RFR: 8255973: Add more logging to debug JDK-8255917 [v2]

[Yumin Qi]

On Wed, 11 Nov 2020 10:17:07 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

> Hi, Yumin,
> 
> are you sure UL is safe to use from inside NMT? I see that UL seems to allocate memory, see e.g. LogTagSet::vwrite(). Mentally I had earmarked UL as "don't use in anything at or below os::malloc".
> 
> Other than that, only small nits.
> 
> Cheers, Thomas

The stack allocated buffer size is a const here, logTagSet.cpp:110
const size_t vwrite_buffer_size = 512;
That says if the print string is greater than 512, it will allocate heap for print the part over 512. For this case, it will not be over size of 512.

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PR: https://git.openjdk.java.net/jdk/pull/1150