Python: How to read stdout of subprocess in a nonblocking way(Python:如何以非阻塞方式读取子进程的标准输出)
问题描述
我正在尝试制作一个简单的 python 脚本来启动一个子进程并监视其标准输出.以下是代码片段:
I am trying to make a simple python script that starts a subprocess and monitors its standard output. Here is a snippet from the code:
process = subprocess.Popen([path_to_exe, os.path.join(temp_dir,temp_file)], stdout=subprocess.PIPE)
while True:
output=process.stdout.readline()
print "test"
问题在于脚本在 output=process.stdout.readline()
上挂起,并且 print "test"
行仅在子进程终止后执行.
The problem is that the script hangs on output=process.stdout.readline()
and that the line print "test"
only executes after the subprocess is terminated.
有没有办法读取标准输出并打印它而不必等待子进程终止?
Is there a way to read standard output and print it without having to wait for the subprocess to terminate?
我要启动的子进程是一个 Windows 二进制文件,我没有它的源代码.
The subprocess which I am starting is a Windows binary for which I do not have the source code.
我发现了几个类似的问题,但答案仅适用于 Linux 或如果我有我要启动的 suprocess 的来源.
I have found several similar questions, but the answers are only applicable on Linux or in case I have the source of the suprocess I am starting.
推荐答案
勾选select 模块
import subprocess
import select
import time
x=subprocess.Popen(['/bin/bash','-c',"while true; do sleep 5; echo yes; done"],stdout=subprocess.PIPE)
y=select.poll()
y.register(x.stdout,select.POLLIN)
while True:
if y.poll(1):
print x.stdout.readline()
else:
print "nothing here"
time.sleep(1)
非 posix 系统的线程解决方案:
Threaded Solution for non posix systems:
import subprocess
from threading import Thread
import time
linebuffer=[]
x=subprocess.Popen(['/bin/bash','-c',"while true; do sleep 5; echo yes; done"],stdout=subprocess.PIPE)
def reader(f,buffer):
while True:
line=f.readline()
if line:
buffer.append(line)
else:
break
t=Thread(target=reader,args=(x.stdout,linebuffer))
t.daemon=True
t.start()
while True:
if linebuffer:
print linebuffer.pop(0)
else:
print "nothing here"
time.sleep(1)
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本文标题为:Python:如何以非阻塞方式读取子进程的标准输出


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