How to find fragmented space in G1 regions

[Thomas Schatzl]

Hi,

On Wed, 2017-02-08 at 21:15 +0530, Amit Balode wrote:
> Thanks Thomas, do you know if there is overhead of those flags? I
> think trace would be expensive but what about others? Will they add
> anything to pause time?

  the bottleneck is 99% writing out the data. The internal per-line
calculation overhead is negligible. However the amount of information
printed may cause I/O issues.

I think since at least G1PrintRegionLivenessInfo is a diagnostic
option, you can turn it completely on and off at runtime.
(In JDK9, everything is completely based on the unified logging, you
can do that as well).

Thanks,
  Thomas