MethodParameters class file format change

David Holmes david.holmes at
Sat Jan 26 12:36:40 UTC 2013

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.


> -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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