RFR(L): 8195097: Make it possible to process StringTable outside safepoint

[Robbin Ehn]

Thanks Ioi!

/Robbin

On 2018-06-05 22:04, Ioi Lam wrote:
> Looks good to me. Thanks
> 
> - Ioi
> 
> 
> On 6/5/18 11:57 AM, coleen.phillimore at oracle.com wrote:
>>
>> This latest version looks good to me also.
>> Coleen
>>
>> On 6/4/18 11:59 AM, Robbin Ehn wrote:
>>> Hi,
>>>
>>> Here is an updated after reviews:
>>> Inc : http://cr.openjdk.java.net/~rehn/8195097/v2/inc/webrev/
>>> Full: http://cr.openjdk.java.net/~rehn/8195097/v2/full/webrev/
>>>
>>> Passed tier 1-3.
>>>
>>> /Robbin
>>>
>>>
>>> On 2018-05-28 15:19, Robbin Ehn wrote:
>>>> Hi all, please review.
>>>>
>>>> This implements the StringTable with the ConcurrentHashtable for managing the
>>>> strings using oopStorage for backing the actual oops via WeakHandles.
>>>>
>>>> The unlinking and freeing of hashtable nodes is moved outside the safepoint,
>>>> which means GC only needs to walk the oopStorage, either concurrently or in a
>>>> safepoint. Walking oopStorage is also faster so there is a good effect on all
>>>> safepoints visiting the oops.
>>>>
>>>> The unlinking and freeing happens during inserts when dead weak oops are
>>>> encountered in that bucket. In any normal workload the stringtable self-cleans
>>>> without needing any additional cleaning. Cleaning/unlinking can also be done
>>>> concurrently via the ServiceThread, it is started when we have a high ‘dead
>>>> factor’. E.g. application have a lot of interned string removes the references
>>>> and never interns again. The ServiceThread also concurrently grows the table if
>>>> ‘load factor’ is high. Both the cleaning and growing take care to not 
>>>> prolonging
>>>> time to safepoint, at the cost of some speed.
>>>>
>>>> Kitchensink24h, multiple tier1-5 with no issue that I can relate to this
>>>> changeset, various benchmark such as JMH, specJBB2015.
>>>>
>>>> Issue: https://bugs.openjdk.java.net/browse/JDK-8195097
>>>> Webrev: http://cr.openjdk.java.net/~rehn/8195097/v0/webrev/
>>>>
>>>> Thanks, Robbin
>>
>