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Python编程：multiprocessing多进程（代码实例）

2018年02月07日  | 移动技术网IT编程  | 我要评论

八字成语大全,马玉剑,gai团队谈退赛歌手

获取进程id

import multiprocessing
import os

def foo():
    print(__name__)
    print("parent:", os.getppid())
    print("current:", os.getpid())

if __name__ == "__main__":
    foo()  # 主进程调用

    p = multiprocessing.Process(target=foo)
    p.start()  # 新开进程调用

    """
    __main__
    parent: 952
    current: 188
    __mp_main__
    parent: 188
    current: 6492
    """

多进程测试

import multiprocessing
import time, threading
from pycharm_fontcolor import Colors, FontColor

def func(i):
    print(FontColor.set_color("线程号:{}".format(threading.get_ident()), Colors.green), i)

def foo(i):
    print(FontColor.set_color("进程:", Colors.red), i)
    t = threading.Thread(target=func, args=(i,))  # 进程中新开线程
    t.start()

if __name__ == "__main__":
    start_time = time.time()

    for i in range(5):
        p = multiprocessing.Process(target=foo, args=(i,))
        p.start()

    end_time = time.time()

    print(FontColor.set_color("时间:", Colors.blue), end_time - start_time)

    """
    时间: 0.05303597450256348
    进程: 0
    线程号:8968 0
    进程: 1
    线程号:7620 1
    进程: 2
    进程: 3
    线程号:9204 2
    线程号:2492 3
    进程: 4
    线程号:6512 4
    """

进程池

from multiprocessing import  Pool
import time, os

def foo(i):
    time.sleep(2)
    print("process:", i, os.getpid())
    return i + 1  # 参数将传递给回调函数

def bar(i): # 做回调函数，由主进程执行
    print("bar", i, os.getpid())


if __name__ == "__main__":
    print(os.getpid())
    pool = Pool(processes=3)  # 允许同时放入3个进程
    for i in range(10):
        # p = pool.apply(func=foo, args=(i,))  # 串行
        p = pool.apply_async(func=foo, args=(i,), callback=bar)  # 并行

    print("done")
    pool.close()  # 先关闭入口
    pool.join()  # 在等待执行
    """
    8120
    done
    process: 0 5452
    bar 1 8120
    process: 1 8360
    bar 2 8120
    process: 2 7908
    bar 3 8120
    process: 3 5452
    bar 4 8120
    process: 4 8360
    bar 5 8120
    process: 5 7908
    bar 6 8120
    process: 6 5452
    bar 7 8120
    process: 7 8360
    bar 8 8120
    process: 8 7908
    bar 9 8120
    process: 9 5452
    bar 10 8120
    """

进程队列

from multiprocessing import Process, Queue

def foo(q):
    q.put("你好")

if __name__ == "__main__":
    q = Queue()  # 进程队列
    p = Process(target=foo, args=(q,))
    # p = Thread(target=foo, args=(q,))
    p.start()

    print(q.get())  # 你好

进程管道

from multiprocessing import Process, Pipe

def foo(conn):
    conn.send("hello")
    conn.close()

if __name__ == "__main__":
    parent_conn, child_conn = Pipe()  # 管道传送数据

    p = Process(target=foo, args=(child_conn,))
    p.start()

    print(parent_conn.recv())  # hello

多进程实现数据共享

from multiprocessing import Process, Manager
import os

def foo(dct, lst):
    dct[os.getpid()] = os.getpid()
    lst.append(os.getpid())
    print(os.getpid())

if __name__ == "__main__":
    manager = Manager()  # 实现进程间共享数据
    dct = manager.dict()
    lst = manager.list()
    processes = []
    for i in range(5):
        p = Process(target=foo, args=(dct, lst))
        p.start()
        processes.append(p)

    for process in processes:  # 等待结果
        process.join()

    print(dct)
    print(lst)

    """
    3816 5376 7500 8332 1124
    {3816: 3816, 5376: 5376, 8332: 8332, 7500: 7500, 1124: 1124}
    [3816, 5376, 7500, 8332, 1124]
    """

进程锁

from multiprocessing import Lock, Process

def foo(lock, i):
    lock.acquire()
    print("hello world!", i)
    lock.release()

if __name__ == "__main__":  # 主动执行会继续下面的内容，被当做模块调用则不会
    lock = Lock()  # 实例化进程锁
    for i in range(5):
        p = Process(target=foo, args=(lock, i))
        p.start()

    """
    hello world! 2
    hello world! 1
    hello world! 0
    hello world! 3
    hello world! 4
    """

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