RFR (S): 8204668: Cleanup management of the java.vm.info System property

[David Holmes]

Thanks Robbin!

David

On 12/06/2018 9:51 PM, Robbin Ehn wrote:
> Hi David, looks good, thanks for fixing!
> 
> /Robbin
> 
> On 06/12/2018 11:56 AM, David Holmes wrote:
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8204668
>> webrev: http://cr.openjdk.java.net/~dholmes/8204668/webrev/
>>
>> JDK-8203329 fixed a problem where the native system property for the 
>> vm.info string was not updated after argument parsing, resulting in 
>> JVM TI reporting an incorrect value.
>>
>> Looking at the overall approach for this property it can be simplified 
>> quite a bit. The basic issue is that it is initialized early in VM 
>> startup (so it can be present for crash logs) before argument parsing, 
>> but some details can change due to argument parsing. If we update the 
>> native value immediately after argument parsing, and so before the 
>> properties are passed through to the Java side, then we don't need to 
>> execute the Java code in reset_vm_info() to perform that update. 
>> Additionally, if we expose the SystemProperty directly (as done for 
>> other properties) then we can do away with the new 
>> PropertyList_update_value() function that has to search for the 
>> property to be updated.
>>
>> Overall this cuts out a chunk of initialization code that may aid with 
>> startup costs; and simplifies the code.
>>
>> There's some additional history in the bug report.
>>
>> Testing:
>>    - tier 1, 2, 3
>>    - regression test from JDK-8203329:
>>       - 
>> serviceability/jvmti/GetSystemProperty/JvmtiGetSystemPropertyTest.java
>>
>> Thanks,
>> David