Should some JDK system properties be read only ?

Seán Coffey sean.coffey at
Thu Dec 4 16:21:40 UTC 2014

On 04/12/2014 16:00, David M. Lloyd wrote:
> On 12/04/2014 09:42 AM, Seán Coffey wrote:
>> Apologies if this has been raised in past. I've run into issues in the
>> past where bad user code (app server) has set the java.home system
>> property to a value other than the default. This has consequences for
>> apps/code that depend heavily on java.home returning the correct
>> location. The case I saw was a JDK 7 runtime attempting to load JDK 6
>> config files (since java.home was pointing to JDK 6)
>> It leads me to question on whether we should change this behaviour.
>> There are a whole bunch of properties that make no sense to change.
>> Those like : java.version, java.vendor, java.home,
>> java.vm.specification.version, java.vm.specification.vendor,
>>, java.vm.version, java.vm.vendor,
>>, java.specification.version, java.specification.vendor,
>> Should we consider making them read only for JDK 9 and later ?
> Won't work unless you fundamentally change how System.setProperties() 
> works.  Right now it will accept a user-created Properties instance 
> and install it as the global system properties map.
Some code change necessary but not much AFAIK. We can detect when JDK 
read-only values are (passed in && don't match orig. value) and throw an 
Exception or fail silently. Obviously a behavioural change which would 
require spec update.


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