Python 多CPU编程
因为工作需要，从Python 2.5开始学习Python，当然只是简单的使用Python完成一些工作，没有很少深入学习。一次，在一个多CPU的环境中，想用Python的多线程编程来达到使用完系统的CPU的目的，结果是不行的。最后发现，Python 2.6以后提供了一个multiprocessing的库，可以达到这个目的。
分享如下：
##多线程编程
[root@AS-1 bin]# cat z.py
# -*- coding:utf-8 -*-
import os
import threading
def test():
while True:
65535+65535
if __name__ == “__main__”:
for n in range(20):
print ‘Proc(%d) Start…’%n
p = threading.Thread(target=test, args=())
p.start()
##运行情况。见红色字体，只占用了一个CPU，系统CPU Idle 99.5%
[root@AS-1 bin]# ./python z.py &
Proc(0) Start…
Proc(1) Start…
Proc(2) Start…
Proc(3) Start…
Proc(4) Start…
Proc(5) Start…
Proc(6) Start…
Proc(7) Start…
Proc(8) Start…
Proc(9) Start…
Proc(10) Start…
Proc(11) Start…
Proc(12) Start…
Proc(13) Start…
Proc(14) Start…
Proc(15) Start…
Proc(16) Start…
Proc(17) Start…
Proc(18) Start…
Proc(19) Start…
[root@AS-1 bin]# top -n 1
top – 03:06:56 up 30 days, 31 min, 3 users, load average: 1.25, 1.05, 0.65
Tasks: 320 total, 1 running, 300 sleeping, 19 stopped, 0 zombie
Cpu(s): 0.3%us, 0.1%sy, 0.0%ni, 99.5%id, 0.0%wa, 0.0%hi, 0.1%si, 0.0%st
Mem: 32953084k total, 7391604k used, 25561480k free, 276480k buffers
Swap: 34996216k total, 347648k used, 34648568k free, 3761504k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
25736 root 16 0 273m 4380 1664 S 127.6 0.0 0:34.65 python
25783 root 15 0 12864 1164 728 R 2.0 0.0 0:00.01 top
1 root 15 0 10344 564 528 S 0.0 0.0 0:02.16 init
## 多CPU编程， 见红色字体，用到了多个CPU（核/线程），系统CPU Idle为0.0%
[root@AS-1 bin]# cat x.py
# -*- coding:utf-8 -*-
import os
from multiprocessing import *
def test():
while True:
65535+65535
if __name__ == “__main__”:
for n in range(20):
print “Proc(%d) Start…”%n
p = Process(target = test, args = [])
p.start()
[root@AS-1 bin]# ./python x.py
Proc(0) Start…
Proc(1) Start…
Proc(2) Start…
Proc(3) Start…
Proc(4) Start…
Proc(5) Start…
Proc(6) Start…
Proc(7) Start…
Proc(8) Start…
Proc(9) Start…
Proc(10) Start…
Proc(11) Start…
Proc(12) Start…
Proc(13) Start…
Proc(14) Start…
Proc(15) Start…
Proc(16) Start…
Proc(17) Start…
Proc(18) Start…
Proc(19) Start…
[root@AS-1 bin]# top
top – 03:09:44 up 30 days, 33 min, 3 users, load average: 6.20, 2.14, 1.07
Tasks: 341 total, 22 running, 299 sleeping, 20 stopped, 0 zombie
Cpu(s):100.0%us, 0.0%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Mem: 32953084k total, 7407396k used, 25545688k free, 276568k buffers
Swap: 34996216k total, 347648k used, 34648568k free, 3762068k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
25940 root 25 0 83464 3364 468 R 100.0 0.0 0:21.25 python
25944 root 25 0 83464 3364 468 R 100.0 0.0 0:21.24 python
25945 root 25 0 83464 3364 468 R 100.0 0.0 0:21.18 python
25946 root 25 0 83464 3364 468 R 100.0 0.0 0:21.24 python
25948 root 25 0 83464 3368 468 R 100.0 0.0 0:21.15 python
25949 root 25 0 83464 3368 468 R 100.0 0.0 0:21.23 python
25951 root 25 0 83464 3372 468 R 100.0 0.0 0:21.21 python
25952 root 25 0 83464 3372 468 R 100.0 0.0 0:21.23 python
25953 root 25 0 83464 3380 468 R 100.0 0.0 0:21.22 python
25954 root 25 0 83464 3380 468 R 100.0 0.0 0:21.20 python
25943 root 25 0 83464 3364 468 R 99.6 0.0 0:21.21 python
25950 root 25 0 83464 3368 468 R 99.6 0.0 0:21.15 python
25959 root 25 0 83464 3388 468 R 50.5 0.0 0:10.53 python
25947 root 25 0 83464 3364 468 R 50.2 0.0 0:10.63 python
25957 root 25 0 83464 3384 468 R 50.2 0.0 0:10.53 python
25958 root 25 0 83464 3388 468 R 50.2 0.0 0:10.56 python
25941 root 25 0 83464 3364 468 R 49.8 0.0 0:10.72 python
25942 root 25 0 83464 3364 468 R 49.8 0.0 0:10.70 python
25955 root 25 0 83464 3384 468 R 49.8 0.0 0:10.62 python
25956 root 25 0 83464 3384 468 R 49.8 0.0 0:10.61 python
25976 root 15 0 12868 1276 816 R 0.3 0.0 0:00.03 top
1 root 15 0 10344 564 528 S 0.0 0.0 0:02.16 init