Daemons


#1

Hello!

I am having issues with daemons (to a process in detached from terminal)
as in:

/usr/local/jruby-1.1.4/lib/ruby/gems/1.8/gems/daemons-1.0.10/lib/daemons/daemonize.rb:122:in
`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:

cat daemonize.rb
#!/usr/bin/env jruby

require ‘rubygems’
require ‘daemons’

Daemons.run(‘scaleMatrix.rb’)

end

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?

TIA!
Phy


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#2

Following up on this a bit, after some experimentation, I am not getting
a nice message:

jruby -X+O scaelMatrix.rb start
/usr/local/jruby-1.1.4/lib/ruby/gems/1.8/gems/daemons-1.0.10/lib/daemons/daemonize.rb:103:in
`safefork’: fork is unsafe and disabled by default on JRuby
(NotImplementedError)

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?

Thanks for the help!
Phy

— On Mon, 10/20/08, Phy P. removed_email_address@domain.invalid wrote:

`each_object’: ObjectSpace is disabled; each_object will

correctly (simple tests), however this is not the case with
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#3

On Mon, Oct 20, 2008 at 12:56 PM, Phy P. removed_email_address@domain.invalid
wrote:

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!

To: removed_email_address@domain.invalid
how to create a daemonized process e.g. a process that is

From: Phy P. removed_email_address@domain.invalid
/usr/local/jruby-1.1.4/lib/ruby/gems/1.8/gems/daemons-1.0.10/lib/daemons/daemonize.rb:122:in
case:

controlling tty and have the process run after I log
out?

TIA!
Phy

You will likely have more luck with this posting to the JRuby-User list.

Michael G.


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#4

Hello again.

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
fun!
/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:incall_as_daemon’: No child processes - No child processes: No child
processes - No child processes (Errno::ECHILD)
(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
greatly appreciated!

Cheers,
Phy

— On Mon, 10/20/08, Phy P. removed_email_address@domain.invalid wrote:

— On Mon, 10/20/08, Phy P.

from terminal) as in:
from the tty (so that it will continue to run after I
Daemons.run(‘scaleMatrix.rb’)
jruby.
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#5

On Mon, Oct 20, 2008 at 1:48 PM, Phy P. removed_email_address@domain.invalid wrote:

Micheal,

Opps, I thought I had posted to that group. Sorry for the junk email and thanks for the correction!

Cheers,
Phy

Actually my mistake. You had initially posted to ruby-talk and then
to JRuby-User. It was showing up under both labels in my inbox.

Sorry for the interruption, my mistake.

Michael G.


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#6

Well, you did point out that I did indeed post to the wrong mailing
list. So thanks for forcing me to verify that I had indeed published it
correctly the second time.

Cheers!
Phy

— On Mon, 10/20/08, Michael G. removed_email_address@domain.invalid wrote:

Michael G.


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#7

Just a wild guess, but would it be possible to daemonize the Java
process that you are running in?

Phy P. wrote:

`safefork’: fork is unsafe and disabled by default on

`each_object’: ObjectSpace is disabled;
from the tty (so that it will continue to run after I

Is there perhaps a better way of detaching from the

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#8

Micheal,

Opps, I thought I had posted to that group. Sorry for the junk email
and thanks for the correction!

Cheers,
Phy

— On Mon, 10/20/08, Michael G. removed_email_address@domain.invalid wrote:

sparc machine:
(Errno::ECHILD)

Phy

Following up on this a bit, after some
‘unsafe’ method or I need some help in

I am having issues with daemons (to a process
(RuntimeError)

case:

jruby.

You will likely have more luck with this posting to the
JRuby-User list.

Michael G.


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#9

Jacob,

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).

Any thoughts?

— On Mon, 10/20/08, Jacob K. removed_email_address@domain.invalid wrote:

to be able to launch this application/process and be able to

that is

removed_email_address@domain.invalid wrote:

cat daemonize.rb
scaleMatrix itself is a jruby script. Using
the case

out?

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