JCStress 0.8

[Aleksey Shipilev]

Hi,

JCStress 0.8 is released and available on Maven Central. This is useful for those who use
JCStress as Maven dependency. There are a few other improvements in the pipeline, but this should be 
useful already.

It comes with the following improvements:

  *) Improved VM support, now enables -XX:+StressCCP, when available.
    7902837: jcstress should support -XX:+StressCCP

  *) Split compilation is now supported. Different actors can be compiled with the combination of 
interpreter/C1/C2 to catch the behaviors caused by possibly different choices taken by different 
compilers. Requires JDK 9+, enabled by default if available. Can be explicitly disabled with "-sc 
false".
    7902857: jcstress: Support split compilation modes

  *) GC/JIT coexistence improvements: the hottest code is now in the specially constructed loop; GC 
thread count is dropped to 2 per forked JVM; default heap size per forked JVM dropped to 256M 
(overridable with "-hs ...").
    7902849: jcstress: Improve hot loops inlining
    7902862: jcstress: Block execution of task/run loops until compiled code is available
    7902856: jcstress: Reconcile GC options

  *) Performance improvement: there was a corner case where jcstress treated classes with static 
initializers are the ones requiring explicit re-initialization with constructors. This is not 
necessary, and the field-zeroing shortcut can be used. Patch contributed by Volker Simonis.
    7902812: Fields can still be default initialized if class has only static intializers

  *) UX improvement: forked VMs are now able to capture VM output. This unfortunately gets less sane 
when VM batching is enabled, so no VM batching is removed, and this should also improve test accuracy.
    7902851: jcstress: Provide the ability to capture VM output
    7902848: jcstress: Remove VM batching support

  *) UX improvement: now that VM output is captured, supplying -vv on modern hsdis-enabled JVM would 
print the assembly for hot loops in tests. Requires JDK 9+ to dump only the hot loops
    7902854: jcstress: Print generated code assembly (optionally)

  *) UX improvement: progress line is now denser and without confusing values
    7902858: jcstress: Clean up progress message

  *) Minor improvements from Sonar:
    7902842: jcstress: fix numeric promotions
    7902843: JCStress: Fix simple test issues found by static analysis

Enjoy!

As always, full test bundles are available here:
   https://builds.shipilev.net/jcstress/

-- 
Thanks,
-Aleksey