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

coleen.phillimore at oracle.com coleen.phillimore at oracle.com
Mon Feb 20 22:04:01 UTC 2017

This looks good.
Thanks for diagnosing this for this internal customer.

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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