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

[mandy chung]

On 2/13/18 1:30 AM, Harsha Wardhana B wrote:
> Hi,
>
> Please find below the revised webrev.
>
> http://cr.openjdk.java.net/~hb/8187498/webrev.02/
>
>
> On Friday 09 February 2018 05:07 AM, mandy chung wrote:
>> On 2/7/18 1:19 AM, Harsha Wardhana B wrote:
>> > 
>> > --start-management-agent will not be recognized in the current format and
>> > hence will not default to --start-management-agent=local=true.
>>
>> `--start-local-management-server` is one option as Alan suggests.
>> Another option is to make `--start-management-agent` to accept
>> an optional argument.  VM can accept `--start-management-agent`
>> or `--start-management-agent=port=1234,ssl=on`.  It may require
>> more launcher change to support it.
> Yes. It requires lot more changes to launcher. Hence optional argument 
> to --start-management-agent was not added in order to keep the 
> launcher impact minimum.

This is just one option for you to consider.   So the current proposal 
of the new option to start a remote management server, right?
>> Agent.java
>>   If --start-management-agent is set, -Dcom.sun.management.* takes
>>   precedence.  Do you really want to do that?  The new VM option
>>   intends to simplify the command-line to type in.  I think it's
>>   cleaner and reasonable if --start-management-agent is specified,
>>   -Dcom.sun.management.* are ignored (maybe worth emit a warning if set)
> We can probably document that -D options will be overridden instead of 
> emitting a warning.

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?

>>   The implementation uses VMManagement::getVmArguments and scan
>>   the VM options for -start-management-agent.  The VM is the one
>>   invoking jdk.internal.agent.Agent::startAgent.  A simpler option
>>   is to change Agent::startAgent to take an argument parameter
>>   that will be passed with the argument of --start-management-agent
>>   or null if not set.
>>
>>   Similarly for startRemoteManagementAgent and startLocalAgent_name.
> Implementing this change requires lot of changes to argument parsing 
> in native code and hence it is simpler to handle this at java layer.

Can you describe how --start-management-agent option will be used for 
jcmd and any other tool that attaches to a running VM to start the 
agent?  Example command-line will be useful.


Mandy
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