RFR 4947890 : Minimize JNI upcalls in system-properties initialization

[Mandy Chung]

Hi Roger,

Does this change improve the startup performance?  initProperties
is done in initPhase1 where the Java code is running in interpreted
mode.  Brent did the measurement some time ago that JNI calls
is one cost while executing quite a lot of bytecodes in
interpreted mode is another cost.

Mandy

On 11/13/18 7:59 AM, Roger Riggs wrote:
> Please review a re-implementation of the initialization of System 
> properties
> moving some functions from native to Java.
>
> The upcalls from native to java for each property are replaced by a 
> mechanism
> to gather the platform, VM and command line properties and return them
> from a single JNI call.  The creation of the Properties instance and 
> applying
> command line overrides is handled in Java instead of native.
>
> The JVM_initProperties interface in Hotspot is replaced by 
> JVM_getProperties.
>
> Webrev:
>   http://cr.openjdk.java.net/~rriggs/webrev-props-only-raw/
>
> Issue:
>   https://bugs.openjdk.java.net/browse/JDK-4947890
>
> Thanks, Roger
>