RFR(M): 8204613: StringTable: Calculates wrong number of uncleaned items.

Robbin Ehn robbin.ehn at oracle.com
Wed Jun 13 12:31:39 UTC 2018

Thanks Per!


On 06/13/2018 02:20 PM, Per Liden wrote:
> Looks good Robbin!
> /Per
> On 06/13/2018 12:44 PM, Robbin Ehn wrote:
>> Hi, Stefan pointed out that there are some useless methods calls since we 
>> don't remove any strings in some of the walks.
>> Serial, Parallel and CMS only removes strings in serial call to unlink.
>> G1 only removes strings in StringAndSymbolCleaningTask.
>> I reverted does unneeded changes, leaving the patch with only G1 and ZGC 
>> changes (+ stringtable):
>> http://cr.openjdk.java.net/~rehn/8204613/v2/webrev/
>> Thanks Stefan!
>> /Robbin
>> On 06/11/2018 06:09 PM, Robbin Ehn wrote:
>>> Hi all, please review.
>>> The StringTable lazy evicts dead string, until a dead string is evicted it 
>>> will be counted as a dead string. If it is not evicted before next GC cycle 
>>> it is counted again, making the count of uncleaned strings skew.
>>> Also ZGC walks the strings without using the stringtable GC API, but it needs 
>>> to be-able to feedback the number of dead strings to get the cleaning 
>>> functionality.
>>> There is a big probability that ZGC makes it in before this change-set, so I 
>>> included ZGC changes.
>>> There was a compile issue on slowdebug on windows for 
>>> create_archived_string(), I added NOT_CDS_JAVA_HEAP_RETURN_(NULL) for it.
>>> Change-set: http://cr.openjdk.java.net/~rehn/8204613/webrev/index.html
>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8204613
>>> T1-3 with ZGC testing on, no related issues and manual JMH testing.
>>> Thanks, Robbin

More information about the zgc-dev mailing list