Python基础5

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(‘Child process will start.‘)
    p.start()
    p.join()  #join()方法可以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(‘Child process end.‘)

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()