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

[Mandy Chung]

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
>> 
>> 
>>