How to run/interact with a Golang executable in Python?

Question

I have a command-line Golang executable on Windows named cnki-downloader.exe (open-sourced here: https://github.com/amyhaber/cnki-downloader). I want to run this executable in Python, and interact with it (get its output, then input something, then get output, and so on)

It's a command-line program, so I thought it's the same as a normal Windows command-line program built by MSVC. My code is like this:

# coding=gbk

from subprocess import Popen, PIPE

p = Popen(["cnki-downloader.exe"], stdin=PIPE, stdout=PIPE)
#p = Popen(["WlanHelper.exe"], stdin=PIPE, stdout=PIPE )

p.stdin.write( 'XXXXXX\n' )
result1 = p.stdout.read() # <---- we never return here
print result1

p.stdin.write( '1\n' )
result2 = p.stdout.read()
print result2

My Python code halts at the Popen call with cnki-downloader.exe parameter. Then I tried a C command-line program built by MSVC (named WlanHelper.exe), it runs well. My script can get the output from the exe.

So I suspect that the command-line mechanism of the Golang executable is different from a native C/C++ program, and it's difficult for other languages (like Python) to call and interact with it.

So I want to know how to interact with a Golang executable on Windows in other languages like Python?. If this is impossible, I can also consider modifying the Golang program's source code (because it's open source). But I hope I won't go that step. Thanks!

NOTE:

If possible, I want to call this Golang executable directly, instead of modifying it into a library and let Python import it. If I have to modify the Golang into a library, why not just remove the interactive manner and make everything into command-line parameters? There's no need to bother writing a Golang library. So please let's assume the Golang program is closed-sourced. I don't think there's no way for Python to call a command-line Golang program. If this is the case, then I think Golang REALLY needs to be improved in the interoperability with other languages.

Possible duplicate of Writing a Python extension in Go (Golang) — captncraig
– captncraig, Commented Oct 19, 2016 at 5:01
@captncraig I think that solution requires to compile the Golang into a library instead of the current executable. Is there a way not to change the Golang executable's source code? — hsluoyz
– hsluoyz, Commented Oct 19, 2016 at 5:14
Ah, perhaps the fact that your target app is in go is tangential to your problem. Seems there is some problem interacting with a child process from python. — captncraig
– captncraig, Commented Oct 19, 2016 at 5:48

captncraig · Accepted Answer · 2016-10-19 05:50:43Z

1

Looking at the documentation for the subprocess module you are using, it seems they have a warning about deadlocks using stdout.read() and friends:

Warning This will deadlock when using stdout=PIPE and/or stderr=PIPE and the child process generates enough output to a pipe such that it blocks waiting for the OS pipe buffer to accept more data. Use communicate() to avoid that.

So, maybe try using communicate instead?

answered Oct 19, 2016 at 5:50

captncraig

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