You may need to call XQuery.execute, or call QueryProcessor.register
(and, finally, unregister) before retrieving results; but maybe you
should prepare an MCVE for us?

On Sun, Oct 9, 2016 at 4:20 PM, Erdal Karaca <erdal.karaca.de@gmail.com> wrote:
> Hi Christian,
> I have setup a stress test to access the same DB in parallel. I have only
> one call to the Context constructor and using that same Context instance for
> all executions.
> I still get this exception:
> Caused by: java.nio.channels.OverlappingFileLockException
> at sun.nio.ch.SharedFileLockTable.checkList(FileLockTable.java:255)
> at sun.nio.ch.SharedFileLockTable.add(FileLockTable.java:152)
> at sun.nio.ch.FileChannelImpl.tryLock(FileChannelImpl.java:1108)
> at org.basex.io.random.TableDiskAccess.lock(TableDiskAccess.java:139)
> at org.basex.data.DiskData.startUpdate(DiskData.java:207)
> at org.basex.query.up.ContextModifier.apply(ContextModifier.java:131)
> at org.basex.query.up.Updates.apply(Updates.java:157)
> at org.basex.query.QueryContext.iter(QueryContext.java:351)
> at org.basex.query.QueryProcessor.value(QueryProcessor.java:101)
>
> I am accessing the returned elements (of the queries) via a Value.iter()
> iterator.
> The queries returns a sequence of 100 elements.
>
> Each access to the DB has its own subtree.
> I.e. if "user 1" accesses the DB, then he only accesses the subtree assigned
> to him.
>
> This is the DB tree structure:
> MyDB
> + users/usr1.xml/container
> + users/usr2.xml/container
> + ...
> + users/usrN.xml/container
>
> Are iterators also thread-safe?
> If not, what can I use instead?
>
> (Standalone unit test will follow.)
>
> 2016-10-06 20:07 GMT+02:00 Christian Grün <christian.gruen@gmail.com>:
>>
>> > I mean, once I have the Context object and opened a database, is it safe
>> > to
>> > access (read/write) it from multiple threads?
>>
>> It depends on how you do it ;) If you call Command.execute() with the
>> same Context instance, you should be safe.
>
>