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python 实时遍历日志文件

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Release： 2016-06-10 15:05:16
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open 遍历一个大日志文件

使用 readlines() 还是 readline() ?

总体上 readlines() 不慢于python 一次次调用 readline()，因为前者的循环在C语言层面，而使用readline() 的循环是在Python语言层面。

但是 readlines() 会一次性把全部数据读到内存中，内存占用率会过高，readline() 每次只读一行，对于读取 大文件， 需要做出取舍。

如果不需要使用 seek() 定位偏移， for line in open('file') 速度更佳。

使用 readlines()，适合量级较小的日志文件

import os
import time
def check():
p = 
while True:
f = open("log.txt", "r+")
f = open("result.txt", "a+")
f.seek(p, )
#readlines()方法
filelist = f.readlines()
if filelist:
for line in filelist:
#对行内容进行操作
f.write(line)
#获取当前位置，为下次while循环做偏移
p = f.tell()
print 'now p ', p
f.close()
f.close()
time.sleep()
if __name__ == '__main__':
check()
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使用 readline()，避免内存占用率过大

import os
import time
def check():
p = 
while True:
f = open("log.txt", "r+")
f = open("result.txt", "a+")
f.seek(p, )
#while readline()方法
while True:
l = f.readline()
#空行同样为真
if l:
#对行内容操作
f.write(l)
else:
#获取当前位置，作为偏移值
p = f.tell()
f.close()
f.close()
break
print 'now p', p
time.sleep()
if __name__ == '__main__':
check()
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Related labels：
python遍历日志文件 python日志文件
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