day10-多进程queue,manager，pipe

多线程： 不适合cpu密集操作型的任务，适合io操作密集型的任务

Queue  \ Pipe 只是实现进程间数据的传递
Manager 实现了进程间数据的共享，即多个进程可以修改同一份数据
1.进程间Queue传递数据

from multiprocessing import Process, Queue#声明为进程queue
def f(qq):
    print("in child:",qq.qsize())
    qq.put([42, None, 'hello'])#子进程修该队列
if __name__ == '__main__':
    q = Queue()#留意
    q.put("test123")#父进程修改队列
    p = Process(target=f, args=(q,))#在子线程初始化的时候就传入q队列
    p.start()
    p.join()
    print("444",q.get())
    print("444", q.get())

输出：

called from child process function f
module name: __mp_main__
parent process: 7904
process id: 6868

2.进程间Pipe传递数据

from multiprocessing import Process, Pipe
def f(conn):
    conn.send([42, None, 'hello from child'])
    conn.send([42, None, 'hello from child2'])
    print("from parent:",conn.recv())
    conn.close()

if __name__ == '__main__':
    parent_conn, child_conn = Pipe()#管道的两头（父子），一边一个
    p = Process(target=f, args=(child_conn,))
    p.start()
    print(parent_conn.recv())#子发父收  
    print(parent_conn.recv())  
    parent_conn.send("张洋可好")#父发子收
    p.join()
    # [42, None, 'hello from child']
    # [42, None, 'hello from child2']
    # from parent: 张洋可好

Managers进程同时修改相同数据：

from multiprocessing import Process, Manager
import os
def f(d, l):
    d[os.getpid()] =os.getpid()#进程ID
    l.append(os.getpid())
    print(l)
if __name__ == '__main__':
    with Manager() as manager:
        d = manager.dict() #{} #生成一个字典，可在多个进程间共享和传递
        l = manager.list(range(5))#生成一个列表，可在多个进程间共享和传递
        p_list = []
        for i in range(5):
            p = Process(target=f, args=(d, l))
            p.start()
            p_list.append(p)
        for res in p_list: #等待结果
            res.join()
        print(d)
        print(l)

# [0, 1, 2, 3, 4, 3576]
# [0, 1, 2, 3, 4, 3576, 9624]
# [0, 1, 2, 3, 4, 3576, 9624, 10212]
# [0, 1, 2, 3, 4, 3576, 9624, 10212, 9392]
# [0, 1, 2, 3, 4, 3576, 9624, 10212, 9392, 7904]
# {3576: 3576, 9624: 9624, 10212: 10212, 9392: 9392, 7904: 7904}
# [0, 1, 2, 3, 4, 3576, 9624, 10212, 9392, 7904]