python:multiprocessing.Pipe和重定向标准输出 [英] python: multiprocessing.Pipe and redirecting stdout
问题描述
我正在使用multiprocessing
包产生第二个进程,我想从中将stdout和stderr重定向到第一个进程.我正在使用multiprocessing.Pipe
对象:
I am using multiprocessing
package to spawn a second process from which I would like to redirect stdout and stderr into the first process. I am using multiprocessing.Pipe
object:
dup2(output_pipe.fileno(), 1)
其中output_pipe
是multiprocessing.Pipe
的实例.但是,当我尝试另一端阅读时,它只是挂起了.我尝试使用Pipe.recv_bytes
进行读取,但有限制,但会引发OSError
.完全有可能吗?还是我应该切换到一些较低级别的管道功能?
Where output_pipe
is an instance of multiprocessing.Pipe
. However, when I try to read on the other end, it just hangs. I tried reading using Pipe.recv_bytes
with a limit, but that raises an OSError
. Is this possible at all or should I just switch to some lower level pipe functions?
推荐答案
在Python 2.7中进行实验后,我得到了这个工作示例.使用os.dup2
管道的文件描述符被复制到标准输出文件描述符,并且每个print
函数最终都写入管道.
After experimenting in Python 2.7 I got this working example. With os.dup2
pipe's file descriptor is copied to standard output file descriptor, and each print
function ends up writing to a pipe.
import os
import multiprocessing
def tester_method(w):
os.dup2(w.fileno(), 1)
for i in range(3):
print 'This is a message!'
if __name__ == '__main__':
r, w = multiprocessing.Pipe()
reader = os.fdopen(r.fileno(), 'r')
process = multiprocessing.Process(None, tester_method, 'TESTER', (w,))
process.start()
for i in range(3):
print 'From pipe: %s' % reader.readline()
reader.close()
process.join()
输出:
From pipe: This is a message!
From pipe: This is a message!
From pipe: This is a message!
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