Jvmargs, a sanity checker for JVM options


#1

hey folks,

i have written a little gem to parse JVM options and would love some
feedback on it. Managing JVM options in a cookbooks is a total PITA
and I hope this makes it easier. This is less than alpha quality, i am
posting it here to get some feedback, not to notify others of a
production-ready tool. I foresee it being used in Java-related
cookbooks to provide a set of application-specific defaults and then
make it easy to override or add to them in recipe code.

This library parses JVM options so that any given option is only
stored once. It does this by breaking each option into one of the
three option categories:

  1. standard, ex: -server, -enablesystemassertions
  2. nonstandard, ex: -Xmx128M, -Xint
  3. unstable, ex: -XX:-DisableExplicitGC, -XX:AltStack=128M
  4. directive, ex: -Dcom.sun.management.jmxremote

JVMArgs will ensure that only one value is stored for any given
option. Here is a quick example

args = JVMArgs::Args.new("-XX:-DisableExplicitGC", “-Xmx256M”)

“-XX:-DisableExplicitGC” is now stored in args

args.add("-XX:+DisableExplicitGC")
args.add("-Xmx2G")

the settings are now “-XX:+DisableExplicitGC” and “-Xmx2G”


#2

hey, been looking for something like this to come along, looks like a very
clean, sane way to handle it :smiley:

in your todo you have ensure min and max heap should be the same. why is
this?

i didn’t dig to far into the code, but will it support parsing a space
delimited string, as the current tomcat and tomcat6 cookbooks expect, or
will the cookbook be expected to handle that?

thanks!

On Thu, Mar 21, 2013 at 4:53 AM, Bryan Berry bryan.berry@gmail.com wrote:

hey folks,

i have written a little gem to parse JVM options and would love some
feedback on it. Managing JVM options in a cookbooks is a total PITA
and I hope this makes it easier. This is less than alpha quality, i am
posting it here to get some feedback, not to notify others of a
production-ready tool. I foresee it being used in Java-related
cookbooks to provide a set of application-specific defaults and then
make it easy to override or add to them in recipe code.

https://github.com/bryanwb/jvmargs

This library parses JVM options so that any given option is only
stored once. It does this by breaking each option into one of the
three option categories:

  1. standard, ex: -server, -enablesystemassertions
  2. nonstandard, ex: -Xmx128M, -Xint
  3. unstable, ex: -XX:-DisableExplicitGC, -XX:AltStack=128M
  4. directive, ex: -Dcom.sun.management.jmxremote

JVMArgs will ensure that only one value is stored for any given
option. Here is a quick example

args = JVMArgs::Args.new("-XX:-DisableExplicitGC", “-Xmx256M”)

“-XX:-DisableExplicitGC” is now stored in args

args.add("-XX:+DisableExplicitGC")
args.add("-Xmx2G")

the settings are now “-XX:+DisableExplicitGC” and “-Xmx2G”


#3

min and max should be the same because there is no benefit to having a
lower min according to everything I have read. It can slow down your
application startup however.

it will not support parsing a space delimited string, only the options
specifically for the JVM, for example

"java -Djava.io.tmpdir=/tmp/foo -server -Xmx256m -Xint
-XX:MaxPermSize=512M -classpath /tmp/foo.jar:/tmp/baz.jar
org.apache.catalina.Bootstrap start "

jvmargs doesn’t add the java binary to the beginning nor the
"org.apache.catalina.Bootstrap start"

I do want to handle the classpath but i have not figured out a clean
way to handle that yet :frowning:

i would very much appreciate feedback and testing. this afternoon i
hope to add support for arbitrary rules like the following

“if Max heap is greater than available RAM, raise an error”
“if Max heap is changed, also set Min heap to same value”

On Thu, Mar 21, 2013 at 2:18 PM, Jesse Campbell hikeit@gmail.com wrote:

hey, been looking for something like this to come along, looks like a very
clean, sane way to handle it :smiley:

in your todo you have ensure min and max heap should be the same. why is
this?

i didn’t dig to far into the code, but will it support parsing a space
delimited string, as the current tomcat and tomcat6 cookbooks expect, or
will the cookbook be expected to handle that?

thanks!

