Hi Stefan,
This is great - if I want to try it out, what order do the changes
apply, does the 8218746 webrev apply to create ZExternalBitMap.java and
then the 8218922 webrev?
Thanks
Kevin
On 14/02/2019 17:12, Stefan Karlsson wrote:
Hi again,
I've separated the live regions iteration refactoring into this patch:
https://cr.openjdk.java.net/~stefank/8219003/webrev.01/
And use this RFE for the ZGC specific parts:
https://cr.openjdk.java.net/~stefank/8218922/webrev.02/
Thanks,
StefanK
On 2019-02-14 14:39, Stefan Karlsson wrote:
Hi Yasumasa,
On 2019-02-14 14:11, Yasumasa Suenaga wrote:
Hi Stefan,
Maybe this is enough to enable a bit more SA debugging capabilities
when
running with ZGC? What do you think, should we bring in this change?
I think it should be brought this in.
I filed same issue as JDK-8207843, but I've not yet worked.
So I will close it as duplicate of your change.
To be able to implement this more cleanly I've restructured the live
region collection, and pushed GC specific code into the specific GCs.
There are some extra usage of generics to make the code a bit
easier to
read and develop.
IMHO refactoring for live region collection and ZGC related changes
should
be separated. What do you think?
Yes. I think that would be good. I'll separate this out into two
changes.
Your change looks good to me.
BTW, did you check `jhsdb jmap --binaryheap` with this change?
Yes, when testing this I ran all tests in serviceability/sa and
manually tested the command above.
While testing this I also had this patch applied to enable SA hprof
for ZGC:
http://cr.openjdk.java.net/~stefank/8218970/webrev.01/
And used this patch to turn off the ZGC filtering in the tests:
http://cr.openjdk.java.net/~stefank/8218978/webrev.01/
I'm currently rerunning the tests to see that the latest changes
didn't break anything.
Thanks,
StefanK
Thanks,
Yasumasa
On 2019/02/13 23:52, Stefan Karlsson wrote:
Hi all,
Please review / comment on this patch to enable a best-effort live
heap
region iteration implementation in ZGC.
http://cr.openjdk.java.net/~stefank/8218922/webrev.01/
https://bugs.openjdk.java.net/browse/JDK-8218922
The SA has functionally that relies on live heap region information
from
the GCs. This is problematic when dead objects are left in the
heap, and
their classes have been unloaded.
Because of this ZGC has so far not implemented this feature.
However, we
could provide a best-effort implementation that most likely will
work if
classes are not unloaded (or class unloading is turned off), and
otherwise might fail to fully parse and report all live heap regions.
For active, non-relocating pages the patch simply returns [start, top)
and for pages being actively relocated, it reports regions containing
the non-forwarded objects, the other objects are either dead or
could be
found in one of the to-regions.
With this patch I'm able to get heap histograms with ZGC.
Maybe this is enough to enable a bit more SA debugging capabilities
when
running with ZGC? What do you think, should we bring in this change?
To be able to implement this more cleanly I've restructured the live
region collection, and pushed GC specific code into the specific GCs.
There are some extra usage of generics to make the code a bit
easier to
read and develop.
Thanks,
StefanK
