[OAK-1959] AsyncIndexUpdate unable to cope with missing checkpoint ref

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.0, 1.0.1
• Fix Version/s: 1.0.2, 1.1.0
• Component/s: core
• Assignee: Alex Deparvu
• Reporter: Alex Deparvu
• Created: 09/Jul/14 10:01
• Updated: 01/Oct/14 13:11
• Resolved: 09/Jul/14 10:28

Description

The async index uses a checkpoint reference stored under the :async hidden node as a base for running the index diff.
It might happen that this reference is stale (pointing to checkpoints that no longer exist) so the async indexer logs a warning that it will reindex everything and will start its work.
The trouble is with the #mergeWithConcurrencyCheck which does not cope well with this scenario. Even if the ref checkpoint is null, it will throw a concurrent update exception which will be logged as a misleading debug log Concurrent update detected in the async index update.

Overall the code looks stuck in an endless reindexing loop.

*WARN* [pool-9-thread-1] org.apache.jackrabbit.oak.plugins.index.AsyncIndexUpdate Failed to retrieve previously indexed checkpoint 569d8847-ebb6-4832-a55f-2b0b1a32ae71; re-running the initial async index update
*DEBUG* [pool-9-thread-1] org.apache.jackrabbit.oak.plugins.index.AsyncIndexUpdate Concurrent update detected in the async index update