RFR: 8219638: ZGC: Free ZNMethodDataOops using GlobalCounter

[Erik Österlund]

Hi,

After discussing this with Per, we found that nowadays we don't even 
need RCU. We can just swap the oop cache under the per nmethod lock, 
which makes the code even simpler.

New webrev:
http://cr.openjdk.java.net/~eosterlund/8219638/webrev.01/

Thanks,
/Erik

On 2019-02-25 13:15, Erik Österlund wrote:
> Hi,
>
> Today, the ZNMethodDataOops use a custom deferred freeing mechanism to 
> handle the case where C1 performs code patching that generates more 
> immediate oops, while the GC is concurrently walking the code cache 
> for class unloading.
> It would be nice to use GlobalCounter instead, which is a more 
> standardized way of doing it.
>
> Webrev:
> http://cr.openjdk.java.net/~eosterlund/8219638/webrev.00/
>
> Bug:
> https://bugs.openjdk.java.net/browse/JDK-8219638
>
> Thanks,
> /Erik