On Thu, Mar 21, 2013 at 4:53 AM, Bryan Berry bryan.berry@gmail.com wrote:

hey folks,

i have written a little gem to parse JVM options and would love some
feedback on it. Managing JVM options in a cookbooks is a total PITA
and I hope this makes it easier. This is less than alpha quality, i am
posting it here to get some feedback, not to notify others of a
production-ready tool. I foresee it being used in Java-related
cookbooks to provide a set of application-specific defaults and then
make it easy to override or add to them in recipe code.

https://github.com/bryanwb/jvmargs

This library parses JVM options so that any given option is only
stored once. It does this by breaking each option into one of the
three option categories:

  1. standard, ex: -server, -enablesystemassertions
  2. nonstandard, ex: -Xmx128M, -Xint
  3. unstable, ex: -XX:-DisableExplicitGC, -XX:AltStack=128M
  4. directive, ex: -Dcom.sun.management.jmxremote

JVMArgs will ensure that only one value is stored for any given
option. Here is a quick example

args = JVMArgs::Args.new("-XX:-DisableExplicitGC", “-Xmx256M”)

“-XX:-DisableExplicitGC” is now stored in args

args.add("-XX:+DisableExplicitGC")
args.add("-Xmx2G")

the settings are now “-XX:+DisableExplicitGC” and “-Xmx2G”


#4

I’ve read plenty that suggests that depending on the situation, having
different Xms and Xmx values can be beneficial.

i’ve seen things like this:
http://java-monitor.com/forum/showthread.php?t=427
which suggest that setting them the same has no particularly beneficial
effect.

and I’ve seen things like this:
http://weblogs.java.net/blog/kcpeppe/archive/2011/12/19/setting-xmx-xms-still-considered-harmful
which suggest that the ideal settings are for xms to be your 99% case, and
xmx allow for some wiggle room

in fact, i haven’t seen any really good recent analyses that support
setting them the same, just lots of rhetoric

-jesse

On Thu, Mar 21, 2013 at 9:31 AM, Bryan Berry bryan.berry@gmail.com wrote:

min and max should be the same because there is no benefit to having a
lower min according to everything I have read. It can slow down your
application startup however.

it will not support parsing a space delimited string, only the options
specifically for the JVM, for example

"java -Djava.io.tmpdir=/tmp/foo -server -Xmx256m -Xint
-XX:MaxPermSize=512M -classpath /tmp/foo.jar:/tmp/baz.jar
org.apache.catalina.Bootstrap start "

jvmargs doesn’t add the java binary to the beginning nor the
"org.apache.catalina.Bootstrap start"

I do want to handle the classpath but i have not figured out a clean
way to handle that yet :frowning:

i would very much appreciate feedback and testing. this afternoon i
hope to add support for arbitrary rules like the following

“if Max heap is greater than available RAM, raise an error”
“if Max heap is changed, also set Min heap to same value”

On Thu, Mar 21, 2013 at 2:18 PM, Jesse Campbell hikeit@gmail.com wrote:

hey, been looking for something like this to come along, looks like a
very
clean, sane way to handle it :smiley:

in your todo you have ensure min and max heap should be the same. why is
this?

i didn’t dig to far into the code, but will it support parsing a space
delimited string, as the current tomcat and tomcat6 cookbooks expect, or
will the cookbook be expected to handle that?

thanks!

