I am having issues with daemons (to a process in detached from terminal)
`each_object’: ObjectSpace is disabled; each_object will only work with
Class, pass +O to enable (RuntimeError)
I am just trying to use daemons to run a process detached from the tty
(so that it will continue to run after I logout). I think I am using
daemons in the most simplistic case:
scaleMatrix itself is a jruby script. Using this under ruby e.g. using
ruby calling a ruby script, appears to work correctly (simple tests),
however this is not the case with jruby.
Is there perhaps a better way of detaching from the controlling tty and
have the process run after I log out?
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Following up on this a bit, after some experimentation, I am not getting
a nice message:
jruby -X+O scaelMatrix.rb start
`safefork’: fork is unsafe and disabled by default on JRuby
So now I am stuck. Either I need to enable an ‘unsafe’ method or I need
some help in understanding how to create a daemonized process e.g. a
process that is detached from the parent tty so that I can log out and
still have the application/process run. Any suggestions?
So now I am truly stuck. Can anyone please educate me on how to create a daemon process with Jruby? I just need to be able to launch this application/process and be able to log out and have the application/process continue to run (for several weeks). Any help is greatly appreciated!
Okay, so further testing shows that indeed, fork system call fails (or
at least I believe it fails) on my sparc machine:
jruby -X+O -J-Djruby.fork.enabled=true scaleMatrix.rb start
WARNING: fork is highly unlikely to be safe or stable on the JVM. Have
/usr/local/jruby-1.1.4/lib/ruby/gems/1.8/gems/daemons-1.0.10/lib/daemons/daemonize.rb:151:in call_as_daemon'/usr/local/jruby-1.1.4/lib/ruby/gems/1.8/gems/daemons-1.0.10/lib/daemons/daemonize.rb:151:in call_as_daemon’: No child processes - No child processes: No child
processes - No child processes (Errno::ECHILD)
So now I am truly stuck. Can anyone please educate me on how to create
a daemon process with Jruby? I just need to be able to launch this
application/process and be able to log out and have the
application/process continue to run (for several weeks). Any help is
That’s a good idea and in fact, I have tried unsuccessfully to have an
external jruby wrapper invoke the scaleMatrix jruby script, but I run
into the same problem.
Perhaps you are suggesting that I use a different language to accomplish
this? I am on the thought of writing a simple c app to setsid on the
process, but was hoping this could all be done in ruby/jruby (well ruby
actually does work).