RFR: JDK-8256367: [windows] Better logging for some system calls

[Yasumasa Suenaga]

On Mon, 16 Nov 2020 07:14:02 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

>>> > LGTM. Should the assert in os::split_reserved_memory() be changed to guarantee so it will stop the product build VM?
>>> 
>>> Thanks Ioi. I'd rather not make it a guarantee - I find those a bad way to communicate errors to the end user. Ideally, the calling function should decide if it is worth continuing, but that would involve fixing ReservedSpace.(first|last)_part and was out of scope for that little fix.
>> 
>> Sounds OK to me. Hopefully we can remove split_reserved_memory soon to make this a non issue.
>
> Hi Yasumasa,
> 
>> Looks good,
> 
> thanks!
> 
>> but should all `log_info()` should be replaced to `log_warning()`? I wonder why the failure would be reported as info level originally.
> 
> No, log_warning() logs unconditionally. I do not want to write to stdout/err unless it is really important, since that output may screw up any parsing tools. In this case, the failures may not be fatal or even be expected. log_info() is a good choice here since it pops up when you activate logging, but at the highest level.
> 
> Cheers, Thomas

Thanks @tstuefe ! I agree with that.

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PR: https://git.openjdk.java.net/jdk/pull/1214