RFR 8u: Cherry-pick 8140584: nmethod::oops_do_marking_epilogue always runs verification code

[Andrew Haley]

On 23/05/17 13:18, Aleksey Shipilev wrote:

> Shenandoah-8u runs into the serious performance problem with code
> cache scan -- we are wasting several milliseconds per pause -- and
> it seems to be fixed in 8u152:
> https://bugs.openjdk.java.net/browse/JDK-8140584
> 
> I propose we cherry-pick it to our shenandoah-8u repo, while we wait for it to
> arrive from upstream.
> 
> Andrew, any objections?

We have to think about the criteria we use to decide such things.  It
seems to me that this is a very low-risk patch, but on the other hand
the gains are slight.  On the gripping hand, if we allow in many small
such patches we have a significant divergence from upstream.  Each
patch on its own is no big deal, but they all add up.

So, I'm on the horns of a dilemma.  (Ouch!)

Andrew.