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Is python compressed files efficient?

anonymity
anonymityOriginal
2019-06-17 11:33:203029browse

python压缩文件的效率高吗?这里使用shell脚本和Python脚本同样压缩文件进行对比,通过时间和压缩比对比发现Python的压缩比可以,但是效率低耗时较多。

Is python compressed files efficient?

Shell使用系统tar

Python使用tarfile模块,Python不开多线程的情况两者做文件打包压缩对比。

Python代码:

#-*- coding: utf-8 -*- 
#!/usr/bin/evn python 
""" 
USAGE: 
        Bak_rsync_Python.py version 
""" 
import sys 
import time 
import os 
import shutil 
import subprocess 
import tarfile 
 
rundir=os.getcwd() 
src_dir='/data/rsync_center' 
bak_dir='/data/backup/game/test' 
today=time.strftime("%Y_%m_%d", time.localtime()) 
 
def main(version): 
        #set local var 
        md5="/sbin/md5" 
        bak_file="rsync_center_"+today+"_"+version+".tgz" #多个变量联合做变量 
        md5_file=rundir+"/md5/"+bak_file+".md5" 
        cmd="%s %s > %s" % (md5,bak_file,md5_file)     
        #print bak_file 
        #print md5_file 
 
        #tar src dir 
        os.chdir(src_dir) 
        tar=tarfile.open(bak_file,'w|gz') 
        tar.add(src_dir) 
        tar.close() 
 
        #tgz file md5 
        ret=subprocess.call(cmd,shell=True) #subprocess.call返回值是退出状态 
        if ret !=0:              
                print "md5 failed" 
                sys.exit(1) 
        #else: print ret 
 
        #move tgz to dst dir 
        shutil.move(bak_file,bak_dir) 
 
 
if __name__=='__main__': 
        try: 
                len(sys.argv)!=2 
        except: 
                print "Please give version" 
                print __doc__ 
        else: 
                print "start at",time.ctime() 
                version=sys.argv[1] 
                main(version) 
                print "end at",time.ctime()

shell脚本:

#!/bin/sh - 
# Bak_rsync_Shell.sh version 
 
shell_dir=`pwd` 
src_dir=/data/rsync_center 
bak_dir="/data/backup/game/test" 
log_file=${shell_dir}/rsync_center_bak.log 
Version=$1 
Today=`/bin/date +%Y_%m_%d` 
Fourteenday=`/bin/date -v -8d +%Y_%m_%d` 
bak_file="rsync_center_${Today}_${Version}.tgz" 
md5_file=${shell_dir}/md5/$bak_file.md5 
 
if [ $# -ne 1 ] 
        then    echo "Please give a version!" 
                break 
else 
        startdate=`date "+%Y-%m-%d %H:%M:%S"` 
        echo "rsync_center backup Start  at " $startdate 
        cd $src_dir 
        tar -zcf $bak_file ./ 
        /sbin/md5 $bak_file > $md5_file 
        mv $bak_file $bak_dir/ 
        enddate=`date "+%Y-%m-%d %H:%M:%S"` 
        echo "rsync_center backup Complete at" $enddate 
fi

运行对比:

#du -sh /data/rsync_center/
112M    /data/rsync_center/
#sh Bak_rsync_Shell.sh testShell
rsync_center backup Start  at  2012-03-15 14:53:37
tar: ./rsync_center_2012_03_15_testShell.tgz: Can't add archive to itself
rsync_center backup Complete at 2012-03-15 14:53:46

使用了9秒

#python Bak_rsync_Python.py testPython
start at Thu Mar 15 14:54:54 2012
end at Thu Mar 15 14:55:20 2012

使用了27秒

压缩大小差不多

#ll -h /data/backup/game/test/ | awk '{print$5,$9}'
49M rsync_center_2012_03_15_testPython.tgz
49M rsync_center_2012_03_15_testShell.tgz

python使用代码53行(取出注释也有40行),shell使用代码26行

python的逻辑更复杂,shell更简单一点。

 

可见python在单线程的情况下,对于系统基本文件处理,比如复制移动,打包压缩不如shell简单高效。逻辑上也不利于SA快速理解。所以,Python在基本的系统管理上,可能不如Shell.

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