RFR 8153123 : Streamline StackWalker code

[Coleen Phillimore]

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
>