reader/writers, JVMs and threads

[David Jordan <Da...@sas.com>]

The documentation states that TDB can support either multiple readers or a single writer. I am assuming this is respect to JVMs (distinct processes). How are threads handled? Does TDB support multi-threaded applications? If so, can one have multiple threads interacting with TDB, using different Model objects?

David Jordan
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Re: reader/writers, JVMs and threads

[Andy Seaborne <an...@apache.org>]

On 23/09/11 14:00, David Jordan wrote:
> The documentation states that TDB can support either multiple readers
> or a single writer. I am assuming this is respect to JVMs (distinct
> processes). How are threads handled? Does TDB support multi-threaded
> applications? If so, can one have multiple threads interacting with
> TDB, using different Model objects?

Only one JVM can access the database - if you wanted shared access 
between JVMs, then consider running Fuseki, then you will have a shared 
database server.

Within one JVM, either multiple readers or a single writer can be active 
at anyone time per dataset.  There is a lock on the dataset object to help.

Different Models is fine but the rules for MRSW apply.  In TDB, a Model 
is just a view of the dataset - MRSW applies across the whole dataset.

Transactions are currently just being finished up; the released TDB does 
not have transaction support.  TxTDB (will be TDB 0.9 if all goes well) 
is available as a development build.

	Andy