RFR 8224179: Shenandoah: CTW test failures with traversal GC

[Aleksey Shipilev]

On 5/20/19 2:59 AM, Zhengyu Gu wrote:
> The failures were due to nested
> nmethod::oops_do_marking_prologue()/nmethod::oops_do_marking_epilogue() calls. This patch is split
> from early JDK-8224115.
> 
> Bug: https://bugs.openjdk.java.net/browse/JDK-8224179
> Webrev: http://cr.openjdk.java.net/~zgu/JDK-8224179/webrev.00/

Looks okay. The synopsis for the change does not reflect what is going on: it should mention what
the change does, i.e. "Introduce all- and cset-specialized ShenandoahRootScanner"?

The patch does lots of code moves. Are those moves necessary to fix the failure? Ideally, the
refactoring and the functional change should go separately. In other words, the fix should make it
absolutely clear what is done, not obscure most of it with reshuffling the code.

-Aleksey