RFR(XS): 8134583: sun.management.HotspotCompilation should handle absence of per-thread perf counters

[Claes Redestad]

On 2015-08-27 15:04, Jaroslav Bachorik wrote:
> Hi,
>
> On 27.8.2015 14:41, Claes Redestad wrote:
>> Hi,
>>
>> please review this patch to clean up and make
>> sun.management.HotspotCompilation
>> behave nice if the VM would decide to no longer expose per-compiler
>> thread perf counters:
>>
>> webrev: http://cr.openjdk.java.net/~redestad/jdk9/8134583/webrev.00/
>> bug: https://bugs.openjdk.java.net/browse/JDK-8134583
>
> When already changing this wouldn't it be easier to convert the 
> 'threads' variable to List<CompilerThreadStat> and only add the info 
> for existing compilers threads (eg. not leaving NULL slots in the array).
>
> In 'getCompilerThreadStats' method the 'threads' array is converted to 
> a list anyway.

The CompilerThreadStat object needs to be created on demand (since it 
polls the underlying counters), thus we still need to maintain either an 
array or list of CompilerThreadInfo. Converting CompilerThreadInfo[] to 
a compact (or empty) List<CompilerThreadInfo> may or may not save a few 
bytes, but we'd still have to create a new list every time 
getCompilerThreadStats() is called.

/Claes

>
> -JB-
>
>>
>> /Claes
>