Forum: JRuby The difference between JAVA_OPTS and JRUBY_OPTS

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C0cb3aadb9a66d00df16686f4a1fc312?d=identicon&s=25 Tim Uckun (Guest)
on 2013-12-04 02:23
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I would like some clarity on how to use java performance options with

It seems like there is a -J-X.... flag for the jruby which mimic the
options but I don't know which takes preference and what's the best way
deal with these options.

Normally I run things from scripts which end up constructing something

 JRUBY_OPTS="-J-XX:+TieredCompilation ..."
JAVA_OPTS="JAVA_OPTS="-noverify ..."


sometimes I just export the JRUBY_OPTS and don't include them in the
command line.

So which is the preferred way to do this? Is a .jruby directory better
either one of them?

If I have conflicting directives which one takes priority?

Why do I get a "ignored" on a bunch of my options?

Sorry my java-fu is rather weak and it seems like there really ought to
a clear way to deal with this stuff.
C0cb3aadb9a66d00df16686f4a1fc312?d=identicon&s=25 Tim Uckun (Guest)
on 2013-12-19 00:28
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Hey Guys.

Hate to bump myself but I would really appreciate some clarity about

Today I am fooling around with to torqbox the next generation of
I installed the gem and am running jruby 1.7.8

I run the torqbox command on my sample rails app (no real controllers,
a large gemfile) and it shows a running memory size of a little under
megs.  I then run the following command

/usr/bin/java -jar jruby/jruby-complete-1.7.8-with-bundler.jar
(I also tried it with a plain old jruby-complete no bundler)

and the same app now takes up almost twice as much memory (700K+).

Next I run it like this

usr/bin/java -XX:+TieredCompilation -XX:TieredStopAtLevel=1 -noverify
-Xmx500m -Xss2048k -Xcompile.invokedynamic=false
-Djruby.launch.inproc=false -jar
jruby/jruby-complete-1.7.8-with-bundler.jar bin/torqbox

And voila the memory drops again to 300+ megs

next I put this in the script

export JRUBY_OPTS="-J-XX:+TieredCompilation -J-XX:TieredStopAtLevel=1
-J-noverify  -J-Xmx500m -J-Xss2048k  -J-Xcompile.invokedynamic=false

and run the above commands WITHOUT the java opts  and voila the memory
usage is up again so the JRUBY_OPTS is completely being ignored!

Next I try this

/usr/bin/java -jar ruby/jruby-complete-1.7.8-with-bundler.jar
-J-XX:+TieredCompilation -J-XX:TieredStopAtLevel=1 -J-noverify
-J-Xss2048k -J-Xcompile.invokedynamic=false

warning: -J-XX:+TieredCompilation argument ignored (launched in same
warning: -J-XX:TieredStopAtLevel=1 argument ignored (launched in same
warning: -J-noverify argument ignored (launched in same VM?)
warning: -J-Xmx500m argument ignored (launched in same VM?)
warning: -J-Xss2048k argument ignored (launched in same VM?)
warning: -J-Xcompile.invokedynamic=false argument ignored (launched in
warning: -J-Djruby.launch.inproc=false argument ignored (launched in

and no change still large amount of memory being used.

So it looks like JRUBY_OPTS is being ignored altogether.  Can anybody
explain how JRUBY_OPTS is supposed to work.

6a22563bd5790a15adc54c8ca772eb22?d=identicon&s=25 Ben Browning (Guest)
on 2013-12-19 01:31
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This is an artifact of the way you're starting JRuby. The "-J" prefixed
JRUBY_OPTS are JVM options that have to be set before the JVM boots.
This is why your options work when passed directly to the 'java' command
and why it warns about the arguments being ignored when you set
$JRUBY_OPTS but do not use the jruby launcher (and instead use java -jar

Because you're using JRuby as a jar instead of downloading a JRuby
distribution and using its launchers, it's up to use to make sure you
set the appropriate JVM options before the JVM boots.

C0cb3aadb9a66d00df16686f4a1fc312?d=identicon&s=25 Tim Uckun (Guest)
on 2013-12-19 02:00
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So how do I pass jruby specific options to it like --1.9 and such?
6a22563bd5790a15adc54c8ca772eb22?d=identicon&s=25 Ben Browning (Guest)
on 2013-12-19 03:15
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Those options can still be passed via JRUBY_OPTS or directly on the
commandline. It's just the "-J" prefixed options that won't be supported
with "java -jar ..."

C0cb3aadb9a66d00df16686f4a1fc312?d=identicon&s=25 Tim Uckun (Guest)
on 2013-12-19 04:27
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Is there a preference as to which one I should set.

From what I can gather you can set _JAVA_OPTIONS in your environment and
you can set JRUBY_OPTS .  if I set _JAVA_OPTIONS will invoking jruby use
those options? If I set both which gets priority?

F1d37642fdaa1662ff46e4c65731e9ab?d=identicon&s=25 Charles Nutter (headius)
on 2013-12-19 14:24
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JAVA_OPTS is used by the `jruby` launcher to pass options to the JVM
as it starts. That environment variable does nothing if you use the
jruby jar directly.

JRUBY_OPTS is used by both the `jruby` launcher and JRuby itself. When
using the launcher, all command-line arguments will work as if passed
to the `jruby` command. When using the jar directly, only options
processed after the JVM starts will be honored (Ruby compat version,
etc). In this latter case, options handled only by the launcher will
not work (-Xjit.threshold=# style options, --manage, others you see
processed by bin/jruby.bash).

The -J options are processed by the JRuby launcher and used to pass
options directly to the JVM. When using the jar directly, remove the
-J and pass those options to the `java` command.

There's no real preference as to which you use. they are all provided
as convenience mechanisms for the various launch scenarios.

- Charlie
C0cb3aadb9a66d00df16686f4a1fc312?d=identicon&s=25 Tim Uckun (Guest)
on 2013-12-20 12:11
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After experimenting a bit I found that _JAVA_OPTIONS is picked up by
no matter what you are doing with it.

As far as I can tell JRUBY_OPTS don't get used if I use java -jar
jruby-complete-1.7.8.jar they do get used if I invoke ruby command.

I didn't seem to have much luck with JAVA_OPTS at all when I was calling
java -jar I didn't test them with the jruby binary.

In the end I set  both _JAVA_OPTIONS and JRUBY_OPTS in my bashrc which
covers all my use cases.

On Fri, Dec 20, 2013 at 2:22 AM, Charles Oliver Nutter
F1d37642fdaa1662ff46e4c65731e9ab?d=identicon&s=25 Charles Nutter (headius)
on 2013-12-20 13:59
(Received via mailing list)
Huh, I didn't even know _JAVA_OPTIONS existed. Given the leading
underscore, I would guess it is nonstandard, but I'm glad to hear it
for you.

- Charlie (mobile)
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