[
https://issues.apache.org/jira/browse/JENA-178?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13176151#comment-13176151
]
Andy Seaborne commented on JENA-178:
------------------------------------
I changed all Stacks<> in ARQ to Deque<>. This was a Java6 change due that I'd
not got round to doing.
This changed XML from about 7000 to 5000 (not completely sound test though -
the machine was long running TDB tests at the time so the absolute number isn't
meaningful).
The test program Jena178 does not allow for JITting. Attached is
Jena178_ResultSetSpeed. It makes more difference to the first-run tests
presumably because low-level code is being worked out and it benefits later
code.
The JSON looks slow and IndentedWriter is a common component. It does do
per-character poking. Making it final did not help. Checking for newlines in
printed strings makes some difference.
BufferingWriter looks suspicious even after the encoder improvements after
looking with visualvm. It should buffer in string-space, not in byte-space.
We could swap to StAX. Any reason why not?
Current figures:
https://svn.apache.org/repos/asf/incubator/jena/Scratch/AFS/Jena-Dev/trunk/src/dev/Jena178_ResultSetSpeed.java
-- checking for newlines inside strings
XMLSAX out took: 273
XMLStax out took: 272
XML out took: 1940
XML in took: 397
TSV out took: 128
TSV in took: 330
JSON out took: 1782
JSON in took: 746
-- not checking for newlines inside strings.
XMLSAX out took: 326
XMLStax out took: 274
XML out took: 840
XML in took: 452
TSV out took: 130
TSV in took: 306
JSON out took: 908
JSON in took: 761
JVM:
OpenJDK Runtime Environment (IcedTea6 1.11pre) (6b23~pre11-0ubuntu1.11.10)
OpenJDK 64-Bit Server VM (build 20.0-b11, mixed mode)
> SPARQL Results serialization is slow for some formats with large result sets
> ----------------------------------------------------------------------------
>
> Key: JENA-178
> URL: https://issues.apache.org/jira/browse/JENA-178
> Project: Jena
> Issue Type: Bug
> Components: ARQ
> Affects Versions: ARQ 2.9.0
> Environment: Windows 7 Enterprise 64 bit
> Reporter: Rob Vesse
> Assignee: Damian Steer
> Fix For: ARQ 2.9.1
>
> Attachments: Jena178.java, Jena178.patch,
> TestArqSerializerPerformance.java, XMLOutputSAX.java, XMLOutputStAX.java
>
>
> The SPARQL XML and JSON Result formats are very slow when the result set is
> large. This is surprising to me since both formats are relatively simple and
> should lend themselves to fairly fast streaming serialization and parsing.
> The following are observed performance figures comparing SPARQL XML, SPARQL
> JSON and SPARQL TSV results format. This is the averaged time over 5 runs to
> retrieve the first 50,000 triples from the dataset with a simple SELECT *
> WHERE { ?s ?p ?o } LIMIT 50000 via a HTTP request to Fuseki and iterate over
> the results on the client.
> SPARQL XML = 15.25 seconds
> SPARQL JSON = 10.9 seconds
> SPARQL TSV = 0.54 seconds
> Now obviously TSV is way simpler to serialize and parse than XML/JSON but
> these serializers and parsers should not be 20-30 times slower IMO
> Also for comparison note that doing an equivalent CONSTRUCT { ?s ?p ?p }
> WHERE { ?s ?p ?o } LIMIT 50000 takes only about 2s and that is using RDF/XML
> serialization which I would have expected to be slower because RDF/XML is
> more complex to generate than either SPARQL XML/JSON results. I haven't
> dived into the code in detail to investigate why this is slow yet but do the
> Jena team have any thoughts on this?
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators:
https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira
