RFR (S/M): 8169703: G1 crashes with guarantee(pretouch_gang != NULL) failed: No pretouch gang specified

[Thomas Schatzl]

Hi everyone,

  thanks for your reviews.

Webrev incorporating your comments available at
http://cr.openjdk.java.net/~tschatzl/8169703/webrev.0_to_1/
http://cr.openjdk.java.net/~tschatzl/8169703/webrev.1/

One comment inlined further down:

On Fri, 2016-11-18 at 23:31 +0300, Dmitry Fazunenko wrote:
> Hi Thomas,
> 
> A few more comments about the tests:
> 
> 1) would you fix indention to meet "4-space" rule for java.
> 2) TestParallelAlwaysPreTouch.java
> 
> a)
> @run main ...
> -->
> @run main/othervm ...
> 
> b) You start one class, but declare another:
>  * @run main -Xms10M -Xmx100m ... TestAlwaysPreTouch
> public class Test2GbHeap {
> ...
> }
> 
> c) Would it make sense to run a group of existing tests with "-
> XX:+AlwaysPreTouch" regularly (nightly or weekly)

I think the new tests cover all (CDS allocation and mapping, startup
heap expansion, concurrent allocation) but one use case, that is pre-
touch during allocation at the end of GC.

I could try to add a test that particularly tries to test this one, but
that is a bit tricky (to exactly make this allocation that expands the
heap occur at end of gc).

So I do not think anything special is necessary.

Thanks,
  Thomas