On 12/10/2012 12:42 PM, andrea crotti wrote:
So I implemented a simple decorator to run a function in a forked
process, as below.
It works well but the problem is that the childs end up as zombies on
one machine, while strangely
I can't reproduce the same on mine..
I know that this is not the perfect method to spawn a daemon, but I
also wanted to keep the code
as simple as possible since other people will maintain it..
What is the easiest solution to avoid the creation of zombies and
maintain this functionality?
thanks
def on_forked_process(func):
from os import fork
"""Decorator that forks the process, runs the function and gives
back control to the main process
"""
def _on_forked_process(*args, **kwargs):
pid = fork()
if pid == 0:
func(*args, **kwargs)
_exit(0)
else:
return pid
return _on_forked_process
Ou. yo need to use something more advanced. This is the code from book
('Unix Network Programing' - the python implementation)
import sys, os
def daemonize (stdin='/dev/null', stdout='/dev/null', stderr='/dev/null'):
# Perform first fork.
try:
pid = os.fork( )
if pid > 0:
sys.exit(0) # Exit first parent.
except OSError, e:
sys.stderr.write("fork #1 failed: (%d) %s\n" % (e.errno,
e.strerror))
sys.exit(1)
# Decouple from parent environment.
os.chdir("/")
os.umask(0)
os.setsid( )
# Perform second fork.
try:
pid = os.fork( )
if pid > 0:
sys.exit(0) # Exit second parent.
except OSError, e:
sys.stderr.write("fork #2 failed: (%d) %s\n" % (e.errno,
e.strerror))
sys.exit(1)
# The process is now daemonized, redirect standard file descriptors.
for f in sys.stdout, sys.stderr: f.flush( )
si = file(stdin, 'r')
so = file(stdout, 'a+')
se = file(stderr, 'a+', 0)
os.dup2(si.fileno( ), sys.stdin.fileno( ))
os.dup2(so.fileno( ), sys.stdout.fileno( ))
os.dup2(se.fileno( ), sys.stderr.fileno( ))
Put this file and named daemon.py, then just for your program by calling
import this file.
Like this.
from daemon import daemonize
def main():
while True:
print 'I'm Alive :)'
if __name__ == '__main__':
daemonize(stdout='/var/log/run_time.log', stderr='/var/log/error.log')
main()
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