RFR [9] 8153181: Examine sun.misc.VMSupport

[Mandy Chung]

> On Apr 2, 2016, at 2:53 AM, Alan Bateman <Alan.Bateman at oracle.com> wrote:
> 
> 
> (cc'ing serviceability-dev as this is where this code is maintained).
> 
> 
>> On 02/04/2016 00:32, Mandy Chung wrote:
>> Hi Chris,
>> 
>> Would jdk.internal.vm be appropriate for this VMSupoprt class?
> I agree.
> 
>> 
>> VMSupport::getAgentProperties simply calls JVM_InitAgentProperties.  java.management could call JVM_InitAgentProperties directly.
>> 
>> src/jdk.jdwp.agent/share/native/libjdwp/util.c
>>    JDWP calls it and needs to be updated.
> If I recall correctly then this is so that the debugger transport details can be advertised. There is a process AttachingConnector that depends on that so I agree this needs to be updated.
> 
>> 
>> VMSupport.getVMTemporaryDirectory() is for jdk.jvmstat to use and I suggest to move this method to jdk.internal.perf.Perf.
> It could although I assume this means that introducing a new shared library.

jdk.internal.perf is in java.base.  Another option is to move it to jdk.jvmstat that i considered but may not worth it since perf counter is still in java.base.

Mandy 

> 
>> 
>> Mandy
>> 
>>> On Mar 31, 2016, at 9:02 AM, Chris Hegarty <chris.hegarty at oracle.com> wrote:
>>> 
>>> As part of JEP 260, all non-Critical APIs in sun.misc are being examined.
>>> 
>>> sun.misc.VMSupport is a utility class supporting two functions:
>>>  1) the initialization of management Agent properties, and
>>>  2) the retrieval of the VM temporary directory used by the attach and perf data files.
>>> 
>>> The initialization of Agent properties is used statically by the java.managment module,
>>> or can be provoked by a serviceability tool on a VM that has had an agent loaded in it.
>>> The location of VM temporary files is a low-level interface between the libraries and VM.
>>> For these reasons, VMSupport should remain in the base module, but be moved to an
>>> internal package.
>>> 
>>> http://cr.openjdk.java.net/~chegar/8153181/00/
>>> https://bugs.openjdk.java.net/browse/JDK-8153181
>>> 
>>> -Chris.
>