如何用"for"循环多线程？

Question

之前可能已经问了几次类似的问题,但是它们似乎都没有我的案例/场景或它不起作用.

我试图多线程一个for循环,如一个例子中所示.这个for循环将在循环数组时执行一个函数.我想多线程.

例:

array = ["a", "b", "c", "d", "e"]
def dosomething(var):
    #dosomething this is just an example as my actual code is not relevant to this question

for arrayval in array:
    dosomething(arrayval)

这应该通过数组循环并执行功能dosomething与变量a,那么b,c等等.

关于我怎么做的任何想法？

Answer 1

您可以使用threading.Thread：

from threading import Thread
from time import sleep
from random import randint

def dosomething(var):
    sleep(randint(1,5))
    print(var)

array = ["a", "b", "c", "d", "e"]
threads = []
for arrayval in array:
    threads.append(Thread(target=dosomething, args=(arrayval,)))
    threads[-1].start()
for thread in threads:
    thread.join()

5 秒内以随机顺序输出：

e
b
c
a
d

如果你想限制线程数，你可以使用multiprocessing.pool.ThreadPool。以下示例将工作线程的数量限制为 2 个，因此可能需要长达 15 秒的时间才能完成（如果所有工作线程恰好都需要 5 秒）：

from multiprocessing.pool import ThreadPool
from time import sleep
from random import randint

def dosomething(var):
    sleep(randint(1,5))
    print(var)

array = ["a", "b", "c", "d", "e"]
with ThreadPool(processes=2) as pool:
    pool.map(dosomething, array)