RFR: 8232082: Log which shows disabling COOP should be tagged to gc+heap+coops

[David Holmes]

On 10/10/2019 3:26 pm, Yasumasa Suenaga wrote:
> Hi David,
> 
> On 2019/10/10 13:58, David Holmes wrote:
>> Hi Yasumasa,
>>
>> On 10/10/2019 12:34 pm, Yasumasa Suenaga wrote:
>>> Hi all,
>>>
>>> Please review this change:
>>>
>>>    JBS: https://bugs.openjdk.java.net/browse/JDK-8232082
>>>    webrev: http://cr.openjdk.java.net/~ysuenaga/JDK-8232082/webrev.00/
>>>
>>>
>>> Log message is tagged to "cds" when COOP is disabled by ergonomics 
>>> due to heap size. This log has introduced in JDK-8226462.
>>> But it might occur outside of CDS. So it should be tagged to 
>>> "gc+heap+coops" instead of "cds".
>>
>> The logging wasn't put in to show the conditions under which the 
>> ergonomics kicked in, it was put in to show CDS users that it had 
>> kicked in.
> 
> This message would be shown when CDS is disabled as below:
> 
> ```
> $ java -XX:MaxRAM=192g -XX:MaxRAMPercentage=75 -XX:-UseSharedSpaces 
> -Xlog:cds --version
> [0.015s][info][cds] UseCompressedOops and UseCompressedClassPointers 
> have been disabled due to max heap 154618822656 > compressed oop heap 
> 32178700288. Please check the setting of MaxRAMPercentage 75.00.
> openjdk 13 2019-09-17
> OpenJDK Runtime Environment (build 13+33)
> OpenJDK 64-Bit Server VM (build 13+33, mixed mode)
> ```

The Xlog:cds is independent of any use of CDS - part of the logging may 
be to show that CDS is not being used.

> Also this message might be useful for all users.
> Thus I want to change this log tag.

As I said its fine to show it under other circumstances as well but this 
was deemed of interest to people doing CDS logging so it should remain 
enabled in that case.

David
-----

> 
> Thanks,
> 
> Yasumasa
> 
> 
>> So if you think it should be logged under additional conditions, that 
>> is fine, but please do not replace the existing logging.
>>
>> Unfortunately there is no nice way to log the same information under 
>> multiple tags.
>>
>> Thanks,
>> David
>>
>>>
>>>
>>> Thanks,
>>>
>>> Yasumasa