Pidcheck is a python decorator to check and see if a process with the same PID is still running.

checkpid_test.py

#!/usr/bin/env python
from checkpid import pidcheck
from time import sleep
import logging


log = logging.getLogger("checkpid")
log.setLevel(logging.INFO)
log.setLevel(logging.DEBUG)
ch = logging.StreamHandler()
formatter = logging.Formatter("%(asctime)s - %(name)s - %(levelname)s - %(message)s")
ch.setFormatter(formatter)
log.addHandler(ch)


@pidcheck('checkpid_test.pid')
def main():
    print "made it to main()"
    sleep(15)
    print "made it past sleep()"


if __name__ == '__main__':
    print "made it to if __name__ == '__main__'"
    try:
        main()
    except:
        print "made it to last except statement"
        raise

pidcheck.py

import os
import logging
import commands

log = logging.getLogger('checkpid')


def pidcheck(pid_name, pid_file_base_dir='/tmp/'):
    """
    Pidcheck is a python decorator to check and see if a process with the same PID is still running.

    Example Usage::

        from some.path.pidcheck import pidcheck

        @pidcheck('testing_decorator.pid')
        def main():
            sleep(15)
            print "main function called"

    """
    def inner_pidcheck(func):
        def wrapper(*args, **kwargs):
            pid_file_path = os.path.join(pid_file_base_dir, pid_name)

            if os.path.exists(pid_file_path):
                f = open(pid_file_path)
                old_pid = int(f.read())
                f.close()
                log.debug("Old pid = %s" % old_pid)
                out = commands.getoutput('ps -p %s' % old_pid)
                if str(old_pid) in out:
                    log.debug("Process is still running. Exiting ...")
                    return wrapper
            else:
                new_pid = os.getpid()
                f = open(pid_file_path, 'w')
                f.write(str(os.getpid()))
                f.close()
                log.debug("New pid = %s" % new_pid)

            try:
                func(*args, **kwargs)
            except KeyboardInterrupt:
                os.remove(pid_file_path)
                print "Shutdown requested. Exiting ..."
            except:
                os.remove(pid_file_path)
                raise

            os.remove(pid_file_path)

        return wrapper
    return inner_pidcheck