MethodParameters class file format change

David Holmes david.holmes at
Sat Jan 26 12:47:14 UTC 2013

On 26/01/2013 10:36 PM, David Holmes wrote:
> Hi Chris,
> On 26/01/2013 6:22 PM, Chris Hegarty wrote:
>> David,
>> As you know, recently we have seen jdk changes coming in from the
>> hotspot integration forests, thus potentially avoiding a flag day. I'm
>> not saying that this is necessarily a good idea, but just wondering if
>> it is now something that we should reconsider, over the hefty process
>> you described below? That said, it would require the said engineer
>> observe the general engineering processes that are required to
>> integrated into both TL and the hotspot forests.
> There was a lengthy discussion on this twelve months ago. At the time
> JSR-292 was flagged as a special case and not intended as a long-term
> case. Until we have the testing resources, gatekeeping and integration
> resources and processes in place, this is not something that can become
> the norm.

To be clear I'm not saying this can't happen. I'm just saying that the 
right people need to ensure that all the necessary pieces are in place, 
and the procedures established before we actually start doing it on a 
regular basis.


> David
> -----
>> -Chris.
>> On 01/26/2013 07:52 AM, David Holmes wrote:
>>> Eric,
>>> These situations are historically known as Flag Days and they require
>>> careful management.
>>> I don't know exactly what has to be done but the way to approach this is
>>> to modify the VM to be prepared to handle both the old format and the
>>> new. Then after it has reached TL/jdk&langtools update jdk/langtools to
>>> start using the new format. Then if needs be once everything is in sync
>>> you can remove the hotspot code that handles the old format. (I assume
>>> that both old and new format are new with regard class version 52?) That
>>> way nothing breaks.
>>> There must already be tests for this new feature else you would be
>>> pushing untested code, so you would break these tests while your changes
>>> sync up.
>>> David
>>> On 26/01/2013 3:53 AM, Eric McCorkle wrote:
>>>> I don't think anyone is using MethodParameters at this point, but I
>>>> want
>>>> to post this just to be sure.
>>>> The latest version of the spec alters the class file format of
>>>> MethodParameters attributes.
>>>> The latest version can be found here:
>>>> I will be committing patches to tl and hsx which update hotspot and the
>>>> langtools tools to reflect this change. However, this will take some
>>>> time to propagate, and may affect anyone using this feature (most
>>>> likely, to write tests).
>>>> Apologies for any inconvenience,
>>>> Eric

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