Please review -XshowSettings a java launcher option.

David Holmes David.Holmes at
Fri Nov 12 02:01:28 UTC 2010

Hi Kumar,

Is the purpose here to report what command-line options were used or to 
report what particular settings are in effect? If the former then you do 
not need any defaults for the "not set" case. If the latter then you 
should really defer this to the VM itself for the "VM options", because 
as it stands:

- if -Xmx is not set then Runtime.maxMemory() is not equivalent, so you 
are misleading the user (And why not report -Xms?)
- if -Xss is not set the resulting value is not an OS default but a VM 
- ServerClassMachine() does not take into account -Xint possibility (and 
will need updating for Tiered compilation)

I'd be tempted to just drop the "VM options" part of this, unless you 
are going to make a call into the VM to obtain them.


Kumar Srinivasan said the following on 11/12/10 07:56:
> Hi All,
> Please review the following:
> This will print all the known settings/properties/locales
> supported and known  to Java, this has  been a long standing request.
> A sample output attached below.
> Note: the -X option specifically is being used so we can evolve this option
> and add more useful information, in future versions of java.
> Thanks
> Kumar

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