RFR(S): 8166738 - Enable concurrency in Hotspot jtreg testing

[Christian Tornqvist]

Hi everyone,

 

Please review this small change that enables concurrency for the Hotspot
jtreg tests when running them through the make system. Testing done so far
shows very promising speed ups, both when running locally and in JPRT. 

 

It'll automatically calculate a sane concurrency number based on the number
of cores / 2 (with a maximum of 12) and then sets
MaxRAMFraction=concurrency*4 to make sure we don't run out of memory. The
concurrency value can be overridden by setting TEST_JOBS to the desired
concurrency value.

 

On Windows, this change is temporarily commented out since we run into the
intermittent issue described in JDK-8159799. 

 

Webrev:

http://cr.openjdk.java.net/~ctornqvi/webrev/8166738/webrev.00/

 

Bug:

https://bugs.openjdk.java.net/browse/JDK-8166738

 

Thanks,

Christian