Add an --ontop arg to keep the process alive for heroku

[joshco]

when using daemonized DJ workers, heroku needs the parent process to stay alive. Otherwise, when it exits, the dyno will terminate, killing the workers.
This change adds --ontop to the command line options. It passed the :ontop parameter to the Daemonize call when set.

@dgobaud
Relates to issue #565 #615

[coveralls]

Coverage decreased (-0.17%) when pulling ca3f604 on joshco:master into c85a4fe on collectiveidea:master.

[coveralls]

Coverage decreased (-0.17%) when pulling f92dde4 on joshco:master into c85a4fe on collectiveidea:master.

[coveralls]

Coverage decreased (-0.17%) when pulling f92dde4 on joshco:master into c85a4fe on collectiveidea:master.

[albus522]

--ontop is the same as using run instead of start. -n N will not work the way you think it will. Instead of forking the specified number of workers, 1 worker will run and every time SIGINT occurs the worker will reset, not restart, and start working again until N SIGINT's have been received then it will finally exit.

[joshco]

You are correct. It behaves exactly as you describe. I guess what I'd need to do is only 'ontop' the last worker to be started to keep the whole thing from going away in heroku.
Do you have any recommendation for using this on heroku?

[joshco]

Right now what I'm doing is using the standard issue delayed_job with this script on heroku
basically spawn n-1 background jobs then run the last one in the foreground.
The only glitch is that I lose stdout logging from the background jobs.
I can get by with what DJ web shows me.

#!/usr/bin/env bash

COUNT=`expr $DJ_DAEMONS - 1`
# dj spawner
echo "Total: $DJ_DAEMONS Starting $COUNT jobs"
bundle exec bin/delayed_job --queue=matching -n $COUNT start
echo "starting parent"
QUEUE=matching bundle exec rake jobs:work

[albus522]

This #615 is in the works, but I haven't had the chance to polish the rough edges

[dgobaud]

Loss of logging is why I went with the solution in #615. I think I tried to fix logging by redirecting stdout/stderr etc from the child processes to the parent but I couldn't get it to work and don't remember why.