import multiprocessing
import os
import psutil
import signal

def target():
    while True:
        pass

proc = multiprocessing.Process(target=target)
proc.start()

print("alive \t exists")
print("%s \t %s" % (proc.is_alive(), psutil.pid_exists(proc.pid)))
os.kill(proc.pid, signal.SIGTERM)
print("%s \t %s" % (proc.is_alive(), psutil.pid_exists(proc.pid)))
proc.join()

# Output from 2.7.5 and 3.5.2 under Windows:
# alive    exists
# True     True
# True     False