from multiprocessing import Process

def run(num):

    print 'this is ',num

for i in range(10):

    t = Process(target=run,args=(i,))

    t.start()

from multiprocessing import Process

import os

def info(title):

        print title

        print 'module name:',__name__

        if hasattr(os,'getppid'):

                print 'parent process:',os.getppid()    #获取父进程PID

print 'process id:',os.getpid()                 #获取子进程PID

def f(name):

        info('function f')  #子进程调用info函数

print 'hello',name

if __name__ == '__main__':

        info('main line')   #父进程调用info函数

print '---------------'

p = Process(target=f,args=('bob',))

        p.start()

        p.join()

from multiprocessing import Process

li = []

def run(num):

    li.append(num)

    print 'say hi',li

for i in range(10):

    t = Process(target=run,args=(i,))

    t.start()

print 'ending',li

from multiprocessing import Process,Array

#创建一个只包含数字类型的一个数组/列表，并且个数不可变

temp = Array('i', [11,22,33,44])

def Foo(i):

    temp[i] = 100+i

    for item in temp:

        print i,'----->',item

for i in range(2):

    p = Process(target=Foo,args=(i,))

    p.start()

from multiprocessing import Process,Manager

manage = Manager()

dic = manage.dict()

def Foo(i):

    dic[i] = 100+i

    print dic.values()

for i in range(2):

    p = Process(target=Foo,args=(i,))

    p.start()

    p.join()

from multiprocessing import Process,Queue

def f(q,n):

    q.put([n,'hello'])

if __name__ == '__main__':

    q = Queue()

    for i in range(5):

        p = Process(target=f,args=(q,i))

        p.start()

    while True:

        print q.get()

from multiprocessing import Process,Manager

def f(d,l):

    d[1] = '1'

d['2'] = 2

d[0.25] = None

l.reverse()     #反向列表

if __name__ == '__main__':

    manager = Manager()

    d = manager.dict()

    #d = {}

l = manager.list(range(10))

    #l = [0,1,2,4,5,6,7,8,9]

p = Process(target=f,args=(d,l))

    p.start()

    p.join()

    print d

    print l

from multiprocessing import Process, Array, RLock

def Foo(lock,temp,i):

    """

将第0个数加100

    """

lock.acquire()      #加锁

temp[0] = 100+i

    for item in temp:

        print i,'----->',item

    lock.release()      #解锁

lock = RLock()

temp = Array('i', [11, 22, 33, 44])

for i in range(20):

    p = Process(target=Foo,args=(lock,temp,i,))

    p.start()

from  multiprocessing import Process,Pool

import time

def Foo(i):

    time.sleep(2)

    return i+100

def Bar(arg):

    print arg

pool = Pool(5)

#print pool.apply(Foo,(1,))

#print pool.apply_async(func =Foo, args=(1,)).get()

for i in range(10):

    pool.apply_async(func=Foo, args=(i,),callback=Bar)

print 'end'

pool.close()

pool.join()#进程池中进程执行完毕后再关闭，如果注释，那么程序直接关闭。

from multiprocessing import Pool

import time

def f(x):

    print x*x

    #time.sleep(2)

return x*x

if __name__ == '__main__':

    pool = Pool(processes=2)   #同时5个进程

res_list = []

    for i in range(5):

        res = pool.apply_async(f,[i,])

        #res =  Process(target=f,args=[i,])

print '-----------',i

        res_list.append(res)

    for r in res_list:

        print 'res_list:',r.get()

协程

线程和进程的操作是由程序触发系统接口，最后的执行者是系统；协程的操作则是程序员。

协程存在的意义：对于多线程应用，CPU通过切片的方式来切换线程间的执行，线程切换时需要耗时（保存状态，下次继续）。协程，则只使用一个线程，在一个线程中规定某个代码块执行顺序。

协程的适用场景：当程序中存在大量不需要CPU的操作时（IO），适用于协程；

greenlet

#!/usr/bin/env python

# -*- coding:utf-8 -*-

from greenlet import greenlet

def test1():

    print 12

    gr2.switch()

    print 34

    gr2.switch()

def test2():

    print 56

    gr1.switch()

    print 78

gr1 = greenlet(test1)

gr2 = greenlet(test2)

gr1.switch()

gevent

import gevent

def foo():

    print('Running in foo')

    gevent.sleep(0)

    print('Explicit context switch to foo again')

def bar():

    print('Explicit context to bar')

    gevent.sleep(0)

    print('Implicit context switch back to bar')

gevent.joinall([

    gevent.spawn(foo),

    gevent.spawn(bar),

])

遇到IO操作自动切换：

from gevent import monkey; monkey.patch_all()

import gevent

import urllib2

def f(url):

    print('GET: %s' % url)

    resp = urllib2.urlopen(url)

    data = resp.read()

    print('%d bytes received from %s.' % (len(data), url))

gevent.joinall([

        gevent.spawn(f, 'https://www.python.org/'),

        gevent.spawn(f, 'https://www.yahoo.com/'),

        gevent.spawn(f, 'https://github.com/'),

])