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From "Rick Hillegas (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-4741) Make embedded Derby work reliably in the presence of thread interrupts
Date Tue, 08 Feb 2011 20:29:57 GMT

    [ https://issues.apache.org/jira/browse/DERBY-4741?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12992159#comment-12992159

Rick Hillegas commented on DERBY-4741:

Hi Dag,

Thanks for the functional spec. I am trying to wrap my mind around what application writers
can expect. Is the following a fair summary?

1) If the Thread is interrupted while running outside Derby (that is, not inside a JDBC call),
then Derby does not field the interrupt. The Connection remains alive and Thread.isInterrupted()
will not be touched by Derby.

2) On the other hand, if the Thread is interrupted while running inside a Derby JDBC call...

a) The Connection may be killed and have to be restarted. If the Connection is killed, then
Thread.isInterrupted() will be true. 

b) Alternatively, it is also possible that the interrupt will not kill the Connection. In
this case, the state of Thread.isInterrupted() is unclear to me. I am having a hard time reconciling
"will be still be set...when exiting from the Derby API method" with "it is not deterministic
whether the flag will remain set or be cleared on return".


> Make embedded 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:,,,,,,,,,,
>            Reporter: Dag H. Wanvik
>            Assignee: Dag H. Wanvik
>         Attachments: InterruptResilienceTest.java, MicroAPITest.java, derby-4741-a-01-api-interruptstatus.diff,
derby-4741-a-01-api-interruptstatus.stat, derby-4741-a-02-api-interruptstatus.diff, derby-4741-a-02-api-interruptstatus.stat,
derby-4741-a-03-api-interruptstatus.diff, derby-4741-a-03-api-interruptstatus.stat, derby-4741-a-04-api-interruptstatus.diff,
derby-4741-a-04-api-interruptstatus.stat, derby-4741-all+lenient+resurrect.diff, derby-4741-all+lenient+resurrect.stat,
derby-4741-b-01-nio.diff, derby-4741-b-01-nio.stat, derby-4741-b-02-nio.diff, derby-4741-b-02-nio.stat,
derby-4741-b-03-nio.diff, derby-4741-b-03-nio.stat, derby-4741-b-04-nio.diff, derby-4741-b-04-nio.stat,
derby-4741-c-01-nio.diff, derby-4741-c-01-nio.stat, derby-4741-kristians-01.diff, derby-4741-nio-container+log+waits+locks+throws.diff,
derby-4741-nio-container+log+waits+locks+throws.stat, derby-4741-nio-container+log+waits+locks-2.diff,
derby-4741-nio-container+log+waits+locks-2.stat, 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, derby-4741-raf-stresstest-1.diff, derby-4741-raf-stresstest-1.stat,
derby-4741-raf-stresstest-2.diff, derby-4741-raf-stresstest-2.stat, derby-4741-raf-stresstest-3.diff,
derby-4741-raf-stresstest-3.stat, derby-4741-raf-stresstest-4.diff, derby-4741-raf-stresstest-4.stat,
derby-4741-sleeps-waits-1.diff, derby-4741-sleeps-waits-1.stat, derby-4741-sleeps-waits-2.diff,
derby-4741-sleeps-waits-2.stat, derby-4741-sleeps-waits-3.diff, derby-4741-sleeps-waits-3.stat,
derby-4741-testBatchInterrupt-b.diff, derby-4741-testBatchInterrupt.diff, derby-4741-testQueryInterrupt.diff,
derby-4741-testQueryInterrupt.stat, derby.log, derby.log, interrupts-fs.html, interrupts-fs.html,
> When not executing on a small device VM, Derby has been using the Java NIO classes java.nio.clannel.*
for file io for extra concurrency.
> If a 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 store can be left in an
inconsistent state, although no data is corrupted, and we therefore have to return a database
level error to perform shutdown and recovery. This means the applications can no longer access
the database while a shutdown and reboot including a recovery is taking place.
> 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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