RFR (L): JDK-8061308: Remove iCMS

Jon Masamitsu jon.masamitsu at oracle.com
Wed Oct 22 22:35:13 UTC 2014


On 10/22/2014 5:20 AM, Bengt Rutisson wrote:
>
> [...]
>>
>> There are a couple of comments in the
>> concurrentMarkSweepGeneration.* files than
>> mention EdenSpace that you might want to
>> clean up.
>>
>> 5566   // a set of parallel tasks (via the sampling that the [abortable]
>> 5567   // preclean phase did of EdenSpace, plus the [two] tasks of
>> 5568   // scanning the [two] survivor spaces. Further fine-grain
>>
>> 5188       if (chunk_top == 0) {  // no samples were taken
>> 5189         assert(nth_task == 0 && n_tasks == 1, "Can have only 1 
>> EdenSpace ta     sk");
>> 5190         start = space->bottom();
>
> Good catch. I am not sure what I should change to though. I think 
> EdenSpace was, in these two contexts, more a reference to eden than to 
> a space. How about I change both occurrences to just "eden"?

Yes, I think "eden" fits.

Jon

>
> Bengt
>
>>
>> Reviewed.
>>
>>>
>>> JDK changes:
>>> http://cr.openjdk.java.net/~brutisso/8061308/jdk/
>>> (Just a small update to a test library class.)
>>
>> Looks good.
>>
>> Reviewed.
>>
>> Jon
>>>
>>> JBS bug:
>>> https://bugs.openjdk.java.net/browse/JDK-8061308
>>>
>>> The change removes the incremental mode of CMS. This work is part of 
>>> JEP 214 (http://openjdk.java.net/jeps/214). There are quite a few 
>>> lines changed. Mostly it is just removal of code and it should 
>>> hopefully be fairly straight forward to review.
>>>
>>> One interesting side effect of removing iCMS was that the 
>>> ConcEdenSpace (a subclass in the Space hierarchy) could be removed. 
>>> It implemented the "soft-end" feature that only iCMS was taking 
>>> advantage of. When I had removed ConcEdenSpace it turned out that 
>>> its superclass, EdenSpace, was actually an unnecessary class that 
>>> did not add anything so I removed that too. When I then went to 
>>> update the comment in space.hpp that describes the Space hierarchy I 
>>> noticed that the description of the hierarchy was completely 
>>> out-dated. Rather than bringing it up-to-date I removed the comment. 
>>> I think that type of information will only get out-dated quickly 
>>> again and it is much easier to let your IDE create the correct type 
>>> hierarchy view dynamically for you.
>>>
>>> Thanks,
>>> Bengt
>>
>



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