def synchronized(lock):

    """ Synchronization decorator. """

    def wrap(f):

        def newFunction(*args, **kw):

            lock.acquire()

            try:

                return f(*args, **kw)

            finally:

                lock.release()

        return newFunction

    return wrap

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())