[JENA-2151] Iter.filter does not close nested iterator

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Jena 4.1.0
• Fix Version/s: Jena 4.2.0
• Assignee: Andy Seaborne
• Reporter: Holger Knublauch
• Created: 19/Aug/21 07:59
• Updated: 14/Oct/21 09:45
• Resolved: 24/Aug/21 09:29

Description

We recently attempted to upgrade our product to Jena 4.1.0 but noticed unclosed iterator warnings. I believe I have tracked it down to the fact that Iter.filter does not return a Closeable iterator and therefore does not close its nested (stream) iterator. I am attaching an implementation class that seems to fix it. With this, org.apache.jena.atlas.iterator.Iter.filter simply need to become

    public static <T> Iterator<T> filter(final Iterator<? extends T> stream, final Predicate<T> filter) {
        return new IteratorFilter<T>(stream, filter);
    }

(Although Iter.filter hasn't changed for a while, I suspect some other changes to Jena caused the SPARQL engine to use it, and this has broken some scenarios for us - in particular calling SPIN/SHACL-SPARQL functions with BGPs in the WHERE clause).

Issue Links

• is related to: JENA-2184 Non-repeatable query with inference model
• links to: GitHub Pull Request #1054