[英]Getting the output unbuffered from subprocess is not working Python
I have an exectuable that if i run it with flags it starts a tool that generate messages all the time. 我有一个可执行程序,如果我用标志运行它,它将启动一个始终生成消息的工具。 When i try to run it with subprocess i get the output to the cmd and that is fine.
当我尝试使用子进程运行它时,我将输出输出到cmd,这很好。 The thing is that i want to take this messages and do something with them but for some reason the unbuffring method is not working and I'm not getting any message .
问题是我想接收这些消息并对它们执行某些操作,但是由于某种原因,取消缓冲的方法不起作用,并且我也没有收到任何消息。
The following is the code that I tried : 以下是我尝试过的代码:
p = subprocess.Popen(
["my_tool.exe","runMode","y","port","1234"],stdout=subprocess.PIPE,stderr=subprocess.STDOUT, bufsize=1)
To generate the output tried the folloing: 要生成输出,请尝试以下操作:
for line in p.stdout:
print("CUR", line)
and: 和:
while p.poll() is None:
line = p.stdout.read(2)
print("Print:" + line)
and: 和:
for line in iter(p.stdout.readline, b''):
print(line)
p.stdout.close()
Any idea why the code blocks on the stdout line alwayes ? 知道为什么代码总是在stdout行上阻塞吗?
UPDATE: 更新:
For example if i have the following infinite program: 例如,如果我有以下无限程序:
inf.py INF
import time
i = 0
while True:
time.sleep(0.5)
print(i)
i += 1
and the following code that runs it: 以及运行它的以下代码:
p = subprocess.Popen(r"C:\Python35\python.exe inf.py",
stdout=subprocess.PIPE, bufsize=1, universal_newlines=True)
and to generate the output I'm using one of the above methods , If i stop it using CTRL+ C it is alwayes stuck on this line: 并使用上述方法之一生成输出,如果我使用CTRL + C停止它,则始终停留在此行上:
File "C:\Python35\lib\encodings\cp1252.py", line 22, in decode
def decode(self, input, final=False):
First I set the following environment variable: PYTHONUNBUFFERED=1
首先,我设置以下环境变量:
PYTHONUNBUFFERED=1
Then I changed your code a little: 然后,我对您的代码做了一些更改:
read_infinite.py read_infinite.py
import subprocess
binary = "C:\\Python35\\python.exe"
script = "C:\\temp\\python\\tests\\inf.py"
p = subprocess.Popen([binary, script], stdout=subprocess.PIPE, bufsize=1, universal_newlines=True)
while p.poll() is None:
#line = p.stdout.read(2)
line = p.stdout.readline()
if line:
print("Result: %r" % line)
Removing bufsize=1
works same. 删除
bufsize=1
工作原理相同。
The error I got at first was that the inf.py was not found, but this was not shown, because the prints of read_infinite.py scrolled the error out. 我最初遇到的错误是没有找到inf.py,但是没有显示出来,因为read_infinite.py的打印将错误滚动了出去。 And the process stopped after a lot of lines of "Result:" (variable "line" is empty).
并且在“结果:”的许多行之后,过程停止了(变量“行”为空)。
Removing if line:
and adding time.sleep(0.5)
after the print (remember import time
!) shows the same results. if line:
删除if line:
并在打印后添加time.sleep(0.5)
(请记住import time
!),则会显示相同的结果。
So the solution is: the parent has to wait for the child. 因此解决方案是: 父母必须等待孩子。
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