OSError: [Errno 1] Operation not permitted - Python - ruby

Question

I have an automation tool that starts a Ruby on Rails server using the command line:
from subprocess import Popen
devnull = open(os.devnull, 'r+')
self.webserver = Popen(server_cmd, shell=True, stdin=devnull, stdout=devnull,
stderr=devnull, close_fds=True, preexec_fn=os.setsid)
The webserver is a process that contains the server running as a separate process (the way it is supposed to be). So I have the stop_webserver method to kill the process and stop the Rails server:
def stop_webserver(self):
"""
Stop the Rails server, if there is one running or it was created.
Kill the process and all of its children, in order to avoid having a
zoombie processes.
"""
if self.webserver is None:
self.log.info("Server isn't running. Nothing to do.")
return
if self.is_server_running():
# os.killpg(self.webserver.pid, signal.SIGTERM)
self.log.info("PID: %s" % self.webserver.pid)
# self.log.info("PID: %s" % os.getpgid(self.webserver.pid))
time.sleep(10)
os.killpg(self.webserver.pid, signal.SIGKILL)
self.webserver = None
self.log.info("Server was stopped.")
However I'm always getting the following error:
Traceback (most recent call last):
File "unit/front_end_test.py", line 27, in runTest
frontend.stop_webserver()
File "front_end.py", line 184, in stop_webserver
os.killpg(self.webserver.pid, signal.SIGKILL)
OSError: [Errno 1] Operation not permitted
If I try to terminate the process using os.getpgid I get a different error:
Traceback (most recent call last):
File "unit/front_end_test.py", line 27, in runTest
frontend.stop_webserver()
File "front_end.py", line 182, in stop_webserver
self.log.info("PID: %s" % os.getpgid(self.webserver.pid))
OSError: [Errno 3] No such process
However, the server is still running at port 3001. The process was never killed. How can I properly terminate the process?

Answer 1

I solved the problem by forcing a os.system() kill:
def stop_webserver(self):
"""
Stop the Rails server, if there is one running or it was created.
Kill the process and all of its children, in order to avoid having a
zoombie processes.
"""
if self.webserver is None:
self.log.info("Server isn't running. Nothing to do.")
return
if self.is_server_running():
try:
# os.killpg(self.webserver.pid, signal.SIGKILL)
os.killpg(self.webserver.pid, signal.SIGTERM)
self.webserver = None
self.log.info("Server was stopped.")
except OSError, e:
self.log.exception(e)
self.log.info("PID: %s" % self.webserver.pid)
os.system("sudo kill %s" % (self.webserver.pid, ))