On Thu, Mar 21, 2013 at 4:53 AM, Bryan Berry bryan.berry@gmail.com
wrote:

hey folks,

i have written a little gem to parse JVM options and would love some
feedback on it. Managing JVM options in a cookbooks is a total PITA
and I hope this makes it easier. This is less than alpha quality, i am
posting it here to get some feedback, not to notify others of a
production-ready tool. I foresee it being used in Java-related
cookbooks to provide a set of application-specific defaults and then
make it easy to override or add to them in recipe code.

https://github.com/bryanwb/jvmargs

This library parses JVM options so that any given option is only
stored once. It does this by breaking each option into one of the
three option categories:

  1. standard, ex: -server, -enablesystemassertions
  2. nonstandard, ex: -Xmx128M, -Xint
  3. unstable, ex: -XX:-DisableExplicitGC, -XX:AltStack=128M
  4. directive, ex: -Dcom.sun.management.jmxremote

JVMArgs will ensure that only one value is stored for any given
option. Here is a quick example

args = JVMArgs::Args.new("-XX:-DisableExplicitGC", “-Xmx256M”)

“-XX:-DisableExplicitGC” is now stored in args

args.add("-XX:+DisableExplicitGC")
args.add("-Xmx2G")

the settings are now “-XX:+DisableExplicitGC” and “-Xmx2G”


#5

well I can definitely be horribly mistaken on the matching Xmx and Xms
:slight_smile: , and am willing to change the code

iirc I read the matching Xmx and Xms in the “Java Performance” book
but I could be mistaken

On Thu, Mar 21, 2013 at 2:44 PM, Jesse Campbell hikeit@gmail.com wrote:

I’ve read plenty that suggests that depending on the situation, having
different Xms and Xmx values can be beneficial.

i’ve seen things like this:
http://java-monitor.com/forum/showthread.php?t=427
which suggest that setting them the same has no particularly beneficial
effect.

and I’ve seen things like this:
http://weblogs.java.net/blog/kcpeppe/archive/2011/12/19/setting-xmx-xms-still-considered-harmful
which suggest that the ideal settings are for xms to be your 99% case, and
xmx allow for some wiggle room

in fact, i haven’t seen any really good recent analyses that support setting
them the same, just lots of rhetoric

-jesse

On Thu, Mar 21, 2013 at 9:31 AM, Bryan Berry bryan.berry@gmail.com wrote:

min and max should be the same because there is no benefit to having a
lower min according to everything I have read. It can slow down your
application startup however.

it will not support parsing a space delimited string, only the options
specifically for the JVM, for example

"java -Djava.io.tmpdir=/tmp/foo -server -Xmx256m -Xint
-XX:MaxPermSize=512M -classpath /tmp/foo.jar:/tmp/baz.jar
org.apache.catalina.Bootstrap start "

jvmargs doesn’t add the java binary to the beginning nor the
"org.apache.catalina.Bootstrap start"

I do want to handle the classpath but i have not figured out a clean
way to handle that yet :frowning:

i would very much appreciate feedback and testing. this afternoon i
hope to add support for arbitrary rules like the following

“if Max heap is greater than available RAM, raise an error”
“if Max heap is changed, also set Min heap to same value”

On Thu, Mar 21, 2013 at 2:18 PM, Jesse Campbell hikeit@gmail.com wrote:

hey, been looking for something like this to come along, looks like a
very
clean, sane way to handle it :smiley:

in your todo you have ensure min and max heap should be the same. why is
this?

i didn’t dig to far into the code, but will it support parsing a space
delimited string, as the current tomcat and tomcat6 cookbooks expect, or
will the cookbook be expected to handle that?

thanks!

On Thu, Mar 21, 2013 at 4:53 AM, Bryan Berry bryan.berry@gmail.com
wrote:

hey folks,

i have written a little gem to parse JVM options and would love some
feedback on it. Managing JVM options in a cookbooks is a total PITA
and I hope this makes it easier. This is less than alpha quality, i am
posting it here to get some feedback, not to notify others of a
production-ready tool. I foresee it being used in Java-related
cookbooks to provide a set of application-specific defaults and then
make it easy to override or add to them in recipe code.

https://github.com/bryanwb/jvmargs

This library parses JVM options so that any given option is only
stored once. It does this by breaking each option into one of the
three option categories:

