selectorsモジュールのサンプルコード

pipe4.py

import os
import time
import fcntl
import selectors

read_fd, write_fd = os.pipe()
pid = os.fork()
if pid:
    # 親プロセス
    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
    fcntl.fcntl(read_fd, fcntl.F_SETFL, os.O_NONBLOCK)
    read_pipe = os.fdopen(read_fd, 'rb')
    content = b''
    sel = selectors.DefaultSelector()
    sel.register(read_fd, selectors.EVENT_READ)
    while True:
        events = sel.select()
        for selector_key, mask in events:
            if selector_key.fd != read_fd:
                continue
            data = read_pipe.read(5)
            if data:
                print(data)
                content += data
                if len(content) >= 5:
                    break
    read_pipe.close()