Open code review for 8061999 Enhance VM option parsing to allow options to be specified

[Daniel D. Daugherty]

 > Ron has a detailed write-up documenting all the research that he
 > did on the various command line option mechanisms. We had planned
 > to attach that write-up to the bug report, but we dropped the ball
 > (Sorry Mary!) After Ron returns, we'll make a final editing pass
 > on the document and attach it to the bug report.

Ron has attached the following document to JDK-8061999:

ORV1.0_The_State_of_Options_Parsing_in_the_JVM.txt

That attachment should address most if not all of the historical
and architectural comments in this review thread.

Dan


On 6/24/15 10:19 AM, Daniel D. Daugherty wrote:
> On 6/23/15 10:43 PM, John Rose wrote:
>> On Jun 23, 2015, at 7:50 PM, David Holmes <david.holmes at oracle.com> 
>> wrote:
>>> On 24/06/2015 3:43 AM, Ron Durbin wrote:
>>>> David,
>>>>
>>>> The '-XX:Flags' option was considered during the research phase
>>>> of this project and was rejected because of its limitations. The
>>>> '-XX:Flags' option only works for boolean flag options and it
>>>> uses a different syntax for the options than the command line.
>>>> For example, '-XX:+UseSerialGC' would be specified as '+UseSerialGC'
>>>> in the '-XX:Flags' option file.
>>> I'm a little surprised the Flags option wasn't extended to cover 
>>> these additional requirements. But presumably it should now be 
>>> deprecated as we (again presumably) don't want to have two 
>>> mechanisms for doing this.
>> I thought the Flags option used to handle any command line options, 
>> and like David I'm surprised the right answer is to get rid of it and 
>> make a new option that does what I think the Flags option should be 
>> doing.
>>
>> — John
>
> Greetings,
>
> Ron is out of the office until next week so I'll provide a little
> bit of background...
>
> Ron has a detailed write-up documenting all the research that he
> did on the various command line option mechanisms. We had planned
> to attach that write-up to the bug report, but we dropped the ball
> (Sorry Mary!) After Ron returns, we'll make a final editing pass
> on the document and attach it to the bug report.
>
> I fleshed out the '-XX:Flags' test cases that Ron posted earlier
> in the thread:
>
> $ more flags.input.*::::::::::::::
> flags.input.boolean
> ::::::::::::::
> +UseSerialGC
> ::::::::::::::
> flags.input.ccstr
> ::::::::::::::
> ErrorFile=my_error_file
> ::::::::::::::
> flags.input.uintx
> ::::::::::::::
> MinRAMFraction=8
>
> $ java -XX:+PrintVMOptions -XX:Flags=flags.input.boolean  -version
> VM option '+UseSerialGC'
> VM option '+PrintVMOptions'
> VM option 'Flags=flags.input.boolean'
> java version "1.9.0-ea"
> Java(TM) SE Runtime Environment (build 1.9.0-ea-b69)
> Java HotSpot(TM) 64-Bit Server VM (build 1.9.0-ea-b69, mixed mode)
>
> $ java -XX:+PrintVMOptions -XX:Flags=flags.input.ccstr  -version
> VM option 'ErrorFile=my_error_file'
> VM option '+PrintVMOptions'
> VM option 'Flags=flags.input.ccstr'
> java version "1.9.0-ea"
> Java(TM) SE Runtime Environment (build 1.9.0-ea-b69)
> Java HotSpot(TM) 64-Bit Server VM (build 1.9.0-ea-b69, mixed mode)
>
> $ java -XX:+PrintVMOptions -XX:Flags=flags.input.uintx  -version
> VM option 'MinRAMFraction=8'
> VM option '+PrintVMOptions'
> VM option 'Flags=flags.input.uintx'
> java version "1.9.0-ea"
> Java(TM) SE Runtime Environment (build 1.9.0-ea-b69)
> Java HotSpot(TM) 64-Bit Server VM (build 1.9.0-ea-b69, mixed mode)
>
>
> It looks like the '-XX:Flags' option does work for 'bool', 'uintx'
> and 'ccstr' options. Clearly Ron and I didn't remember the exact
> reason that he ruled out using the '-XX:Flags' option. This part
> of the review thread will have to be resolved after Ron returns.
>
> Dan
>