Review Request JDK-8136930 Examine implications for custom launchers, equivalent of java -X options in particular

[Mandy Chung]

I see your point.  jlink currently creates a script that calls the java launcher to run a module with main class.   None of the module options is needed in launching a modular app that is linked in the image.   -J option or like would be needed when the user wants to alter the startup option in launching such modular app.  This ability should be considered when jlink creates a custom launcher in the future.

Mandy

> On Jun 4, 2016, at 9:46 AM, forax at univ-mlv.fr wrote:
> 
> Hi Alan, hi Mandy,
> thanks for your answers,
> by 'custom launcher', i was thinking about the launchers created by jlink, this one need a -J like option, not a JNI invoked piece of C.
> 
> cheers,
> Rémi
> 
> ----- Mail original -----
>> De: "Mandy Chung" <mandy.chung at oracle.com>
>> À: "Remi Forax" <forax at univ-mlv.fr>
>> Cc: "jigsaw-dev" <jigsaw-dev at openjdk.java.net>, "hotspot-runtime-dev" <hotspot-runtime-dev at openjdk.java.net>
>> Envoyé: Samedi 4 Juin 2016 17:31:02
>> Objet: Re: Review Request JDK-8136930 Examine implications for custom launchers,	equivalent of java -X options in
>> particular
>> 
>> As Alan replied, custom launchers create a VM using the JNI invocation API
>> specifying the VM options properly and no need to set -J.  -J is a way JDK
>> launchers to pass options to the runtime environment.
>> 
>> Mandy
>> 
>>> On Jun 4, 2016, at 4:10 AM, Remi Forax <forax at univ-mlv.fr> wrote:
>>> 
>>> Hi Mandy,
>>> did you think about using -J for specifying either VM options or module
>>> options (the user really don't care) for custom launchers like we use -J
>>> to specify VM option to javac ?
>>> 
>>> cheers,
>>> Rémi
>>> 
>>> ----- Mail original -----
>>>> De: "Mandy Chung" <mandy.chung at oracle.com>
>>>> À: "jigsaw-dev" <jigsaw-dev at openjdk.java.net>, "hotspot-runtime-dev"
>>>> <hotspot-runtime-dev at openjdk.java.net>
>>>> Envoyé: Samedi 4 Juin 2016 08:47:37
>>>> Objet: Review Request JDK-8136930 Examine implications for custom
>>>> launchers,    equivalent of java -X options in
>>>> particular
>>>> 
>>>> Webrev:
>>>> http://cr.openjdk.java.net/~mchung/jdk9/webrevs/8136930/webrev.00/
>>>> 
>>>> -modulepath, -addmods, -limitmods, -XaddExports, -XaddReads, -Xpatch are
>>>> java
>>>> launcher options in the current implementation.  Custom launchers will
>>>> have
>>>> to use -D to set some system properties to configure module system.
>>>> Different ways to configure module system is confusing and not friendly
>>>> for
>>>> environments using both java launcher and custom launchers.
>>>> 
>>>> This patch pushes the handling of the module options into the VM.  That
>>>> will
>>>> avoid the confusion between launcher and VM options and avoids needing to
>>>> use system properties.  All launcher implementations can configure the
>>>> module system via JNI Invocation API setting these options in a unified
>>>> way.
>>>> The options and syntax remain the same as specified in JEP 261.
>>>> 
>>>> For the non-repeating options, like the other VM options, the last one
>>>> wins.
>>>> The current implementation communicates the options to the module system
>>>> through system properties, as a private interface, and these system
>>>> properties will be removed once they are read during the module system
>>>> initialization.  These system properties are reserved as private interface
>>>> and they will be ignored if they are set via -D in the command line.
>>>> Harold
>>>> implements the hotspot change and can explain further details.
>>>> 
>>>> This patch will impact existing tests and scripts that set the system
>>>> properties for example to break encapsulation in the command line e.g.
>>>> -Djdk.launcher.addexports.<N>.  They will need to be updated to replace
>>>> the
>>>> use of -D with the appropriate module option e.g. -XaddExports.  Since
>>>> they
>>>> are new options in JDK 9, use -XX:+IgnoreUnrecognizedVMOptions if they
>>>> need
>>>> to be ignored by earlier releases.
>>>> 
>>>> Mandy
>>>> 
>>>> 
>>>> 
>> 
>>