Mark Buquor created JENA-324:
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Summary: 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 0.9.3, TDB 0.9.2, TDB 0.9.1, TDB 0.9.4
Reporter: Mark Buquor
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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