RFR(XS): 8198510: Limit GC threads for small Java heap

[Thomas Schatzl]

Hi,

On Wed, 2018-02-21 at 16:17 +0000, Doerr, Martin wrote:
> Hi Thomas,
> 
> thanks for discussing this topic with your colleagues.
> 
> I have a webrev which simply switches on UseDynamicNumberOfGCThreads
> by default:
> http://cr.openjdk.java.net/~mdoerr/8198510_gc_threads/webrev.01/
> 
> I'll test it in our nightly tests. If I get approval from 2 reviewers
> and no objections, I'll push it to the submission forest and later to
> jdk/hs.

  - the description of the flag mentions Parallel GC explicitly - this
functionality is available in all (parallel) collectors.

Something like:

"Dynamically choose the number of threads up to a maximum of
ParallelGCThreads parallel collectors will use for garbage collection
work"

  - I just started a run in our test system with that change. Let's see
 if and what fails due to that.

  - unfortunately this is a public interface change, so we need to wait
for the CSR to be approved I filed for you, JDK-8198547.

I filled in all parts except for the specification - it would be nice
to be able to put the inline diff there (since it's so small) and link
the final webrev and a comment containing a reference to this the mail
thread.

I will add (an internal) link to test results when it finishes
hopefully without any new issues.

When all this is done, we need at least one Reviewer (me and maybe
somebody else) to review the CSR and add themselves to the "Reviewed-
by" field (Use the "Edit" button on the top left) so that we can fast-
track it, ie. set it to "Finalized" and then wait for comment from the
CSR approval board :)

Thanks,
  Thomas