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

[Robbin Ehn]

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