RRF: JEP-271: Unified GC Logging

Bengt Rutisson bengt.rutisson at oracle.com
Wed Nov 25 12:49:31 UTC 2015


Hi Kirk,

On 2015-11-25 08:23, kirk.pepperdine at gmail.com wrote:
>
>> On Nov 24, 2015, at 11:51 AM, Bengt Rutisson 
>> <bengt.rutisson at oracle.com <mailto:bengt.rutisson at oracle.com>> wrote:
>>
>>
>> Hi Kirk,
>>
>> On 2015-11-23 14:26, kirk.pepperdine at gmail.com wrote:
>>> Hi Bengt,
>>>
>>> I’ve not seen anything egregious as of yet though I’m no where near 
>>> done.
>>
>> Thanks for looking at this change!
>>
>>> One comment for ostream.cpp.
>>>
>>> -// log_name comes from -XX:LogFile=log_name, -Xloggc:log_name or
>>> +// log_name comes from -XX:LogFile=log_name or
>>>   // -XX:DumpLoadedClassList=<file_name>
>>>
>>>
>>> IME, -Xloggc:log_name is the most common form used. Not stuck to it, 
>>> just saying…
>>
>> Are you saying that it is scary to remove -Xloggc? Yes, I would 
>> agree. We've discussed it a bit here. It would be nice to get rid of 
>> it since it comes with a bunch of other issues such as log rotation 
>> etc. One way to handle the transition would be to map 
>> -Xloggc=filename to -Xlog:gc*:filename. It wouldn't be 100% correct 
>> and it wouldn't handle the log rotations flags. But maybe it would be 
>> a smoother transition for some users.
>
> It’s a small change and a very sensible one. The only thing I’m 
> suggesting is that it’s worth considering this or any change in light 
> of the complexity/change tax that projects will have to pay to move to 
> 9. I see two arguments here, depreciate in 9, remove in 10. Or, just 
> pile it onto the tax. I guess you could argue that since GC logging 
> flags are already changing, the later solution works best in both the 
> short and long term.

Agreed. I'll look into adding some compatibility mapping for -Xloggc. 
That and the compatibility mappings for PrintGC and PringGCDetails will 
be pushed as a separate change after the main change. This is to make 
sure that we clean out all usages of the old flags from all tests and 
test harnesses that we have by really removing the flags for a while.

Regards,
Bengt

>
> Regards,
> Kirk

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