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Date: Sun, 10 Oct 2010 15:07:32 -0400 (EDT)
From: "Knut Anders Hatlen (JIRA)" <jira@apache.org>
To: derby-dev@db.apache.org
Subject: [jira] Commented: (DERBY-4741) Make Derby work reliably in the
 presence of thread interrupts
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    [ https://issues.apache.org/jira/browse/DERBY-4741?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12919646#action_12919646 ] 

Knut Anders Hatlen commented on DERBY-4741:
-------------------------------------------

Thanks Dag. The proposed plan sounds good to me.

As to what to do with the interrupt status after a retry, I'd be happy as long as we always either fail or preserve the interrupt status. I don't have any strong opinions on whether or not we should set the interrupt flag raising the exception. I see that the pre-NIO methods that may be interrupted (wait, sleep, join) will throw an exception and *clear* the interrupt status, whereas the interruptible NIO methods will throw an exception and *set* the interrupt status, so the precedence from the class library is ambiguous. I agree, though, that the user's intent is probably to stop the thread, and then preserving the interrupt status sounds reasonable in order to prevent that the thread just runs to the next blocking call and gets blocked there.

> Make Derby work reliably in the presence of thread interrupts
> -------------------------------------------------------------
>
>                 Key: DERBY-4741
>                 URL: https://issues.apache.org/jira/browse/DERBY-4741
>             Project: Derby
>          Issue Type: Bug
>          Components: Store
>    Affects Versions: 10.2.1.6, 10.2.2.0, 10.3.1.4, 10.3.2.1, 10.3.3.0, 10.4.1.3, 10.4.2.0, 10.5.1.1, 10.5.2.0, 10.5.3.0, 10.6.1.0
>            Reporter: Dag H. Wanvik
>            Assignee: Dag H. Wanvik
>         Attachments: derby-4741-nio-container+log+waits+locks.diff, derby-4741-nio-container+log+waits+locks.stat, derby-4741-nio-container+log+waits.diff, derby-4741-nio-container+log+waits.stat, derby-4741-nio-container+log.diff, derby-4741-nio-container+log.stat, derby-4741-nio-container-2.diff, derby-4741-nio-container-2.log, derby-4741-nio-container-2.stat, derby-4741-nio-container-2b.diff, derby-4741-nio-container-2b.stat, xsbt0.log.gz
>
>
> When not executing on a small device VM, Derby has been using the Java NIO classes java.nio.clannel.* for file io.
> If thread is interrupted while executing blocking IO operations in NIO, the ClosedByInterruptException will get thrown. Unfortunately, Derby isn't current architected to retry and complete such operations (before passing on the interrupt), so the Derby database can be left in an inconsistent state and we therefore have to return a database level error. This means the applications can no longer access the database without a shutdown and reboot including a recovery.
> It would be nice if Derby could somehow detect and finish IO operations underway when thread interrupts happen before passing the exception on to the application. Derby embedded is sometimes embedded in applications that use Thread.interrupt to stop threads.

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