[#SES-674] Unreleased locks when startTransaction() call fails; potential deadlock

Issue Details [XML]

Key:	SES-674
Type:	Bug
Status:	Resolved
Resolution:	Fixed
Priority:	Major
Assignee:	Arjohn Kampman
Reporter:	Brian J. Peterson
Votes:	0
Watchers:	0

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Unreleased locks when startTransaction() call fails; potential deadlock

Created: 26/Jun/09 04:23 PM Updated: 19/Oct/09 12:16 PM

Component/s:

RDBMS Sail, Memory Sail, Native Sail

Affects Version/s:

2.2.4

Fix Version/s:

2.3.0

Environment:

Windows XP SP2

Description

SailConnectionBase.autoStartTransaction calls startTransactionInternal at line 275. If NativeStoreConnection.startTransactionInternal throws an Error from the call to the triple store to start a transaction (NativeStoreConnection: 329), the thread has a transaction lock from the ExclusiveLockManager, but the SailConnectionBase doesn't get to line 276 to set txnActive=true. This means a rollback will not recognize that it has an active transaction and call rollbackInternal at line 314, which means the thread never releases the ExclusiveLockManager.ExclusiveLock. Any attempt to start a transaction will block at ExclusiveLockManager.getExclusiveLock, line 86, waiting for someone to set lockInUse to false. This never happens because no rollback will clear it's lock.

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Change History

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[ Permlink ]

Comment by Arjohn Kampman [30/Jun/09 03:15 PM]

The NativeStore (and MemoryStore too) should release the lock if they fail to start the transaction properly.

[ Permlink ]

Comment by Arjohn Kampman [19/Oct/09 12:16 PM]

Lock that are acquired in startTransactionInternal are now released in case an exception is thrown. This has been fixed in the NativeStore, MemoryStore and RdbmsStore.