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

[Chris Hegarty]

Updated webrev, as per comments:
  http://cr.openjdk.java.net/~chegar/8153181/01/

getVMTemporaryDirectory could be moved into jdk.internal.perf.Perf, which
would move its native implementation into the VM, perf.cpp, but it doesn’t
seem worth it, unless future refactoring wanted to get rid of
JVM_GetTemporaryDirectory.

-Chris.


On 2 Apr 2016, at 20:34, Mandy Chung <mandy.chung at oracle.com> wrote:

>> 
>> 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.