[JENA-467] IRIResolverNormal should use synchronized CacheLRU

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Jena 2.10.1
• Fix Version/s: Jena 2.11.0
• Component/s: ARQ

Environment

Any IBM JRE 6 or higher

• Assignee: Andy Seaborne
• Reporter: Simon Helsen
• Created: 05/Jun/13 18:59
• Updated: 26/Nov/13 19:08
• Resolved: 06/Jun/13 15:06

Description

The following exception may occur on an IBM JRE 6 or higher when more than one thread requires access to the org.apache.jena.atlas.lib.cache.CacheLRU embedded in IRIResolverNormal:

Caused by: java.lang.NullPointerException
at java.util.LinkedHashMap.get(LinkedHashMap.java:337)
at org.apache.jena.atlas.lib.cache.CacheLRU.get(CacheLRU.java:53)
at org.apache.jena.riot.system.IRIResolver$IRIResolverNormal.resolveSilent(IRIResolver.java:403)
at org.apache.jena.riot.system.IRIResolver$IRIResolverNormal.<init>(IRIResolver.java:359)
at org.apache.jena.riot.system.IRIResolver.create(IRIResolver.java:212)
at org.apache.jena.riot.system.RiotLib.profile(RiotLib.java:141)
at org.apache.jena.riot.system.RiotLib.profile(RiotLib.java:130)
at org.apache.jena.riot.system.RiotLib.profile(RiotLib.java:117)
at org.apache.jena.riot.RiotReader.createParserTurtle(RiotReader.java:310)
at org.apache.jena.riot.RiotReader.createParser(RiotReader.java:142)
at org.apache.jena.riot.RiotReader.createParser(RiotReader.java:133)
at org.apache.jena.riot.RDFParserRegistry$ReaderRIOTFactoryImpl$1.read(RDFParserRegistry.java:141)
at org.apache.jena.riot.RDFDataMgr.process(RDFDataMgr.java:760)
at org.apache.jena.riot.RDFDataMgr.read(RDFDataMgr.java:258)
at org.apache.jena.riot.RDFDataMgr.read(RDFDataMgr.java:244)
... 20 more

The problem seems to only occurs on IBM JRE 6 or higher as its implementation of LinkedHashMap is not thread safe. Note that the JDK specification does not required LinkedHashMap to be thread safe.

The solution is to make use of CacheFactory.createSync when creating the Cache in the IRIResolverNormal. Patch attached

Issue Links

• is cloned by: JENA-597 IRIResolverNormal needs thread safe CacheLRU