[JENA-1302] Intermittent Lucene prepareCommit exception during heavy read/write load

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Jena 3.3.0
• Fix Version/s: Jena 3.8.0
• Component/s: Fuseki, TDB, Text

Environment

CentOS 7.3 inside VM, 2 cores, OpenJDK 1.8.0_121 (64-bit), 1GB JVM heap, Fuseki running as service

• Assignee: Andy Seaborne
• Reporter: Vilnis Termanis (Iotic Labs)
• Created: 03/Mar/17 16:15
• Updated: 29/Jun/18 10:13
• Resolved: 11/May/18 12:04

Description

(Note: Could not add Fuseki 2.6.0 as affected version although I assume this is a TDB/text rather than Fuseki-related issue.)

Steps:

1. Start with plain Fuseki + given configuration (TDB store + lucene text indexing)
2. Import 1k.ttl
3. Run lockup.py (same host, mix of multiple parallel updates & single select)

Result:
Every now and again one of the update queries fails with a 500 server error which is logged as:
DatasetGraphText ERROR Exception in prepareCommit: prepareCommit was already called with no corresponding call to commit

Notes:

• Not reproducible without fix for JENA-1296 (and discovered during fix verification for said issue)
• Run with apache-jena-fuseki-2.6.0-20170228.233930-10.tar.gz
• From cold-start of Fuseki, occurs within 30s of script run
• Supplied test script required Python 3, rdflib>=4.2.2 & SPARQLWrapper>=1.8.0

Issue Links

• is blocked by: JENA-1542 Allow addition of transaction components after initial setup.
• links to: GitHub Pull Request #225