On 02/05/11 13:22, Mohamed Morsey wrote:
Hi all,
I'm doing a kind of benchmarking on triple stores using DBpedia dataset,
and I'm using Jena-TDB as one of them.
I've installed Joseki server, and configured its config file to use this
dataset.
But when I try to benchmark Jena through Joseki, the performance of
Jena-TDB is very low and too many queries time out.
How do they timeout?
The newest TDB has query timeouts which means when a query does timeout,
it really does stop. Just forgetting about it does not necessarily stop
it executing.
I've assigned 8GB of memory to Joseki.
This will slow the system down.
TDB does not use the heap for DB caches - in 64 bit mode, it uses memory
mapped files. If you use a large heap, there is less RAM for swapped in
memory mapped file space.
I've also tried to query the DBpedia graph directly using
"TDBFactory.createDataset" and "QueryExecutionFactory.create", but when
I iterate through the returned "ResultSet" either with simple loop or
with "ResultSetFormatter.consume", it works only for the first few
queries and afterwards an Exception of type
"com.hp.hpl.jena.tdb.base.block.BlockException" is always thrown.
Stacktrace?
That looks like a bug somewhere, either in the concurrency policy or an
already corrupt database.
Which versions are you using?
Andy
Any help will be appreciated.
