RFR: JDK-8187498: Add a -Xmanagement flag as syntactic sugar for -Dcom.sun.management.jmxremote.* properties

[Roger Riggs]

Hi,

I'm a bit leary of command line arguments being special cased and the 
corresponding custom
mappings to system properties.   The convenience is fine but we need to 
keep the handling
out of native code so it is easier to maintain.  We don't have a Java 
API for processing
(VM) command line arguments so they are being shoehorned into properties.

$.02, Roger

On 2/21/2018 12:55 AM, Harsha Wardhana B wrote:
>
>
> On Wednesday 21 February 2018 01:51 AM, mandy chung wrote:
>> The code review and CSR review can be in parallel.  For this case,
>> I agree with Kumar to have CSR written that would help the code
>> review. Please specify the behavior and its relationship with
>> jcmd and other relevant diagnosability tools.
> ok.
>>
>> On 2/20/18 6:41 AM, Kumar Srinivasan wrote:
>>>
>>>>>> What is the behavior when 
>>>>>> -Dcom.sun.management.jmxremote.port=1234 --start-management-agent 
>>>>>> port=2345 -Dcom.sun.management.jmxremote.port=3456?
>>>>>>
>>>>>> What is the value of the system property 
>>>>>> com.sun.management.jmxremote.port at runtime?  What port number 
>>>>>> does the management server start with?
>>>>> As said earlier, values set via new flags override values set by 
>>>>> -D flags. So 2345 will be the value of 
>>>>> com.sun.management.jmxremote.port. Added a test case to validate 
>>>>> that.
>>
>> VM options are the last one wins if same option specified multiple 
>> times.  In this case, it could cause confusion (the last -D option 
>> sets the value to 3456 but it's set to a different value).
>>
>> Why not taking the simplest approach - when --start-management-agent 
>> is set, it does not accept mixing the old way (i.e. does not accept 
>> the management properties to be set via -D)?   This RFE is to make 
>> the command-line simpler and ease-of-use.  I don't see any downside 
>> to migrate entirely to the new form.
> We cannot get rid of specifying options via -D. We have plenty of -D 
> flags but very few have short-hand alternative via 
> --start-management-agent. If management properties are specified by 
> --start-management-agent, the options specified by -D are anyway 
> overwritten if specified.
>>
>> Mandy
> Harsha