RFR: JDK-8148736: Let the G1 heap transition log regions instead of bytes

Bengt Rutisson bengt.rutisson at oracle.com
Tue Feb 2 10:09:56 UTC 2016


Hi Stefan,

Thanks for looking at this!

On 2016-02-02 10:43, Stefan Johansson wrote:
> Hi Bengt,
>
> On 2016-02-01 15:23, Bengt Rutisson wrote:
>>
>> Another update to the webrev:
>> http://cr.openjdk.java.net/~brutisso/8148736/webrev.02/
>>
> Change looks good in general. Just one minor comment about the naming, 
> I think SeparatedUsageInfo and SumSeparatedUsedClosure could be 
> renamed to something like DetailedUsage and DetailedUsageClosure.

Good point.

>
> No need to see a new webrev for those changes.

Here's an updated webrev anyway:

http://cr.openjdk.java.net/~brutisso/8148736/webrev.03/

And here's a diff with the only rename that you suggested:

http://cr.openjdk.java.net/~brutisso/8148736/webrev.02-03.diff/

Thanks,
Bengt

>
> Thanks,
> Stefan
>
>> As discussed in the email thread for "RFR: JDK-8148735: Simplify 
>> G1CollectorPolicy::max_region()​" I will add the 
>> G1CollectorPolicy::max_survivor_regions() method in this change instead.
>>
>> Thanks,
>> Bengt
>>
>> On 2016-02-01 13:48, Bengt Rutisson wrote:
>>>
>>> Hi again,
>>>
>>> I realized that the two macros EXT_SIZE_FORMAT and EXT_SIZE_PARAMS 
>>> are unused. Their usage was removed earlier, but since I am changing 
>>> the code very close by, I thought I can remove them in this change 
>>> as well.
>>>
>>> Here's an updated webrev where these macros are removed as well:
>>> http://cr.openjdk.java.net/~brutisso/8148736/webrev.01/
>>>
>>> Thanks,
>>> Bengt
>>>
>>> On 2016-02-01 11:18, Bengt Rutisson wrote:
>>>>
>>>> Hi everyone,
>>>>
>>>> Could I have a couple of reviews for this change?
>>>>
>>>> http://cr.openjdk.java.net/~brutisso/8148736/webrev.00/
>>>> https://bugs.openjdk.java.net/browse/JDK-8148736
>>>>
>>>> (Note: the webrev is based on top of the change for JDK-8148733, 
>>>> JDK-8148734 and JDK-8148735 that are also currently out for review.)
>>>>
>>>> As described in JDK-8147976 the way G1 now logs the used memory for 
>>>> eden, survivor, old and humongous can be confusing. It does not 
>>>> necessarily add up to the same value as the overall heap usage.
>>>>
>>>> Instead log the number of regions each space is using. This should 
>>>> reduce the confusion. At trace level the exact usage can be logged.
>>>>
>>>> The current logging (running with -Xlog:gc*) looks like this:
>>>>
>>>> [1,395s][info   ][gc,start    ] GC(17) Pause Initial Mark (G1 
>>>> Evacuation Pause) (1,395s)
>>>> [1,417s][info   ][gc,heap     ] GC(17) Eden: 61440K->0K(61440K)
>>>> [1,417s][info   ][gc,heap     ] GC(17) Survivor: 4096K->4096K(8192K)
>>>> [1,417s][info   ][gc,heap     ] GC(17) Old: 61440K->61440K
>>>> [1,417s][info   ][gc,heap     ] GC(17) Humongous: 0K->0K
>>>> [1,417s][info   ][gc,metaspace] GC(17) Metaspace: 
>>>> 2967K->2967K(1056768K)
>>>> [1,417s][info   ][gc          ] GC(17) Pause Initial Mark (G1 
>>>> Evacuation Pause) 123M->63M(128M) (1,395s, 1,417s) 22,030ms
>>>> [1,417s][info   ][gc,cpu      ] GC(17) User=0,15s Sys=0,00s Real=0,02s
