Enis Soztutar commented on HBASE-10656:

Great. Looked at the code for Striped64, it uses Contended annotation though 
which is Java-8 only AFAIK. So we have have to do the same trickery with our 
own padding, thus suffering from the same GC problem above. 

>  high-scale-lib's Counter depends on Oracle (Sun) JRE, and also has some bug
> ----------------------------------------------------------------------------
>                 Key: HBASE-10656
>                 URL: https://issues.apache.org/jira/browse/HBASE-10656
>             Project: HBase
>          Issue Type: Bug
>            Reporter: Hiroshi Ikeda
>            Assignee: Hiroshi Ikeda
>            Priority: Minor
>             Fix For: 0.96.2, 0.98.1, 0.99.0
>         Attachments: 10656-098.v2.txt, 10656-trunk.v2.patch, 10656.096v2.txt, 
> HBASE-10656-0.96.patch, HBASE-10656-addition.patch, HBASE-10656-trunk.patch, 
> MyCounter.java, MyCounter2.java, MyCounter3.java, MyCounterTest.java, 
> MyCounterTest.java, PerformanceTestApp.java, PerformanceTestApp2.java, 
> output.pdf, output.txt, output2.pdf, output2.txt
> Cliff's high-scale-lib's Counter is used in important classes (for example, 
> HRegion) in HBase, but Counter uses sun.misc.Unsafe, that is implementation 
> detail of the Java standard library and belongs to Oracle (Sun). That 
> consequently makes HBase depend on the specific JRE Implementation.
> To make matters worse, Counter has a bug and you may get wrong result if you 
> mix a reading method into your logic calling writing methods.
> In more detail, I think the bug is caused by reading an internal array field 
> without resolving memory caching, which is intentional the comment says, but 
> storing the read result into a volatile field. That field may be not changed 
> after you can see the true values of the array field, and also may be not 
> changed after updating the "next" CAT instance's values in some race 
> condition when extending CAT instance chain.
> Anyway, it is possible that you create a new alternative class which only 
> depends on the standard library. I know Java8 provides its alternative, but 
> HBase should support Java6 and Java7 for some time.

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