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https://issues.apache.org/jira/browse/JENA-2151?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17402328#comment-17402328
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Andy Seaborne commented on JENA-2151:
-------------------------------------
What kind of iterator is being filtered and where might the {{Iter.filter}}
call be? ARQ makes very limited use of {{Iter.filter}} and all the ones I found
are filtering iterators look safe.
I fear that fixing up one case will not solve your problem. It is not just
filtering; in general, {{Iter}} doesn't close iterators by default.
If it is a {{QueryIterator}} being filtered in TQ code, it would be better to
use or extend one of the {{QueryIter}} such as {{QueryIterProcessBinding}} so
it gets all the machinery. Or if it is being passed out of some code, it might
be better to materialize with filtering so it runs to completion.
There are classes {{IteratorOnClose}} and {{IteratorResourceClosing}} that
added closability on iterators.
> Iter.filter does not close nested iterator
> ------------------------------------------
>
> Key: JENA-2151
> URL: https://issues.apache.org/jira/browse/JENA-2151
> Project: Apache Jena
> Issue Type: Bug
> Affects Versions: Jena 4.1.0
> Reporter: Holger Knublauch
> Priority: Major
> Attachments: IteratorFilter.java
>
>
> 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
> {code:java}
> public static <T> Iterator<T> filter(final Iterator<? extends T> stream,
> final Predicate<T> filter) {
> return new IteratorFilter<T>(stream, filter);
> }
> {code}
> (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).
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