Hi Andy,
thank you for your reply. Good to know. My use case is an RDF exporter
that takes data from a relatively slow data source (like a DBMS). In
order to speed things up, it has multiple threads reading data,
converting it to RDF and then sending generated RDF to their own Jena
Model (one per thread). At the end, they stream the model to a common
sink/stream, such as a file.
Actually I'm designing this with some flexibility: one can chose to pass
a java.util.function.Consumer<Model> to the exporter, that is, an
handler that does something with a thread model, once it is ready.
That's because, I want to reuse the upstream processing for either an
RDF file exporter, or a Neo4J uploader (which should be able to manage
concurrent writings at a finer grain level), or, in general, some other
kind of converter.
That said, I'm OK with making the file writing part synchronized and
hence non really parallel, my question was to understand it better how
Jena works with this.
Best,
Marco.
On 26/11/2017 11:14, Andy Seaborne wrote:
If the output stream is shared, then no. It's buffered internally.
So at small scale, it'll look safe because the whole output is one
buffer or the order was OK. But beyond that, the buffered flushes
will be interleaved and buffer boundaries are based on characters, not
logical unit of the RDF output.
Parallel writing to a shared OutputStream is a bad idea.
What's the use case you have for a shared output stream?
Andy
