RFR 8153123 : Streamline StackWalker code

[Coleen Phillimore]

Also meant to include core-libs-dev in the email.
Thanks,
Coleen

On 4/5/16 1:27 PM, Coleen Phillimore wrote:
>
> Hi, I've reviewed the hotspot changes and some of the jdk changes. 
> This looks really good.
>
> One comment about the jvm function names:
>
> I think FillInStackTraceElement is too close of a name to 
> Throwable::fill_in_stack_trace().
>
> -JVM_ENTRY(void, JVM_SetMethodInfo(JNIEnv *env, jobject frame))
> +JVM_ENTRY(void, JVM_FillInStackTraceElement(JNIEnv *env, jobject 
> frame, jobject stack))
>    JVMWrapper("JVM_SetMethodInfo");
> - Handle stackFrame(THREAD, JNIHandles::resolve(frame));
> - java_lang_StackFrameInfo::fill_methodInfo(stackFrame, THREAD);
> + Handle stack_frame_info(THREAD, JNIHandles::resolve(frame));
> + Handle stack_trace_element(THREAD, JNIHandles::resolve(stack));
> + java_lang_StackFrameInfo::fill_methodInfo(stack_frame_info, 
> stack_trace_element, THREAD); JVM_END
>
>
> And the function is called fill_methodInfo in the javaClasses function.
>
> I think the JVM and the java_lang_StackFrameInfo function names should 
> be closer.
>
> I wonder if the name JVM_ToStackFrameElement() and 
> java_lang_StackFrameInfo::to_stack_frame_element() would be better and 
> then it'd match the Java name.
>
> Thanks!
> Coleen
>
> On 4/4/16 9:29 PM, Mandy Chung wrote:
>>> On Apr 4, 2016, at 4:45 PM, Brent Christian 
>>> <brent.christian at oracle.com> wrote:
>>>
>>> Hi,
>>>
>>> I'd like to check in some footprint and code reduction changes to 
>>> the java.lang.StackWalker implementation.
>>>
>>> Webrev:
>>> http://cr.openjdk.java.net/~bchristi/8153123/webrev.00/
>>> Bug:
>>> https://bugs.openjdk.java.net/browse/JDK-8153123
>>>
>> This looks good to me.
>>
>> One thing to mention is that this patch is a follow-up work from the 
>> investigation on what it takes to enable Throwable to use StackWalker 
>> (JDK-8141239). The current built-in VM backtrace is very compact and 
>> performant.  We have identified and prototypes the performance 
>> improvements if Throwable backtrace is generated using stack walker.  
>> There are some performance gaps that we agree to defer JDK-8141239 to 
>> a future release and improve the footprint performance and GC 
>> throughput concerns when MemberNames are stored in the throwable 
>> backtrace.
>>
>> Mandy
>>
>