RFR: 8219638: ZGC: Free ZNMethodDataOops using GlobalCounter

Erik Österlund erik.osterlund at oracle.com
Mon Feb 25 14:14:21 UTC 2019


Hi Per,

Thanks for the review.

/Erik

On 2019-02-25 14:35, Per Liden wrote:
> 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
>>



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