  1. standard, ex: -server, -enablesystemassertions
  2. nonstandard, ex: -Xmx128M, -Xint
  3. unstable, ex: -XX:-DisableExplicitGC, -XX:AltStack=128M
  4. directive, ex: -Dcom.sun.management.jmxremote

JVMArgs will ensure that only one value is stored for any given
option. Here is a quick example

args = JVMArgs::Args.new("-XX:-DisableExplicitGC", “-Xmx256M”)

“-XX:-DisableExplicitGC” is now stored in args

args.add("-XX:+DisableExplicitGC")
args.add("-Xmx2G")

the settings are now “-XX:+DisableExplicitGC” and “-Xmx2G”


#6

Brian,

This is very cool ! Thanks !

-John

On Thursday, March 21, 2013, Bryan Berry bryan.berry@gmail.com wrote:

min and max should be the same because there is no benefit to having a
lower min according to everything I have read. It can slow down your
application startup however.

it will not support parsing a space delimited string, only the options
specifically for the JVM, for example

"java -Djava.io.tmpdir=/tmp/foo -server -Xmx256m -Xint
-XX:MaxPermSize=512M -classpath /tmp/foo.jar:/tmp/baz.jar
org.apache.catalina.Bootstrap start "

jvmargs doesn’t add the java binary to the beginning nor the
"org.apache.catalina.Bootstrap start"

I do want to handle the classpath but i have not figured out a clean
way to handle that yet :frowning:

i would very much appreciate feedback and testing. this afternoon i
hope to add support for arbitrary rules like the following

“if Max heap is greater than available RAM, raise an error”
“if Max heap is changed, also set Min heap to same value”

On Thu, Mar 21, 2013 at 2:18 PM, Jesse Campbell hikeit@gmail.com wrote:

hey, been looking for something like this to come along, looks like a
very

clean, sane way to handle it :smiley:

in your todo you have ensure min and max heap should be the same. why is
this?

i didn’t dig to far into the code, but will it support parsing a space
delimited string, as the current tomcat and tomcat6 cookbooks expect, or
will the cookbook be expected to handle that?

thanks!

On Thu, Mar 21, 2013 at 4:53 AM, Bryan Berry bryan.berry@gmail.com
wrote:

hey folks,

i have written a little gem to parse JVM options and would love some
feedback on it. Managing JVM options in a cookbooks is a total PITA
and I hope this makes it easier. This is less than alpha quality, i am
posting it here to get some feedback, not to notify others of a
production-ready tool. I foresee it being used in Java-related
cookbooks to provide a set of application-specific defaults and then
make it easy to override or add to them in recipe code.

https://github.com/bryanwb/jvmargs

This library parses JVM options so that any given option is only
stored once. It does this by breaking each option into one of the
three option categories:

  1. standard, ex: -server, -enablesystemassertions
  2. nonstandard, ex: -Xmx128M, -Xint
  3. unstable, ex: -XX:-DisableExplicitGC, -XX:AltStack=128M
  4. directive, ex: -Dcom.sun.management.jmxremote

JVMArgs will ensure that only one value is stored for any given
option. Here is a quick example

args = JVMArgs::Args.new("-XX:-DisableExplicitGC", “-Xmx256M”)

“-XX:-DisableExplicitGC” is now stored in args

args.add("-XX:+DisableExplicitGC")
args.add("-Xmx2G")

the settings are now “-XX:+DisableExplicitGC” and “-Xmx2G”


#7

Here’s the logic I’ve always used:

  • Set an Xmx almost always. I would rather the process take a dump
    than take the system down with it.

  • If you know you average a certain amount of memory usage after
    running for a while, set that to your Xms. Reasoning being that the
    startup hit is less painful than memory allocation on demand. Priming
    the pump and all that.

  • If you have competing jvms, all bets are off. Just size them as best you can.