>>>>
>>>>
>>>> With the proposed change it will look like this:
>>>>
>>>> [1,391s][info   ][gc,start    ] GC(17) Pause Initial Mark (G1 
>>>> Evacuation Pause) (1,391s)
>>>> [1,407s][info   ][gc,heap     ] GC(17) Eden regions: 59->0(59)
>>>> [1,407s][info   ][gc,heap     ] GC(17) Survivor regions: 5->5(8)
>>>> [1,407s][info   ][gc,heap     ] GC(17) Old regions: 59->59
>>>> [1,407s][info   ][gc,heap     ] GC(17) Humongous regions: 0->0
>>>> [1,407s][info   ][gc,metaspace] GC(17) Metaspace: 
>>>> 2967K->2967K(1056768K)
>>>> [1,408s][info   ][gc          ] GC(17) Pause Initial Mark (G1 
>>>> Evacuation Pause) 121M->63M(128M) (1,391s, 1,408s) 16,632ms
>>>> [1,408s][info   ][gc,cpu      ] GC(17) User=0,15s Sys=0,01s Real=0,02s
>>>>
>>>>
>>>> and if you run with -Xlog:gc*,gc+heap=trace you will get this:
>>>>
>>>> [1,391s][trace  ][gc,heap     ] GC(17) Heap before GC 
>>>> invocations=17 (full 0):
>>>> [1,391s][trace  ][gc,heap     ] GC(17)  garbage-first heap total 
>>>> 131072K, used 124885K [0x00000000f8000000, 0x00000000f8100400, 
>>>> 0x0000000100000000)
>>>> [1,391s][trace  ][gc,heap     ] GC(17)   region size 1024K, 64 
>>>> young (65536K), 5 survivors (5120K)
>>>> [1,391s][trace  ][gc,heap     ] GC(17)  Metaspace used 2967K, 
>>>> capacity 4562K, committed 4864K, reserved 1056768K
>>>> [1,391s][trace  ][gc,heap     ] GC(17)   class space used 277K, 
>>>> capacity 386K, committed 512K, reserved 1048576K
>>>> [1,391s][info   ][gc,start    ] GC(17) Pause Initial Mark (G1 
>>>> Evacuation Pause) (1,391s)
>>>> [1,407s][info   ][gc,heap     ] GC(17) Eden regions: 59->0(59)
>>>> [1,407s][trace  ][gc,heap     ] GC(17)  Used: 0K, Waste: 0K
>>>> [1,407s][info   ][gc,heap     ] GC(17) Survivor regions: 5->5(8)
>>>> [1,407s][trace  ][gc,heap     ] GC(17)  Used: 4385K, Waste: 734K
>>>> [1,407s][info   ][gc,heap     ] GC(17) Old regions: 59->59
>>>> [1,407s][trace  ][gc,heap     ] GC(17)  Used: 60331K, Waste: 85K
>>>> [1,407s][info   ][gc,heap     ] GC(17) Humongous regions: 0->0
>>>> [1,407s][trace  ][gc,heap     ] GC(17)  Used: 0K, Waste: 0K
>>>> [1,407s][info   ][gc,metaspace] GC(17) Metaspace: 
>>>> 2967K->2967K(1056768K)
>>>> [1,407s][trace  ][gc,heap     ] GC(17) Heap after GC invocations=18 
>>>> (full 0):
>>>> [1,408s][trace  ][gc,heap     ] GC(17)  garbage-first heap total 
>>>> 131072K, used 64716K [0x00000000f8000000, 0x00000000f8100400, 
>>>> 0x0000000100000000)
>>>> [1,408s][trace  ][gc,heap     ] GC(17)   region size 1024K, 5 young 
>>>> (5120K), 5 survivors (5120K)
>>>> [1,408s][trace  ][gc,heap     ] GC(17)  Metaspace used 2967K, 
>>>> capacity 4562K, committed 4864K, reserved 1056768K
>>>> [1,408s][trace  ][gc,heap     ] GC(17)   class space used 277K, 
>>>> capacity 386K, committed 512K, reserved 1048576K
>>>> [1,408s][info   ][gc          ] GC(17) Pause Initial Mark (G1 
>>>> Evacuation Pause) 121M->63M(128M) (1,391s, 1,408s) 16,632ms
>>>> [1,408s][info   ][gc,cpu      ] GC(17) User=0,15s Sys=0,01s Real=0,02s
>>>>
>>>>
>>>> Thanks,
>>>> Bengt
>>>
>>
>



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