecutor(3) as executor:
        for each in seed:
            t2 = executor.submit(sayhello, each)
            lst.append(t2)
        for i in lst:
            print(i.result())
            result_lst.append(i.result())
        print(result_lst)
    end2 = time.time()
    print("time2: "+str(end2-start2))

    print('---------------map----------------------')
    # 线程池map的用法
    # map的参数：迭代器
    # map的返回值是：生成器
    # 1、获取生成器(或直接使用list强制装换)
    # 2、遍历取值
    # 3、将遍历的结果放入新的列表
    map_lst = []
    start3 = time.time()
    with ThreadPoolExecutor(3) as executor1:
        t3 = executor1.map(sayhello, seed)
        for t in t3:
            map_lst.append(t)
        print(map_lst)
    end3 = time.time()
    print("time3: "+str(end3-start3))


if __name__ == '__main__':
    main()

other

from concurrent.futures import ThreadPoolExecutor
import time

#


def sayhello(a):
    time.sleep(2)
    foo = [1, a]
    return foo


def main():
    seed = ["a","b","c"]
    # 不使用线程
    start1 = time.time()
    for each in seed:
        t1 = sayhello(each)
        print(t1)
    end1 = time.time()
    print("time1: "+str(end1-start1))

    print('---------------map----------------------')
    # 线程池map的用法
    # map 的结果是迭代器，使用for循环取值
    map_lst = []
    start3 = time.time()
    with ThreadPoolExecutor(3) as executor1:
        t3 = executor1.map(sayhello, seed)
        for t in t3:
            map_lst.extend(t)
        print(map_lst)
    end3 = time.time()
    print("time3: "+str(end3-start3))


if __name__ == '__main__':
    main()

区别

map:
1、提交的任务的函数是一样的
2、参数：只需要提交一次目标函数，目标函数的参数放在一个迭代器(列表,字典)
submit:
1、提交的任务函数是不一样的，或者执行的过程之可能出现异常(使用map执行过程中发现问题会直接抛出错误)
2、参数：submit每次都需要提交一个目标函数和对应的参数

结果：
map可以保证输出的顺序, submit输出的顺序是乱的