RFR(S): 8166461: Deprecate UseAutoGCSelectPolicy

[sangheon]

Hi all,

On 10/07/2016 03:30 PM, Kim Barrett wrote:
>> On Oct 7, 2016, at 4:48 PM, sangheon<sangheon.kim at oracle.com>  wrote:
>>
>> Hi all,
>>
>> Can I have some reviews for this change to deprecate UseAutoGCSelectPolicy command-line option?
>>
>> The intent of UseAutoGCSelectPolicy option is to provide a way to automatically select GC based on target pause time. This option is introduced with AutoGCSelectPauseMillis and if MaxGCPauseMillis is smaller than or equal to AutoGCSelectPauseMillis(and if GC is not specified), low pause collector will be selected. I think it is enough to accomplish auto-GC-selection without UseAutoGCSelectPolicy.
>>
>> This patch only includes adding the deprecation message for UseAutoGCSelectPolicy option.
>>
>> CR:https://bugs.openjdk.java.net/browse/JDK-8166461
>> Webrev:http://cr.openjdk.java.net/~sangheki/8166461/webrev.0
>> Testing: JPRT
>>
>> Thanks,
>> Sangheon
> I thought the plan was to both deprecate the option, and to revert
> its behavior to selecting between a throughput collector (Parallel)
> and a low pause collector (probably CMS as before, though an argument
> could be made for G1).  My understanding of the internal discussion
> was that the deprecation of the option was sufficient to address the
> concern of ergonomically selecting CMS if it is deprecated.
I had an internal discussion including Kim. And we decided to follow 
Kim's suggestion.

This new webrev includes:
1) Reverted the code to select CMS or Parallel GC if 
UseAutoGCSelectPolicy(same behavior as previous version). If not, G1 
will be selected as a default GC.
2) AutoGCSelectPauseMillis will be deprecated together but will be 
addressed by JDK-8167494.

Webrev:
- http://cr.openjdk.java.net/~sangheki/8166461/webrev.1/
- http://cr.openjdk.java.net/~sangheki/8166461/webrev.1_to_0/

Test: JPRT

Thanks,
Sangheon