RFR [9] 8140687: Move @Contended to the jdk.internal.vm.annotation package (original) (raw)

Chris Hegarty chris.hegarty at oracle.com
Mon Nov 9 13:53:42 UTC 2015

On 09/11/15 12:34, Peter Levart wrote:

On 11/09/2015 01:32 PM, Peter Levart wrote:

On 11/09/2015 11:43 AM, Chris Hegarty wrote: On 02/11/15 10:45, Aleksey Shipilev wrote: On 11/02/2015 02:56 AM, Chris Hegarty wrote: In line with the intended location for other VM annotations, see 8138732 [1], @sun.misc.Contended should be moved to the jdk.internal.vm.annotation package.

http://cr.openjdk.java.net/~chegar/8140687/00/ Changes look good to me. But what's the compatibility story for JSR 166? With this move, we would be unable to bootclasspath JSR 166 JAR, since it references the "old" sun.misc.Contended? Correct. As you are aware, the 166 CVS will fork shortly to support a JDK 9 only version. Artifacts built from the fork are of course not impacted by this change. For existing 166 artifacts, they will not run on JDK 9 as the Contended annotation will not be present. Note that they might actually be able to run. They would just not be @Contended. As I understand, VM just checks the presence of annotations by string value - it doesn't try to materialize them in the form of objects, so it does not fail.

Correct Peter. It does not fail. The annotation is just ignored.

The possible solution would be for VM to support both annotations as aliases for some time.

That is possible, but I don't see this as a such an important issue that it is worth the added complication, given that there will be a JDK 9 specific 166 artifact anyway.

-Chris.

Regards, Peter

-Chris. Thanks, -Aleksey

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