RFR(L): JDK-8046936 : JEP 270: Reserved Stack Areas for Critical Sections

[Frederic Parain]

Karen,

Thank you for your review, my answers are in-lined below.

New Webrevs (including some fixes suggested by Paul Sandoz):

http://cr.openjdk.java.net/~fparain/8046936/webrev.01/hotspot/
http://cr.openjdk.java.net/~fparain/8046936/webrev.01/jdk/

On 20/11/2015 19:44, Karen Kinnear wrote:
> Frederic,
>
> Code review for web revs you sent out.
> Code looks good. I am not as familiar with the compiler code.
>
> I realize you need to check in at least a subset of the java.util.concurrent changes for
> the test to work, so maybe I should not have asked Doug about his preference there.
> Sorry.
>
> I am impressed you found a way to make a reproducible test!
>
> Comments/questions:
> 1. src/cpu/sparc/vm/interp_masm_sparc.cpp line 1144 “is” -> “if”

Fixed

> 2. IIRC, due to another bug with windows handling of our guard pages, this
> is disabled for Windows. Would it be worth putting a comment in the
> bug , 8067946, that once this is fixed, the reserved stack logic on windows
> will need testing before enabling?

More than testing, the implementation would have to be completed on
Windows. I've added a comment to JDK-8067946.

> 3. In get_frame_at_stack_banging_point on Linux, BSD and solaris_x86 if
> this is in interpreter code, you explicitly return the Java sender
> of the current frame. I was expecting to see that on Solaris_sparc and Windows
> as well? I do see the assertion in caller that you do have a java frame.

It doesn't make sense to check the current frame (no bytecode has been
executed yet, so risk of partially executed critical section). I did the
change but not for all platforms. This is now fixed for Solaris_SPARC
and Windows too.

> 4. test line 83 “writtent” -> “written”

Fixed

> 5. I like the way you set up the preallocated exception and then set the message - we may
> try that for default methods in future.
>
> 6. I had a memory that you had found a bug in safe_for_sender - did you already check that in?

I've fixed x86 platforms in JDK-8068655.
I've piggybacked the SPARC fix to this webrev (frame_sparc.cpp:635),
I had hoped it would have been silently accepted :-)


> 7. I see the change in trace.xml, and I see an include added to SharedRuntime.cpp,
> but I didn’t see where it was used - did I just miss it?

trace.xml changes define a new event.
This event is created at sharedRuntime.cpp::3006 and it is used
in the next 3 lines.

Thanks,

Fred

-- 
Frederic Parain - Oracle
Grenoble Engineering Center - France
Phone: +33 4 76 18 81 17
Email: Frederic.Parain at oracle.com