As a general practice I usually set Xmx and Xms the same. There are
valid reasons, however ,that you might not want to do that such as GC
pressure and abuse of ProcessBuilder but like I said above, I’d rather
give the process the memory I know it will need at peak (if possible)
and avoid allocation issues.

JVM tuning lends itself heavily to cargo culting and really the only
safe thing to do out of the gate is set an Xmx so that you don’t tank
the system and profile (JMX for instance) while you learn the
operating pattern.

On Thu, Mar 21, 2013 at 1:44 PM, Jesse Campbell hikeit@gmail.com wrote:

I’ve read plenty that suggests that depending on the situation, having
different Xms and Xmx values can be beneficial.

i’ve seen things like this:
http://java-monitor.com/forum/showthread.php?t=427
which suggest that setting them the same has no particularly beneficial
effect.

and I’ve seen things like this:
http://weblogs.java.net/blog/kcpeppe/archive/2011/12/19/setting-xmx-xms-still-considered-harmful
which suggest that the ideal settings are for xms to be your 99% case, and
xmx allow for some wiggle room

in fact, i haven’t seen any really good recent analyses that support setting
them the same, just lots of rhetoric

-jesse

On Thu, Mar 21, 2013 at 9:31 AM, Bryan Berry bryan.berry@gmail.com wrote:

min and max should be the same because there is no benefit to having a
lower min according to everything I have read. It can slow down your
application startup however.

it will not support parsing a space delimited string, only the options
specifically for the JVM, for example

"java -Djava.io.tmpdir=/tmp/foo -server -Xmx256m -Xint
-XX:MaxPermSize=512M -classpath /tmp/foo.jar:/tmp/baz.jar
org.apache.catalina.Bootstrap start "

jvmargs doesn’t add the java binary to the beginning nor the
"org.apache.catalina.Bootstrap start"

I do want to handle the classpath but i have not figured out a clean
way to handle that yet :frowning:

i would very much appreciate feedback and testing. this afternoon i
hope to add support for arbitrary rules like the following

“if Max heap is greater than available RAM, raise an error”
“if Max heap is changed, also set Min heap to same value”

On Thu, Mar 21, 2013 at 2:18 PM, Jesse Campbell hikeit@gmail.com wrote:

hey, been looking for something like this to come along, looks like a
very
clean, sane way to handle it :smiley:

in your todo you have ensure min and max heap should be the same. why is
this?

i didn’t dig to far into the code, but will it support parsing a space
delimited string, as the current tomcat and tomcat6 cookbooks expect, or
will the cookbook be expected to handle that?

thanks!

On Thu, Mar 21, 2013 at 4:53 AM, Bryan Berry bryan.berry@gmail.com
wrote:

hey folks,

i have written a little gem to parse JVM options and would love some
feedback on it. Managing JVM options in a cookbooks is a total PITA
and I hope this makes it easier. This is less than alpha quality, i am
posting it here to get some feedback, not to notify others of a
production-ready tool. I foresee it being used in Java-related
cookbooks to provide a set of application-specific defaults and then
make it easy to override or add to them in recipe code.

https://github.com/bryanwb/jvmargs

This library parses JVM options so that any given option is only
stored once. It does this by breaking each option into one of the
three option categories:

  1. standard, ex: -server, -enablesystemassertions
  2. nonstandard, ex: -Xmx128M, -Xint
  3. unstable, ex: -XX:-DisableExplicitGC, -XX:AltStack=128M
  4. directive, ex: -Dcom.sun.management.jmxremote

JVMArgs will ensure that only one value is stored for any given
option. Here is a quick example

args = JVMArgs::Args.new("-XX:-DisableExplicitGC", “-Xmx256M”)

“-XX:-DisableExplicitGC” is now stored in args

args.add("-XX:+DisableExplicitGC")
args.add("-Xmx2G")

the settings are now “-XX:+DisableExplicitGC” and “-Xmx2G”


#8

Even if it is true - no need to force it. Have a happy path that does what you say, and a “no really” path. :slight_smile:

