[jira] [Comment Edited] (JENA-1702) InputStream for HTTP constructModel queries are not closed

["A. Soroka (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/JENA-1702?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16816327#comment-16816327 ] 

A. Soroka edited comment on JENA-1702 at 4/12/19 2:53 PM:
----------------------------------------------------------

Hi, [~trueg]! Thanks for the report.

It could be that we're looking in two different code paths, but my tracing of {{RDFConnection.queryConstruct(String)}} leads me (via {{QueryExecution.execConstruct() => QueryEngineHTTP.execConstruct() => QueryEngineHTTP.execConstruct(Model)}} ) to [this|https://github.com/apache/jena/blob/master/jena-arq/src/main/java/org/apache/jena/sparql/engine/http/QueryEngineHTTP.java#L440] method:
{code:java}
    private Model execModel(Model model) {
        Pair<InputStream, Lang> p = execConstructWorker(modelContentType) ;
        try(InputStream in = p.getLeft()) {
            Lang lang = p.getRight() ;
            RDFDataMgr.read(model, in, lang);
        } catch (IOException ex) { IO.exception(ex); }
        finally { this.close(); }
        return model;
}
{code}
in which it seems that the {{InputStream}} is indeed being closed via {{try-with-resource}} at line 440. Can you describe the code path you found in which it is not?

Another question: are you closing the connection between each request (it looks like that from your code)? I think that's not ideal-- I believe you can safely reuse {{RDFConnection}} for a multi-request "conversation".


was (Author: ajs6f):
Hi, [~trueg]! Thanks for the report.

It could be that we're looking in two different code paths, but my tracing of {{RDFConnection.queryConstruct(String)}} leads me (via {{QueryExecution.execConstruct() => QueryEngineHTTP.execConstruct() => QueryEngineHTTP.execConstruct(Model)}}} ) to [this|https://github.com/apache/jena/blob/master/jena-arq/src/main/java/org/apache/jena/sparql/engine/http/QueryEngineHTTP.java#L440] method:
{code:java}
    private Model execModel(Model model) {
        Pair<InputStream, Lang> p = execConstructWorker(modelContentType) ;
        try(InputStream in = p.getLeft()) {
            Lang lang = p.getRight() ;
            RDFDataMgr.read(model, in, lang);
        } catch (IOException ex) { IO.exception(ex); }
        finally { this.close(); }
        return model;
}
{code}

in which it seems that the {{InputStream}} is indeed being closed via {{try-with-resource}} at line 440. Can you describe the code path you found in which it is not?

Another question: are you closing the connection between each request (it looks like that from your code)? I think that's not ideal-- I believe you can safely reuse {{RDFConnection}} for a multi-request "conversation".


> InputStream for HTTP constructModel queries are not closed
> ----------------------------------------------------------
>
>                 Key: JENA-1702
>                 URL: https://issues.apache.org/jira/browse/JENA-1702
>             Project: Apache Jena
>          Issue Type: Bug
>          Components: ARQ
>    Affects Versions: Jena 3.10.0
>            Reporter: Sebastian Trüg
>            Priority: Major
>
> I am accessing a Fuseki installation as follows:
> {code:java}
> String uri = fusekiHost + "/" + dataset;
> RDFConnection conn = RDFConnectionFuseki.create().destination(uri).build();
> try(RDFConnection conn = createConnection(dataModelDs)) {
>   Model model = conn.queryConstruct("construct { ?s ?p ?o . } where { ?s ?p ?o . }");
>   return model;
> }{code}
> The problem is that after 5 of these requests the Spring boot application this code runs in blocks due to the PoolingHttpClientConnectionManager running out of free routes.
> After lots of debugging I noticed that the InputStream that is used to read the data is never closed.
> InputStreams from "select" requests are closed in QueryEngineHTTP::close due to "retainedConnection" being set.
> The same is not true for "construct" queries since their results are parsed via RDFDataMgr which does not close the InputStream.
> I do not understand the code well enough to propose a proper solution but maybe just setting "retainedConnection" for construct queries would be enough? Either way, I think the stream needs to be closed somehow.



--
This message was sent by Atlassian JIRA
(v7.6.3#76005)