ClassValue perf?

[Michael Haupt]

Hi Peter,

thank you. I've run the full benchmark in my setup and uploaded the updated cumulative results to http://cr.openjdk.java.net/~mhaupt/8031043/.

The benchmark indeed shows that this latest addition to the group slows down random and sequential access, especially for small numbers of values and classes. The OpenJDK tests are fine; I'm running a batch of internal tests as well.

Given that one concern with this issue, next to reducing footprint, was to optimise for the single-value case, I'm still a bit hesitant even though the sheer amount of code reduction is impressive. I'll evaluate further.

Best,

Michael

> Am 05.05.2016 um 17:21 schrieb Peter Levart <peter.levart at gmail.com>:
> 
> Hi Michael,
> 
> 
> On 05/04/2016 06:02 PM, Michael Haupt wrote:
>> Hi Peter,
>> 
>> thank you for chiming in again! :-) I'll look at this in depth on Friday.
> 
> Good. Because I found bugs in expunging logic and a discrepancy of behavior when a value is installed concurrently by some other thread and then later removed while the 1st thread is still calculating the value. Current ClassValue re-tries the computation until it can make sure there were no concurrent changes to the entry during its computation. I fixed both things and verified that the behavior is now the same:
> 
>     http://cr.openjdk.java.net/~plevart/misc/ClassValue.Alternative2/webrev.02/ <http://cr.openjdk.java.net/~plevart/misc/ClassValue.Alternative2/webrev.02/>
> 
> Regards, Peter


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