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List:       openjdk-hotspot-runtime-dev
Subject:    Re: 8162795: RFR: [REDO] MemberNameTable doesn't purge stale entries
From:       Kevin Walls <kevin.walls () oracle ! com>
Date:       2017-02-21 16:26:35
Message-ID: 0aec4d86-aeb3-b21e-2938-0764df41dc5f () oracle ! com
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Hi Coleen,

Actually no, the "REDO" title is from 8162797.

8166852 I was going to close it as a dup of 8162797, hope that's OK.

Thanks
Kevin


On 21/02/2017 15:06, coleen.phillimore@oracle.com wrote:
>
> Hi Kevin, you are checking this in under this bug-id right?
>
> https://bugs.openjdk.java.net/browse/JDK-8166852
>
> thanks,
> Coleen
>
> On 2/21/17 5:11 AM, Kevin Walls wrote:
>> Thanks Coleen!
>>
>>
>> On 20/02/2017 22:04, coleen.phillimore@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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