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From "Dag H. Wanvik (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-4741) Make embedded Derby work reliably in the presence of thread interrupts
Date Wed, 09 Feb 2011 01:33:57 GMT

    [ https://issues.apache.org/jira/browse/DERBY-4741?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12992279#comment-12992279
] 

Dag H. Wanvik commented on DERBY-4741:
--------------------------------------

Thanks for reading the spec, Rick.

1) Not true. If the flag is set at the time the Derby API call, Derby may throw. Derby can't
know exactly when the thread was interrupted, it can only notice it by either a) seeing Java
API methods return exceptions, or b) testing the flag explicitly. We do not test the flag
on Derby API method entry. We heed (i.e. throw) interrupts in the specified situations enumerated
in the spec.

2b) The flag will remain set when exitting from in all cases. The note about deterministic
only applies if the flag *is attemped cleared* by another thread while the Derby API call
is still executing. If we ever saw an interrupt and had to clear it to make execution continue,
e.g. for NIO, we set it again at Derby API method exit, whether we throw or not. This means
that any attempt to clear it while Derby is executing could be lost, depending on exactly
when the clearing attempt was made, hence "non-deterministic".


> 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: 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: 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,
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 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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