G1 GC heap size is not bounded ?

[yao]

Hi Ramki,

JDK version is  1.7.0_40

-Shengzhe


On Mon, Feb 10, 2014 at 1:36 PM, Srinivas Ramakrishna <ysr1729 at gmail.com>wrote:

> Hi Shengzhe --
>
> What's the version of JDK where you're running into this issue, and has
> the JVM had any STW full gc's because of mixed gc's not keeping up?
>
> -- ramki
>
>
> On Mon, Feb 10, 2014 at 11:39 AM, yao <yaoshengzhe at gmail.com> wrote:
>
>> Hi All,
>>
>> We've enabled G1 GC on our cluster for about 1 month and recently we
>> observed the heap size keeps growing (via RES column in top), though very
>> slowly. My question is, is there a way to bound heap size for G1 GC ?
>>
>> We set heap size to 82G
>>
>>
>> *-Xms83868m -Xmx83868m -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC *
>> We found RES column is about 100G, (a few days ago it was about 93G)
>>
>> *$ top*
>> PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
>> 5757 hbase     20   0  104g *100g* 5240 S 271.3 79.6 177771:41 java
>>
>> From previous discussion, Thomas Schatzl pointed out this might be due to
>> large RSet. From below lines in gc log, we found RSet size is about 10.5G.
>> So we get Xmx + RSet = 82G + 10.5G = 92.5G, here you can see there are
>> still unexplained 7.5G data occupied our off-heap.
>>
>> RSet log:
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> * Concurrent RS processed -1601420092 cards  Of 651507426 completed
>> buffers:     634241940 ( 97.3%) by conc RS threads.     17265486 (  2.7%)
>> by mutator threads.  Conc RS threads times(s)           0.00     0.00
>> 0.00     0.00     0.00     0.00     0.00     0.00     0.00     0.00
>> 0.00     0.00     0.00     0.00     0.00     0.00     0.00     0.00
>> \ 0.00     0.00     0.00     0.00     0.00     0.00   Total heap region rem
>> set sizes = 10980692K.  Max = 16182K.  Static structures = 563K, free_lists
>> = 78882K.    197990656 occupied cards represented.    Max size region =
>> 165:(O)[0x00007f0ce0000000,0x00007f0ce2000000,0x00007f0ce2000000], size =
>> 16183K, occupied = 3474K.     Did 0 coarsenings.*
>>
>> Thanks
>> -Shengzhe
>>
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>>
>
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