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1 基础例子
1.1 输出顺序的不同
[root@localhost pydoc]# ./tmp.py
worker 0
worker 1
worker 2
worker 3
worker 4
[root@localhost pydoc]# ./tmp.py
worker 0
worker 1
worker 2
worker 4
worker 3
1.2 简单的代码实现
[root@localhost pydoc]# cat tmp.py
#!/usr/bin/env python
#coding=utf-8
from multiprocessing import Process
def worker(num):
"""test python multi process"""
print 'worker',num
return
def main():
jobs = []
for i in range(5):
p = Process(target=worker,args=(i,))
jobs.append(p)
p.start()
if __name__=='__main__':
main()
2 僵尸进程
要等待一个进程完成工作并退出，可以使用join()方法。在Linux上，当某个进程终结之后，需要被主进程调用wait，否则进程会成为僵尸进程。所以，有必要对每个Process对象调用join()方法，实际上等同于wait。
[root@localhost pydoc]# cat tmp.py
#!/usr/bin/env python
#coding=utf-8
from multiprocessing import Process
def worker(num):
"""test python multi process"""
print 'worker',num
return
def main():
jobs = []
for i in range(5):
p = Process(target=worker,args=(i,))
jobs.append(p)
p.start()
##to avoid defunct process,you should call join()
for j in jobs:
j.join()
if __name__=='__main__':
main()
3 开源项目MTOP
MySQL MTOP是一个由Python+PHP开发的开源MySQL企业级监控系统，系统由Python实现多进程数据采集和监控，PHP实现web展示和管理。
有兴趣的同学可以参考它的官方网站 www.mtop.cc，这里主要介绍它是如何用Python来开发多进程数据采集和监控。
3.1 启动MTOP
[root@localhost mysqlmtop]# mtopctl status
mysql mtop is not run!
[root@localhost mysqlmtop]# mtopctl start
nohup: 把输出追加到"nohup.out"
mysql mtop start success!
[root@localhost mysqlmtop]# mtopctl status
mysql mtop is run!
[root@localhost mysqlmtop]# ps -ef | grep mtop
root 4463 4446 0 11:21 pts/2 00:00:00 vim mtopd.py
root 7119 1 0 14:50 pts/3 00:00:00 /bin/bash /usr/local/bin/mtopctl start
root 7121 7119 1 14:50 pts/3 00:00:00 python ./mtopd.py
root 7125 7121 0 14:50 pts/3 00:00:00 python ./mtopd.py
root 7126 7121 0 14:50 pts/3 00:00:00 python ./mtopd.py
root 7129 7121 0 14:50 pts/3 00:00:00 python ./mtopd.py
root 7130 7121 0 14:50 pts/3 00:00:00 python ./mtopd.py
root 7133 7121 0 14:50 pts/3 00:00:00 python ./mtopd.py
root 7134 7121 0 14:50 pts/3 00:00:00 python ./mtopd.py
root 7186 6613 0 14:50 pts/3 00:00:00 grep mtop
从ps的输出我们也能清楚知道，pid为7121的父进程产生了6个子进程
3.2 MTOP多进程数据采集的主干代码
代码比较简单，看下基础例子基本也就明了。
[root@localhost mysqlmtop]# cat mtopd.py
#!/bin/env python
#coding:utf-8
import os, sys, string, time, datetime, traceback;
from multiprocessing import Process;
import global_functions as func
def job_run(script_name,times):
while True:
os.system("./"+script_name)
time.sleep(int(times))
def main():
print("%s: controller started." % (time.strftime('%Y-%m-%d %H:%M:%S', time.localtime()),))
monitor = func.get_option('monitor')
monitor_status = func.get_option('monitor_status')
monitor_replication = func.get_option('monitor_replication')
monitor_process = func.get_option('monitor_process')
alarm = func.get_option('alarm')
frequency_monitor = func.get_option('frequency_monitor')
frequency_alarm = func.get_option('frequency_alarm')
kill_process = func.get_option('kill_process')
joblist = []
if monitor=="1":
if monitor_status=="1":
job = Process(target = job_run, args = ('check_mysql_status_ext.py',frequency_monitor))
joblist.append(job)
job.start()
job = Process(target = job_run, args = ('check_mysql_status.py',frequency_monitor))
joblist.append(job)
job.start()
if monitor_replication=="1":
job = Process(target = job_run, args = ('check_mysql_replication.py',frequency_monitor))
joblist.append(job)
job.start()
if monitor_process=="1":
job = Process(target = job_run, args = ('check_mysql_process.py',4))
joblist.append(job)
job.start()
if alarm=="1":
job = Process(target = job_run, args = ('alarm_mysql.py',frequency_alarm))
joblist.append(job)
job.start()
if kill_process=="1":
job = Process(target = job_run, args = ('admin_mysql_kill_process.py',3))
joblist.append(job)
job.start()
for job in joblist:
job.join();
print("%s: controller finished." % (time.strftime('%Y-%m-%d %H:%M:%S', time.localtime()),))
if __name__ == '__main__':
main()
Good Luck！