python基础-线程和进程

# multiprocessing.py
import os

print ‘Process (%s) start...‘ % os.getpid()
pid = os.fork()　　　　　　#windows系统下没有fork()调用,so,只能在posix的系统下执行(Unix,Linux,Mac,BSD...)
if pid==0:
    print ‘I am child process (%s) and my parent is %s.‘ % (os.getpid(), os.getppid())
else:
    print ‘I (%s) just created a child process (%s).‘ % (os.getpid(), pid)

Process (876) start...
I (876) just created a child process (877).
I am child process (877) and my parent is 876.

from multiprocessing import Process
import os

# 子进程要执行的代码
def run_proc(name):
    print ‘Run child process %s (%s)...‘ % (name, os.getpid())

if __name__==‘__main__‘:
    print ‘Parent process %s.‘ % os.getpid()
    p = Process(target=run_proc, args=(‘test‘,))
    print ‘Process will start.‘
    p.start()　　　　#启动进程
    p.join()　　　　 #等待子进程结束后再继续往下运行，通常用于进程间的同步。
    print ‘Process end.‘

from multiprocessing import Pool
import os, time, random

def long_time_task(name):
    print ‘Run task %s (%s)...‘ % (name,os.getpid())
    start = time.time()
    time.sleep(random.random() * 3)　　#随机暂停
    end = time.time()
    print ‘Task %s runs %0.2f seconds.‘ % (name,(end-start))

if __name__==‘__main__‘:
    print ‘Parent process %s.‘ % os.getpid()
    p = Pool()　　　　　　#创建一个进程池.
    for i in range(5):
        p.apply_async(long_time_task,args=(i,))　　#将要执行的函数加入进程池
    print ‘Waiting for all subprocesses done....‘
    p.close()
    p.join()    #等待所有子进程执行完毕,之前必须先调用close(),然后不能添加新的Process.
    print ‘All subprocessesdone.‘

Parent process 1356.
Waiting for all subprocesses done....
Run task 3 (6296)...
Task 3 runs 0.52 seconds.
Run task 2 (4244)...
Task 2 runs 1.58 seconds.
Run task 0 (5720)...
Task 0 runs 1.48 seconds.
Run task 1 (7692)...
Task 1 runs 2.55 seconds.
Run task 4 (1860)...
Task 4 runs 2.96 seconds.
All subprocessesdone.
[Finished in 3.3s]

p = Pool(5)

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

#写数据进程执行的代码：
def write(q):
    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):
    while True:
        if q.empty():
            return
        else:
            value = q.get()
            print value,‘from Queue‘

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,pr结束：    
    pw.join()
    pr.terminate()