RFR(S) 8235629 Remove unnecessary calls to Thread::current

[Harold Seigel]

Looks good!

Thanks, Harold

On 12/11/2019 1:19 PM, Ioi Lam wrote:
> https://bugs.openjdk.java.net/browse/JDK-8235629
> http://cr.openjdk.java.net/~iklam/jdk14/8235629-remove-thread-current.v01/ 
>
>
> + In mutex.cpp, put "assert_owner(Thread::current())" into DEBUG_ONLY 
> to avoid
>   the evaluation of the call in product builds.
> + Changed various "ResourceMark rm;" to "rm(THREAD)".
> + In UL logs, use "ResourceMark rm" only conditionally.
>
> I found these locations by running "java -version" in gdb, setting a 
> breakpoint
> at Thread::current() and logging all the callstacks. So these are by 
> no means complete,
> but are rather an easy-to-fix part of JVM start-up.
>
> Before: 0.0420053188 sec
> After:  0.0417649239 sec
>         99.42770374% = about .6% improvement
>
> Thanks
> - Ioi
>
>