python 进程和线程-简介及进程

import os
from multiprocessing import Process


#子进程要执行的代码
def run_process(name):
	print('子进程Id是%s,传过来的参数是%s'%(os.getpid(),name))
if __name__ == "__main__":
	r=Process(target=run_process,args=('参数1',))
	r.start()
	r.join()
#输出
子进程Id是17020,传过来的参数是参数1

import os,random,time
from multiprocessing import Pool

def run_process(name):
	print('子进程Id:%s开始执行,传过来的参数是%s'%(os.getpid(),name))
	time.sleep(random.random())#这是为了增加进程的执行时间，以便观测到同时执行进程的最大个数
	print('子进程Id:%s执行结束'%(os.getpid()))
if __name__ == "__main__":
	p=Pool(4)#通过4来指定进程池中能同时执行的进程数
	for i in range(5):
		p.apply_async(run_process,args=(i,))#这样向进程池中添加进程来创建
	p.close()#使用close（）来关闭向进程池中添加进程
	p.join()

#输出
子进程Id:22808开始执行,传过来的参数是0
子进程Id:2992开始执行,传过来的参数是1
子进程Id:16776开始执行,传过来的参数是2
子进程Id:16304开始执行,传过来的参数是3
子进程Id:2992执行结束
子进程Id:2992开始执行,传过来的参数是4
子进程Id:22808执行结束
子进程Id:2992执行结束
子进程Id:16304执行结束
子进程Id:16776执行结束

import subprocess

print('$ nslookup www.python.org')
r = subprocess.call(['nslookup', 'www.python.org'])
print('Exit code:', r)#r可以看作是上是’nslookup www.python.org‘命令执行后的返回状态码


#输出
$nslookup www.python.org
服务器:  UnKnown
Address:  10.0.100.101

非权威应答:
名称:    dualstack.python.map.fastly.net
Addresses:  2a04:4e42:6::223
          151.101.24.223
Aliases:  www.python.org

Exit code  0

import subprocess

print('$ nslookup')
p = subprocess.Popen(['nslookup'], stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
output, err = p.communicate(b'set q=mx\npython.org\nexit\n')
print(output.decode('gbk'))#windows默认使用的字符编码
print('Exit code:', p.returncode)

#输出
$ nslookup
Server:		192.168.19.4
Address:	192.168.19.4#53

Non-authoritative answer:
python.org	mail exchanger = 50 mail.python.org.

Authoritative answers can be found from:
mail.python.org	internet address = 82.94.164.166
mail.python.org	has AAAA address 2001:888:2000:d::a6


Exit code: 0

set q=mx
python.org
exit

from multiprocessing import Process, Queue
import os, time, random

# 写数据进程执行的代码:
def write(q):
    print('Process to write: %s' % os.getpid())
    for value in ['A', 'B', 'C']:
        print('Put %s to queue...' % value)
        q.put(value)
        time.sleep(random.random())

# 读数据进程执行的代码:
def read(q):
    print('Process to read: %s' % os.getpid())
    while True:
        value = q.get(True)
        print('Get %s from queue.' % value)

if __name__=='__main__':
    # 父进程创建Queue，并传给各个子进程：
    q = Queue()
    pw = Process(target=write, args=(q,))
    pr = Process(target=read, args=(q,))
    # 启动子进程pw，写入:
    pw.start()
    # 启动子进程pr，读取:
    pr.start()
    # 等待pw结束:
    pw.join()
    # pr进程里是死循环，无法等待其结束，只能强行终止:
    pr.terminate()

#输出
Process to write: 50563
Put A to queue...
Process to read: 50564
Get A from queue.#会一次从queue中读取所有的，比如将wirte中改为，put两次
Put B to queue...
Get B from queue.
Put C to queue...
Get C from queue.