I'm afraid it's you that's done something wrong on this occasion: You are opening both datasets against the same underlying TDB dataset, as part of this open you start a Write transaction which then prevents the second thread from completing because TDB is single writer concurrency.
This is entirely by design, if you want several connections to different datasets on the same thread this should work fine. However your example is trying to make several connections to the same dataset so by definition is going to block. I.e. you must pass in different directories for each thread for your example to work. Also you should be calling .close() on the datasets after you are done with them otherwise you risk corrupting them. You will also want to call either .commit() or .end()/.abort() on the dataset depending on whether you want to commit/rollback your transaction. If you don't call something explicitly before calling .close() it will assume an abort() call and any changes will be list. Rob On 14/10/2013 19:47, "Andreas Grünwald" <[email protected]> wrote: >According to >http://jena.apache.org/documentation/tdb/tdb_transactions.html#multi-threa >ded-use > >only one DataSet connection can be used per Java thread. However, I need >several connections to (different) data models within a single >application. >I noticed that if one tries to use several datasets per single-thread then >the application is blocked when trying to create the second dataset. I >tried to overcome the issue by creating a new thread per dataset (just as >recommended in the Jena documentation). However, the problem is still the >same: The second "TDB.createDataset(..)" statement causes the application >to be blocked. > >This is my (runnable) test code: > >JunitTest: > >public static void main(String[] args) { > String dir >= "/Users/andreas_gruenwald/da-agr/resources/design/jena_tdb/itpm_jena"; > Runnable tdb1 = new TDBThread(dir, null); > Runnable tdb2 = new TDBThread(dir, null); > tdb1.run(); > tdb2.run(); > System.out.println("Finished"); >} > > >TDBThread.java: > >public class TDBThread implements Runnable { > private Dataset tdbDataSet; > private String directory; > >public TDBThread(String directory) { > tdbDataSet = null; > this.directory = directory; >} > >@Override >public void run() { > System.out.println(String.format("Run (directory=%s)...", directory)); > *tdbDataSet** = TDBFactory.createDataset(directory); //blocks here* > System.out.println("Tdbdataset is now " + tdbDataSet); > tdbDataSet.begin(ReadWrite.WRITE); *//causes block* >} >} > >Any ideas what I (or Jena) is doing wrong? > >-- >Andreas Grünwald >Tel.: +43 650 77 82340
