python - 如何在python中将文件描述符从父级传递给子级？

Question

我正在使用多处理模块，并使用池来启动多个工作程序。但是在父进程中打开的文件描述符在工作进程中关闭。我希望他们开放..!有什么方法可以传递文件描述符以在父子之间共享？

Answer 1

在 Python 2 和 Python 3 上，发送和接收文件描述符的函数存在于 multiprocessing.reduction 模块中。

示例代码(Python 2 和 Python 3):

import multiprocessing
import os

# Before fork
child_pipe, parent_pipe = multiprocessing.Pipe(duplex=True)

child_pid = os.fork()

if child_pid:
    # Inside parent process
    import multiprocessing.reduction
    import socket
    # has socket_to_pass socket object which want to pass to the child
    socket_to_pass = socket.socket(socket.AF_UNIX, socket.SOCK_DGRAM)
    socket_to_pass.connect("/dev/log")
    # child_pid argument to send_handle() can be arbitrary on Unix,
    # on Windows it has to be child PID
    multiprocessing.reduction.send_handle(parent_pipe, socket_to_pass.fileno(), child_pid)
    socket_to_pass.send("hello from the parent process\n".encode())
else:
    # Inside child process
    import multiprocessing.reduction
    import socket
    import os
    fd = multiprocessing.reduction.recv_handle(child_pipe)
    # rebuild the socket object from fd
    received_socket = socket.fromfd(fd, socket.AF_INET, socket.SOCK_STREAM)
    # socket.fromfd() duplicates fd, so we can close the received one
    os.close(fd)
    # and now you can communicate using the received socket
    received_socket.send("hello from the child process\n".encode())