import multiprocessing import os import platform import sys from subprocess import PIPE from subprocess import Popen import atexit import traceback import logging import signal CREATE_NEW_PROCESS_GROUP = 0x00000200 DETACHED_PROCESS = 0x00000008 REGISTERED = [] def start_detached(executable, *args): """ Starts a fully independent subprocess (with no parent) :param executable: executable :param args: arguments to the executable, eg: ['--param1_key=param1_val', '-vvv' ...] :return: pid of the grandchild process """ # create pipe reader, writer = multiprocessing.Pipe(False) # do not keep reference multiprocessing.Process(target=_start_detached, args=(executable, *args), kwargs={'writer': writer}, daemon=True).start() # receive pid from pipe pid = reader.recv() REGISTERED.append(pid) # close pipes writer.close() reader.close() return pid def _start_detached(executable, *args, writer: multiprocessing.Pipe = None): # configure launch kwargs = {} if platform.system() == 'Windows': kwargs.update(creationflags=DETACHED_PROCESS | CREATE_NEW_PROCESS_GROUP) elif sys.version_info < (3, 2): # assume posix kwargs.update(preexec_fn=os.setsid) else: # Python 3.2+ and Unix kwargs.update(start_new_session=True) # run p = Popen([executable, *args], stdin=PIPE, stdout=PIPE, stderr=PIPE, **kwargs) # send pid to pipe writer.send(p.pid) sys.exit() def _cleanup(): for pid in REGISTERED: try: logging.getLogger(__name__).debug('cleaning up pid %d ' % pid) os.kill(pid, signal.SIGTERM) except: # noqa pass atexit.register(_cleanup)