Hi there, Sorry, I lost track (but at least I’m back)… Does this also happen with newer versions of BaseX, such as with the latest release or the latest snapshot [1]?
Thanks in advance, Christian [1] http://files.basex.org/releases/latest/ On Wed, Aug 24, 2016 at 3:19 PM, Dirk Kirsten <d...@basex.org> wrote: > Hello Christophe, > > this very much looks like a bug to me. Certainly, we should catch an NPE in > any case. A brief look at the code shows this is during closing, so I guess > it is a concurrency issue. I would guess that the number of instances isn't > even relevant, but instead that you moved to another machine which might > simply behave differently because it is faster or the scheduler might behave > a big differently, etc. pp. > > Answering your specific questions: > > 1) It is legal. We are not going to sue you ;) No, it should (in theory) be > fine > > 2) No, not at the moment. At least i am not aware of it > > 3) Yes, maybe you can try that. As said before, i guess the behaviour change > is caused be the different computer, not the number of instances (but of > course it might also increase the likelihood of a race condition if there > are more parallel instances) > > 4) I don't think so. I guess you will have to wait until Christian is back > from his vacation and tries to fix the bug. > > Cheers > > Dirk > > > On 08/24/2016 03:06 PM, cmarch...@oxiane.com wrote: > > Hello, > > as discussed here few monthes ago, I do this : > Install many instances (8) of BaseX on the same computer > Start one instance, here called "main-instance" > Create a database "library" , and load a filesystem directory into "library" > Stop main-instance > For each "other-instance", create a sym-link to main-instance/data/library > Start "other-instances" > > On each instance, create 2 new databases "input" and "output", load a file > in "input", process it and store result in "output". The process queries a > lot "library", but never modifies "library". Then export "output" and drop > databases "input" and "output". I have about 100 files to process; and I > distribute them on the various instances > > I had a first test environment, with only 4 isntances, and everything was > working perfectly. > Now, I'm working on target environment, a bigger computer with 8 instances. > Process fails, at least one time per instance, so between 8 and 12 times on > 100 process. The exception is > java.lang.NullPointerException > at org.basex.data.DiskData.write(DiskData.java:136) > at org.basex.data.DiskData.close(DiskData.java:151) > at org.basex.core.Datas.unpin(Datas.java:54) > at org.basex.core.cmd.Close.close(Close.java:45) > at org.basex.query.QueryResources.close(QueryResources.java:110) > at org.basex.query.QueryContext.close(QueryContext.java:596) > at org.basex.query.QueryProcessor.close(QueryProcessor.java:251) > at org.basex.core.cmd.AQuery.query(AQuery.java:124) > at org.basex.core.cmd.XQuery.run(XQuery.java:22) > at org.basex.core.Command.run(Command.java:398) > at org.basex.core.Command.execute(Command.java:100) > at org.basex.server.ClientListener.run(ClientListener.java:136) > > If I change the sym-links by a true copy (cp -r main/data/library > other/data/), it now works correctly, but the copy takes a long time > (database is about 30gb), and it consumes disk space. > The computer I use has many available cores, and many RAM to use, so I'd > love to add other instance, many 16 more to reach 24 isntances, but if > database grow, I'm going to have disk-space troubles... > > 1 - is it legal to share a database (and files) between many instances as > far as database is access read-only ? > 2 - is there a way to configure a database to be read-only ? > 3 - why symbolic links were perfectly usable with 4 instances, and do not > with 8 instances ? (Hum I have to try symlinks with only 4 instances on the > new computer...) > 4 - are there other specific things to check to do what I need ? > > Best regards, > Christophe > > > -- > Dirk Kirsten, BaseX GmbH, http://basexgmbh.de > |-- Firmensitz: Blarerstrasse 56, 78462 Konstanz > |-- Registergericht Freiburg, HRB: 708285, Geschäftsführer: > | Dr. Christian Grün, Dr. Alexander Holupirek, Michael Seiferle > `-- Phone: 0049 7531 91 68 276, Fax: 0049 7531 20 05 22
