[jira] [Resolved] (JENA-324) An exception thrown from commit() leaves the StoreConnection in an inconsistent state.

["Andy Seaborne (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/JENA-324?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Andy Seaborne resolved JENA-324.
--------------------------------

       Resolution: Fixed
    Fix Version/s: TDB 0.9.4
         Assignee: Andy Seaborne

"fixed" in the sense of "recovery is attempted".  If the hardware is broken, few guarantees can be given.  Partial commits were not possible and still aren't.
                
> An exception thrown from commit() leaves the StoreConnection in an inconsistent state.
> --------------------------------------------------------------------------------------
>
>                 Key: JENA-324
>                 URL: https://issues.apache.org/jira/browse/JENA-324
>             Project: Apache Jena
>          Issue Type: Bug
>          Components: TDB
>    Affects Versions: TDB 0.9.1, TDB 0.9.2, TDB 0.9.3, TDB 0.9.4
>            Reporter: Mark Buquor
>            Assignee: Andy Seaborne
>             Fix For: TDB 0.9.4
>
>
> An exception thrown from commit() leaves the StoreConnection in an inconsistent state.
> Example: After a commit() throws an IOException in prepare() due to insufficient disk space, I see the following behavior:
>     dataset.isInTransaction() == false
>     dataset.abort() throws TDBTransactionException: "Transaction has already committed or aborted"
>     dataset.end() appears OK
>     dataset.begin(ReadWrite.READ) appears OK
>     dataset.begin(ReadWrite.WRITE) blocks on writersWaiting.acquire()
>  
> The debugger shows that the transaction is stuck in limbo: active, closed, and unfinished.
>     TransactionManager.activeWriters: 1
>     TransactionManager.activeTransactions: 1
>         [Transaction: 151 : Mode=WRITE : State=CLOSED : X:\RELM1\]
>             changesPending=true
>             outcome=UNFINISHED
> Short of a fix, it looks like the only option to clear the stuck transaction is StoreConnection.expel(location, true), which has the comment "testing only".
> There's also the indeterminacy of ending a transaction that, as far as I can tell at the Dataset level, may or may not be committed ("Transaction has already committed or aborted").
> Rough outline of a commit:
>     state == TxnState.PREPARING
>     -- commitPrepare()
>     -- journal.write()
>     -- journal.sync() // Commit point.
>     state == TxnState.COMMITED
>     -- noteTxnCommit()
>     -- currentReaderView.set(null)
>     -- writersWaiting.release()
> noteTxnCommit() is called after the commit and performs IO, so it appears that if commit() throws an exception, it's not necessarily true that the transaction is effectively aborted.

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