RFR(S): 8160064: StackWalker implementation added logging option without using UL

[Coleen Phillimore]

On 9/27/16 6:54 PM, David Holmes wrote:
> Hi Rachel,
>
> On 28/09/2016 5:47 AM, Rachel Protacio wrote:
>> Hi,
>>
>> Please review this small fix correcting the StackWalker print output
>> mechanism by moving it to Unified Logging. Includes a new jtreg test,
>> and passes JPRT.
>>
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8160064
>> Open webrev: http://cr.openjdk.java.net/~rprotacio/8160064/
>
> Was there a specific reason to make this available in product rather 
> than just "develop" as the existing flag was?
>
>       if (!ShowHiddenFrames && (skip_hidden_frames(mode) || 
> get_caller_class(mode))) {
>         if (method->is_hidden()) {
> !         {
> !           ResourceMark rm;
> !           outputStream* st = Log(stackwalk)::trace_stream();
>
> This should check if logging is enabled before potentially wasting 
> time on the ResourceMark etc. Ditto for other places. Did you revert 
> this due to Coleen's query? 

No, my query was that I was suggesting adding the if 
(log_is_enabled(Trace, stackwalk)) to the code.

> We want to minimise what happens when logging is not enabled - ideally 
> it would be 100% free.

yes.
>
> I also query why all the logging entries are at the trace level?

It seems like this could generate quite a bit of output => trace.

Coleen

> Thanks,
> David
>
>> Thank you!
>> Rachel