這篇文章主要介紹了Python3并發寫文件原理解析,文中通過示例代碼介紹的非常詳細，對大家的學習或者工作具有一定的參考學習價值,需要的朋友可以參考下

使用python2在進行并發寫的時候，發現文件會亂掉，就是某一行中間會插入其他行的內容。

但是在使用python3進行并發寫的時候，無論是多進程，還是多線程，都沒有出現這個問題，難道是python3的特性嗎？

import time

import os

import multiprocessing

from multiprocessing.dummy import Pool as ThreadPool

def write(val, file):

w = open(file, "a")

for i in range(100):

w.write("%s\n" % val)

time.sleep(0.001)

def thread_write(file):

res, pools = [], ThreadPool(10)

for i in range(10):

val = str(i) * 1000

res.append(pools.apply_async(func=write, args=(val, file, )))

while res:

for ret in res:

if ret.ready():

res.remove(ret)

time.sleep(0.01)

def mutil_write(file):

pools = multiprocessing.Pool(processes=10)

res = []

for i in range(100):

res.append(pools.apply_async(thread_write, args=(file, )))

while res:

for ret in res:

if ret.ready():

res.remove(ret)

time.sleep(0.01)

if __name__ == '__main__':

file = "./write_test"

mutil_write(file)

with open(file) as fb:

lines = 0

line_len = []

for line in fb:

lines += 1

line = line.strip()

line_len.append(len(line))

if len(line) != 1000:

raise(Exception("error line: %s, len: %d" % (line, len(line))))

print("lines:%d, max len:%d, min:%d, avg:%.2f" % (lines, max(line_len), min(line_len), sum(line_len)/len(line_len)))

os.remove(file)

上面代碼，多進程并發寫結束后，校驗每一行的長度是否是設置好的長度。用python3反復運行，均通過測試沒有異常。

$ python3 --version

Python 3.7.4

$ python3 t.py

lines:10000, max len:1000, min:1000, avg:1000.00

如果用python2，則會出現異常：

$ python2 --version

Python 2.7.15

$ python2 t.py

Traceback (most recent call last):

File "t.py", line 49, in

raise(Exception("error line: %s, len: %d" % (line, len(line))))

Exception: error line: 333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333330000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000, len: 1092

以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支持python博客。

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