[jira] [Updated] (DERBY-4478) Use AtomicLong for XactFactory.tranId

["Knut Anders Hatlen (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/DERBY-4478?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Knut Anders Hatlen updated DERBY-4478:
--------------------------------------

    Attachment: d4478-1a.diff

Now that Java 6 is the minimum level and AtomicLong is available on all supported platforms, I think we should just do this.

The attached patch d4478-1a.diff makes the suggested change.

I repeated the scalability experiment from DERBY-3092. The result was the same as back then: this change on its own didn't seem to affect scalability one way or another.

Still, I think an AtomicLong is the right abstraction for this use, and it makes the code slightly simpler, so I think it's an improvement nevertheless.

All the regression tests ran cleanly with the patch.
                
> Use AtomicLong for XactFactory.tranId
> -------------------------------------
>
>                 Key: DERBY-4478
>                 URL: https://issues.apache.org/jira/browse/DERBY-4478
>             Project: Derby
>          Issue Type: Improvement
>          Components: Store
>    Affects Versions: 10.6.1.0
>            Reporter: Knut Anders Hatlen
>            Assignee: Knut Anders Hatlen
>            Priority: Minor
>         Attachments: d4478-1a.diff
>
>
> Dyre Tjeldvoll posted some results on DERBY-3092 that indicated that some types of load might cause contention on XactFactory.tranId (a shared long), and suggested that it was replaced with a java.util.concurrent.atomic.AtomicLong on the platforms that support java.util.concurrent.*.
> I'm splitting this issue out from DERBY-3092 so that the two possible improvements reported there can be addressed independently.

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