forkとpipeモジュールのサンプル(fd閉じるようにしたやつ)

pipe6.py

import os
import time
import fcntl
import select

read_fd, write_fd = os.pipe()
pid = os.fork()
if pid:
    # 親プロセス
    # 読み込み側のfdは使わないのでclose
    os.close(read_fd)
    write_pipe = os.fdopen(write_fd, 'wb')
    for b in b'hello':
        time.sleep(2)
        write_pipe.write(bytes([b]))
        write_pipe.flush()
    write_pipe.close()
else:
    # 子プロセス
    # 書き込み側のfdは使わないのでclose
    os.close(write_fd)
    fcntl.fcntl(read_fd, fcntl.F_SETFL, os.O_NONBLOCK)
    read_pipe = os.fdopen(read_fd, 'rb')
    content = b''
    poller = select.poll()
    poller.register(read_fd, select.POLLIN)
    while True:
        events = poller.poll()
        for fd, event in events:
            if fd != read_fd:
                continue
            data = read_pipe.read()
            if data:
                print(data)
                content += data
                if len(content) >= 5:
                    break
    read_pipe.close()