ClassValue perf?

[Christian Thalinger]

> On May 6, 2016, at 4:48 AM, Michael Haupt <michael.haupt at oracle.com> wrote:
> 
> 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/ <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.

The main motivation to optimize for the single-value use case is Graal but it’s not super important.  Graal solved this issue in a different way and it’s questionable Graal would go back using ClassValue so don’t worry too much about it.

> 
> Best,
> 
> Michael
> 
>> Am 05.05.2016 um 17:21 schrieb Peter Levart <peter.levart at gmail.com <mailto: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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