RFR: 8219638: ZGC: Free ZNMethodDataOops using GlobalCounter

[Per Liden]

Looks good!

/Per

On 2/25/19 2:29 PM, Erik Österlund wrote:
> 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
>