[14] RFR 8237396: JvmtiTagMap::weak_oops_do() should not trigger barriers

Stefan Karlsson stefan.karlsson at oracle.com
Mon Jan 20 13:03:14 UTC 2020


Hi Zhengyu,

On 2020-01-17 16:28, Zhengyu Gu wrote:
> Please review this small patch that avoids barriers in 
> JvmtiTagMap::weak_oops_do() method.
> 
> The method is used by GC and GC expects to see raw oops.

For the record, ZGC doesn't require to see raw oops here. The 
unnecessary load barriers will simply pre-clean the oops before the 
closures are applied.

> 
> 
> Bug: https://bugs.openjdk.java.net/browse/JDK-8237396
> Webrev: http://cr.openjdk.java.net/~zgu/JDK-8237396/webrev.00/

Looks good.

I've tested with ZGC as well.

Thanks,
StefanK

> 
> Test:
>    hotspot_gc
>    vmTestbase_nsk_jvmti
>    (fastdebug and release) on x86_64 Linux
> 
>    Submit test in progress.
> 
> Thanks,
> 
> -Zhengyu
> 


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