String Deduplication in JEP192

[charlie hunt]

On 03/01/2014 07:45 AM, Kirk Pepperdine wrote:
> On Mar 1, 2014, at 2:42 PM, charlie hunt <charlie.hunt at oracle.com> wrote:
>
>> Hi Kirk,
>>
>> Thanks for the good questions. :-)
>>
>> At the risk of jumping in ahead of the JEP authors and reviewers ...
>>
>>> where did you get the statistics from?
>> 900+ profiles
> Customer apps I presume?
Yep
>> If you or others have a repository of profiles, (if can) please share your observations.
> Sorry but I generally don’t keep customers code. ;-)
Understood
>>> If the weak generational hypothesis holds will you not be spending more time deduping soon to be garbage which potentially would place more load on the GC threads?
>> As mentioned in the JEP, you can manipulate the age at which a String becomes a candidate with -XX:StringDeduplicationAgeThreshold.
> Missed that one.. I guess an obvious threshold would be a promotion to tenured????
A reasonable place to start. ;-)  As you know one's goals, i.e. 
throughput, latency or footprint will drive you to the best setting 
assuming a representative workload and monitoring production behavior.
>
> I guess that only partially addresses the cost issues.

Agreed ... no replacement for measurements (on representative data). :-)

charlie
>
> — Kirk
>