RFR(L): 8195097: Make it possible to process StringTable outside safepoint
ioi.lam at oracle.com
Tue Jun 5 20:04:08 UTC 2018
Looks good to me. Thanks
On 6/5/18 11:57 AM, coleen.phillimore at oracle.com wrote:
> This latest version looks good to me also.
> On 6/4/18 11:59 AM, Robbin Ehn wrote:
>> 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.
>> 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
>>> 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
>>> encountered in that bucket. In any normal workload the stringtable
>>> 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
>>> 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
>>> 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
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