MethodParameters class file format change (original) (raw)

Chris Hegarty chris.hegarty at oracle.com
Sat Jan 26 08:22:17 UTC 2013

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.

-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: http://cr.openjdk.java.net/~abuckley/8misc.pdf 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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