Keep a subprocess alive?

Asked Sep 09 '16 at 07:55

Active Sep 09 '16 at 08:22

Viewed 1,056 times

I'm trying to use subprocess to open another process which should be alive while my main process is running. This main process would send some commands to that subprocess. However, when i use a pipe to communicate with that subprocess it also adds an eot(End Of Transmission) char, which is usually terminating char for processes in linux based os.

my_subprocess = subprocess.Popen("python", shell=True, stdin=subprocess.PIPE, stdout=subprocess.PIPE)
my_subprocess.stdin.write("print 2+2\n")
stdout, stderr = my_file.communicate()
my_subprocess.stdin.write("print 3+5\n")

The first call generates a ^D, which is a termination char for python shell. Therefore, i get an error like this:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: I/O operation on closed file

Is there a way to use subprocess for this purpose?

edited Sep 09 '16 at 08:22

asked Sep 09 '16 at 07:55

zorkaya

if it is to send python commands, why don't you use the built-in `eval` ? would save a lot of trouble. – Jean-François Fabre Sep 09 '16 at 08:09
because this subprocess is not python. it is just a sample usage for you to understand. – zorkaya Sep 09 '16 at 08:10
What is `my_file`? – martineau Sep 09 '16 at 08:14
it was a typo. i've corrected it. – zorkaya Sep 09 '16 at 08:23
Maybe it's simpler with a subprocess that does handles I/O simply. I think python interpreter has a lot of kludges built-in: not the easiest process to communicate with. – Jean-François Fabre Sep 09 '16 at 08:37
Actually i'm trying to communicate with spark-shell. However, the result, i mean problem, is same with the python-shell. Therefore i gave the python example. If i can't find any solution, i will write my own socket between them. – zorkaya Sep 09 '16 at 11:27

Keep a subprocess alive?

0 Answers0