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From "Knut Anders Hatlen (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DERBY-6891) Investigate concurrency improvements to DerbyObservable and DerbyObserver
Date Thu, 23 Jun 2016 12:58:16 GMT

    [ https://issues.apache.org/jira/browse/DERBY-6891?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15346382#comment-15346382

Knut Anders Hatlen commented on DERBY-6891:

I'm wondering if the synchronization in DerbyObservable is quite right. Most of the methods
synchronize implicitly on the Vector. But the notifyObservers() method synchronizes on "this"
instead, which is the DerbyObservable instance. And setChanged() has no synchronization, even
though it manipulates a flag which notifyObservers() checks inside a synchronized block.

> Investigate concurrency improvements to DerbyObservable and DerbyObserver
> -------------------------------------------------------------------------
>                 Key: DERBY-6891
>                 URL: https://issues.apache.org/jira/browse/DERBY-6891
>             Project: Derby
>          Issue Type: Improvement
>          Components: Store
>            Reporter: Rick Hillegas
> As part of derby-6856, we introduced a pair of classes which manage callbacks between
classes in the Store layer. The classes are DerbyObservable and DerbyObserver. They replace
the deprecated Observer and Observable classes in the JVM and allow Derby to build without
deprecation warnings. Right now, callbacks are managed by a Vector. It is quite likely that
the concurrency of these classes (and therefore of the Store layer) could be boosted by using
some mechanism from java.util.concurrent.

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