Adam

-----Original Message-----
From: Bryan Berry [mailto:bryan.berry@gmail.com]
Sent: Thursday, March 21, 2013 6:49 AM
To: chef@lists.opscode.com
Subject: [chef] Re: Re: Re: Re: [ANN] jvmargs, a sanity checker for JVM options

well I can definitely be horribly mistaken on the matching Xmx and Xms
:slight_smile: , and am willing to change the code

iirc I read the matching Xmx and Xms in the “Java Performance” book but I could be mistaken

On Thu, Mar 21, 2013 at 2:44 PM, Jesse Campbell hikeit@gmail.com wrote:

I’ve read plenty that suggests that depending on the situation, having
different Xms and Xmx values can be beneficial.

i’ve seen things like this:
http://java-monitor.com/forum/showthread.php?t=427
which suggest that setting them the same has no particularly
beneficial effect.

and I’ve seen things like this:
http://weblogs.java.net/blog/kcpeppe/archive/2011/12/19/setting-xmx-xm
s-still-considered-harmful which suggest that the ideal settings are
for xms to be your 99% case, and xmx allow for some wiggle room

in fact, i haven’t seen any really good recent analyses that support
setting them the same, just lots of rhetoric

-jesse

On Thu, Mar 21, 2013 at 9:31 AM, Bryan Berry bryan.berry@gmail.com wrote:

min and max should be the same because there is no benefit to having
a lower min according to everything I have read. It can slow down
your application startup however.

it will not support parsing a space delimited string, only the
options specifically for the JVM, for example

"java -Djava.io.tmpdir=/tmp/foo -server -Xmx256m -Xint
-XX:MaxPermSize=512M -classpath /tmp/foo.jar:/tmp/baz.jar
org.apache.catalina.Bootstrap start "

jvmargs doesn’t add the java binary to the beginning nor the
"org.apache.catalina.Bootstrap start"

I do want to handle the classpath but i have not figured out a clean
way to handle that yet :frowning:

i would very much appreciate feedback and testing. this afternoon i
hope to add support for arbitrary rules like the following

“if Max heap is greater than available RAM, raise an error”
“if Max heap is changed, also set Min heap to same value”

On Thu, Mar 21, 2013 at 2:18 PM, Jesse Campbell hikeit@gmail.com wrote:

hey, been looking for something like this to come along, looks like
a very clean, sane way to handle it :smiley:

in your todo you have ensure min and max heap should be the same.
why is this?

i didn’t dig to far into the code, but will it support parsing a
space delimited string, as the current tomcat and tomcat6 cookbooks
expect, or will the cookbook be expected to handle that?

thanks!

On Thu, Mar 21, 2013 at 4:53 AM, Bryan Berry
bryan.berry@gmail.com
wrote:

hey folks,

i have written a little gem to parse JVM options and would love
some feedback on it. Managing JVM options in a cookbooks is a
total PITA and I hope this makes it easier. This is less than
alpha quality, i am posting it here to get some feedback, not to
notify others of a production-ready tool. I foresee it being used
in Java-related cookbooks to provide a set of application-specific
defaults and then make it easy to override or add to them in recipe code.

https://github.com/bryanwb/jvmargs

This library parses JVM options so that any given option is only
stored once. It does this by breaking each option into one of the
three option categories:

  1. standard, ex: -server, -enablesystemassertions 2. nonstandard,
    ex: -Xmx128M, -Xint 3. unstable, ex: -XX:-DisableExplicitGC,
    -XX:AltStack=128M 4. directive, ex: -Dcom.sun.management.jmxremote

JVMArgs will ensure that only one value is stored for any given
option. Here is a quick example

args = JVMArgs::Args.new("-XX:-DisableExplicitGC", “-Xmx256M”) #
"-XX:-DisableExplicitGC" is now stored in args
args.add("-XX:+DisableExplicitGC")
args.add("-Xmx2G")

the settings are now “-XX:+DisableExplicitGC” and “-Xmx2G”