Python3并发写文件与Python对比_python多线程写文件资源-CSDN文库

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Python3并发写文件与并发写文件与Python对比对比

这篇文章主要介绍了Python3并发写文件原理解析,文中通过示例代码介绍的非常详细，对大家的学习或者工作具有一定的参考学习价值,需要的朋友可以参考下

使用python2在进行并发写的时候，发现文件会乱掉，就是某一行中间会插入其他行的内容。

但是在使用python3进行并发写的时候，无论是多进程，还是多线程，都没有出现这个问题，难道是python3的特性吗？

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" % 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)

上面代码，多进程并发写结束后，校验每一行的长度是否是设置好的长度。用python3反复运行，均通过测试没有异常。

$ python3 --version

Python 3.7.4

$ python3 t.py

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

如果用python2，则会出现异常：

$ python2 --version

Python 2.7.15

$ python2 t.py

Traceback (most recent call last):

File "t.py", line 49, in <module>

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

Exception: error line:

333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333330000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000,

len: 1092