python大文件迭代器的流式读取，之前一直使用readlines()对于大文件可以迅速充满内存，之前用法太野蛮暴力，要使用xreadlines或是直接是f,

#!/usr/bin/env python
#encoding=utf-8
import codecs
count =0L
#for line in file("./search_click.data.20130501-20130814").readlines():
#for line in file("./search_click.data.20130501-20130814").xreadlines():
for line in codecs.open("./search_click.data.20130501-20130814"):
        count += 1
        print line