[JENA-1785] A newly created node can remain invisible after commit

• Type: Bug
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: Jena 3.13.0, Jena 3.13.1
• Fix Version/s: Jena 3.14.0
• Component/s: TDB2
• Assignee: Andy Seaborne
• Reporter: Pavel Mikhailovskii
• Created: 27/Nov/19 12:42
• Updated: 19/Jan/20 18:18
• Resolved: 10/Dec/19 11:06

Description

A node once marked as non-present (NodeTableCache.nonPresent) can remain invisible even after it's created and the transaction is committed. That might happen because there's no guarantee that all newly created nodes will be eventually added to the "base" version ThreadBufferingCache.baseCache of the node2id_Cache (as the localCache has limited capacity) or removed from the "base" version of the nonPresent cache (even if they were, there would still be a chance of re-adding them by some read transaction).

The simplest fix is to get rid of the nonPresent cache which seems to be of limited use anyway. A more sophisticated fix would involve keeping track of all newly allocated nodes and their removal from the base version of nonPresent cache on transaction commit.

To reproduce: see the attached test.

Issue Links

• causes: JENA-1817 Queued writer transactions cause exception in ThreadBufferingCache
• links to: GitHub Pull Request #646