RFR(M): 8248401: Refactor/unify RMI gc support functionality
Stefan Karlsson
stefan.karlsson at oracle.com
Fri Aug 7 07:42:24 UTC 2020
On 2020-08-04 12:02, Thomas Schatzl wrote:
> Hi Stefan,
>
> thanks for your review.
>
> On 03.08.20 13:30, Stefan Karlsson wrote:
>> Hi Thomas,
>>
>> Not a complete review, but regarding the ZGC change, I don't think
>> it's appropriate to add a callback to Universe/CollectedHeap to
>> ZStatCycle. Most functions in ZStat only collects and print
>> statistics, and does not trigger external events. I think moving it to
>> the call would be cleaner:
>>
>> ~ZDriverGCScope() {
>> ...
>> // Update statistics
>> ZStatCycle::at_end(_gc_cause, boost_factor);
>>
>> // Update data used by soft reference policy
>> Universe::update_heap_info_at_gc();
>>
>> // Maybe add the call here?
>> ...
>> }
>>
>
> Thank you for pointing out the appropriate place in ZGC. Done.
>
>> Seeing this, it's also apparent that some of the "last_gc" info has
>> historically been recorded in Universe:
>>
>> void Universe::update_heap_info_at_gc() {
>> _heap_capacity_at_last_gc = heap()->capacity();
>> _heap_used_at_last_gc = heap()->used();
>> }
>>
>> while _last_whole_heap_examined_time_ns is recorded in CollectedHeap.
>> I think we should create a RFR to move the heap variables out of
>> Universe.
>
> Done, JDK-8250961.
>
> In addition to above changes, I tried to move the new call closer to
> Universe::update_heap_info_at_gc() in a few places and improve naming of
> some local variables.
>
> New webrevs:
> http://cr.openjdk.java.net/~tschatzl/8248401/webrev.0_to_1 (diff)
> http://cr.openjdk.java.net/~tschatzl/8248401/webrev.1 (full)
ZGC changes look good.
Thanks,
StefanK
>
> Reran the test 300 times with these changes.
>
> Thanks,
> Thomas
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