我刚开始学习 Python 的管道方法。 我试着把管道描述符封装成文件对象,然后逐行读取。
import os,time,threading
def child():
while True:
time.sleep(1)
msg = ('Spam\n' ).encode()
os.write(pipeout,msg)
def parent():
while True:
a = os.fdopen(pipein)
line = a.readline()[:-1]
print('Parent %d got [%s] at %s' % (os.getpid(),line,time.time()))
pipein,pipeout = os.pipe()
threading.Thread(target=child,args=()).start()
parent()
当我运行这段脚本时,结果如下——它只在第一次迭代中工作,然后显示错误消息。
Parent 621 got [Spam] at 1376785841.4
Traceback (most recent call last):
File "/Users/miteji/pipe-thread.py", line 43, in <module>
parent()
File "/Users/miteji/pipe-thread.py", line 36, in parent
line = a.readline()[:-1]
IOError: [Errno 9] Bad file descriptor
>>> Exception in thread Thread-1:
Traceback (most recent call last):
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/threading.py", line 551, in __bootstrap_inner
self.run()
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/threading.py", line 504, in run
self.__target(*self.__args, **self.__kwargs)
File "/Users/miteji/pipe-thread.py", line 30, in child
os.write(pipeout,msg)
OSError: [Errno 32] Broken pipe
然而,当我进行了改变
a = os.fdopen(pipein)
line = a.readline()[:-1]
to
line = os.read(pipein,32)
这个脚本运行正常。
为什么不能使用"os.fdopen"方法?为什么管道断开了?谢谢大家!