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

Bengt Rutisson bengt.rutisson at oracle.com
Mon Feb 1 12:48:24 UTC 2016


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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