RFR: JDK-8175312: SA: clhsdb: Provide an improved heap summary for 'universe' for G1GC

Jini George jini.george at oracle.com
Wed Feb 28 07:26:00 UTC 2018

Thank you very much, Stefan. My answers inline.

On 2/27/2018 3:30 PM, Stefan Johansson wrote:
> Hi Jini,

>>> JIRA ID:https://bugs.openjdk.java.net/browse/JDK-8175312
>>> Webrev: http://cr.openjdk.java.net/~jgeorge/8175312/webrev.00/index.html
> It looks like a file is missing, did you forget to add it to the changeset?

Indeed, I had missed that! I added the missing file in the following 


> ---
> open/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/gc/g1/G1CollectedHeap.java:36: 
> error: cannot find symbol
> import sun.jvm.hotspot.gc.shared.PrintRegionClosure;
> ---
> Otherwise the change looks good, but I would like to see the output 
> live. For a big heap this will print a lot of data, just wondering if 
> the universe command is the correct choice for this kind of output. I 
> like having the possibility to print all regions, so I want the change 
> but maybe it should be a different command and 'universe' just prints a 
> little more than before. Something like our logging heap-summary at 
> shutdown:
> garbage-first heap   total 16384K, used 3072K [0x00000000ff000000, 
> 0x0000000100000000)
>   region size 1024K, 4 young (4096K), 0 survivors (0K)
> Metaspace       used 6731K, capacity 6825K, committed 7040K, reserved 
> 1056768K
>   class space    used 559K, capacity 594K, committed 640K, reserved 
> 1048576K

Ok, will add this, and could probably have the region details displayed 
under a new command called "g1regiondetails", or some such, and send out 
a new webrev.


> Thanks,
> Stefan
>>> Modifications have been made to display the regions like:
>>> ...
>>> Region: 0x00000005c5400000,0x00000005c5600000,0x00000005c5600000:Old
>>> Region: 0x00000005c5600000,0x00000005c5800000,0x00000005c5800000:Old
>>> Region: 0x00000005c5800000,0x00000005c5a00000,0x00000005c5a00000:Old
>>> Region: 0x00000005c5a00000,0x00000005c5c00000,0x00000005c5c00000:Old
>>> Region: 0x00000005c5c00000,0x00000005c5c00000,0x00000005c5e00000:Free
>>> Region: 0x00000005c5e00000,0x00000005c5e00000,0x00000005c6000000:Free
>>> Region: 0x00000005c6000000,0x00000005c6200000,0x00000005c6200000:Old
>>> ...
>>> The jtreg test at this point does not include any testing for the 
>>> display of archived or pinned regions. The testing for this will be 
>>> added once JDK-8174994 is resolved.
>>> The SA tests pass with jprt and Mach5.
>>> Thanks,
>>> Jini.

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