8162795: RFR: [REDO] MemberNameTable doesn't purge stale entries

Kevin Walls kevin.walls at oracle.com
Tue Feb 21 10:11:41 UTC 2017


Thanks Coleen!


On 20/02/2017 22:04, coleen.phillimore at oracle.com wrote:
> This looks good.
> Thanks for diagnosing this for this internal customer.
> Coleen
>
> On 2/20/17 10:24 AM, Kevin Walls wrote:
>> Hi,
>>
>> This is a review request for:
>> [REDO] MemberNameTable doesn't purge stale entries
>> https://bugs.openjdk.java.net/browse/JDK-8162795
>>
>> For certain apps, such as those with heavy use of the JavaScript 
>> engine, the MemberNameTable and its weak references can introduce 
>> considerable GC overhead.  In some cases GC cannot keep up with the 
>> activity and collection times continually increase.  This is a 
>> regression in jdk8 or later, compared to e.g. jdk7.
>>
>> The change in 8152271:
>> https://bugs.openjdk.java.net/browse/JDK-8152271
>> MemberNameTable doesn't purge stale entries
>>
>> ...fixes this, but that was reverted from 9 due to a regression in a 
>> microbenchmark.  While that benchmark is a concern, more serious is 
>> the regression currently out there for certain apps when moving up to 
>> JDK 8 or 9.  Adding back the change in 8152271 fixes this.
>>
>> Re-applying the original change from 8152271 by Coleen still works, 
>> with one copyright date fixup.  A webrev is:
>>
>> http://cr.openjdk.java.net/~kevinw/8162795/webrev.00/
>>
>> Plan is to re-integrate the 8152271 change in 9 (this request), and 
>> backport to 8.  Meanwhile, a better solution for MemberNameTable in 
>> jdk10 is being pursued in 
>> https://bugs.openjdk.java.net/browse/JDK-8174749
>>
>> Thanks
>> Kevin
>>
>>
>



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