Python Send SIGINT Signal Subprocess On Windows

Question

I have readed so many questions on stackoverflow but they are too old and not helpful for me. I have a subprocess and want to send CTRL_C_EVENT Signal to stop it. I don't want to kill it directly. Here is my code :

import subprocess
import os
import signal

CREATE_NO_WINDOW = 0x08000000
'''
I tried these too but i failed.
creationflags=CREATE_NO_WINDOW | CREATE_NEW_PROCESS_GROUP | DETACHED_PROCESS
CREATE_NEW_PROCESS_GROUP = 0x00000200
DETACHED_PROCESS = 0x00000008
'''

cmd = 'my cmd arguments'
process = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.STDOUT,universal_newlines=True,shell=True,creationflags=CREATE_NO_WINDOW)
test = 0
for line in process.stdout:
    test += 1
    if (test > 60):
        os.kill(process.pid, signal.CTRL_C_EVENT)
        #This fails too
        #process.send_signal(signal.CTRL_C_EVENT)
    else:
        print(line)

Here exception :

OSError: [WinError 6] The handler is invalid

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "C:\Users\xxxxxxx\Desktop\xxxxx\test subprocess.py", line 16, in <module>
    os.kill(process.pid, signal.CTRL_C_EVENT)
SystemError: <built-in function kill> returned a result with an error set

score 0 · Answer 1 · answered Jun 15 '18 at 15:30

I expect that is because your process is still in use due to the for line in process.stdout:

You may have to exit the for loop first, then send CTRL_C_EVENT Signal to stop it

Try something like that:

import subprocess
import os
import signal

CREATE_NO_WINDOW = 0x08000000
'''
I tried these too but i failed.
creationflags=CREATE_NO_WINDOW | CREATE_NEW_PROCESS_GROUP | DETACHED_PROCESS
CREATE_NEW_PROCESS_GROUP = 0x00000200
DETACHED_PROCESS = 0x00000008
'''

cmd = 'my cmd arguments'
process = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.STDOUT,universal_newlines=True,shell=True,creationflags=CREATE_NO_WINDOW)
test = 0

CTRL_C_EVENT_is_required=False

for line in process.stdout:
    test += 1
    if (test > 60):
        CTRL_C_EVENT_is_required=True
        break
    else:
        print(line)

if CTRL_C_EVENT_is_required==True:
    os.kill(process.pid, signal.CTRL_C_EVENT)

I'm still getting same error. I tried time.sleep(20) and send os.kill ctrl_cl_event signal too but same result. — sword1st, Jun 15 '18 at 17:15

Python Send SIGINT Signal Subprocess On Windows

1 Answers1