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

[coleen.phillimore at oracle.com]

+1
Coleen

On 12/11/19 1:32 PM, Harold Seigel wrote:
> 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
>>
>>