Separate logging for JPMS module/layer

[Ralph Goers]

> On Oct 5, 2018, at 1:10 AM, Luke Hutchison <luke.hutch at gmail.com> wrote:
> 
> On Thu, Oct 4, 2018, 10:27 PM Ralph Goers <rgoers at apache.org <mailto:rgoers at apache.org>> wrote:
> Yes, we have found in some situations using the SecurityManager is faster than StackWalker.
> 
> This is interesting -- how much slower is StackWalker in these situations, and under what condition is there a speed difference? 

Benchmark Mode Cnt Score Error Units StackTraceBenchmark.defaultJava8 thrpt 3 113965.921 ± 119706.986 ops/s StackTraceBenchmark.securityManager thrpt 3 788004.237 ± 82578.567 ops/s StackTraceBenchmark.stackWalker thrpt 3 182902.031 ± 39018.395 ops/s



> 
> Have you seen SecurityManager omit important stack frames, as Mandy suggested might happen? 

No.

> 
> Have you seen situations where the SecurityManager solution doesn't work (due to security permissions), but the StackWalker does work? 

No one has ever complained. However, our code will fall back to other mechanisms if SecurityManager doesn’t work.


Ralph