AFAIK there are no differences between the two. The read-only version makes sure you cannot perform modifications to the graph, but otherwise they use the same calls and code.
Regarding the NonWritableChannelException. I see that FileChannel.write() is called (even though nothing has changed), even when in read-only mode when releasing persistence windows for the persistence window implementation used for windows/non-memory-mapped environments. That should be the culprit in here. I'll try to reproduce it locally. 2011/6/29 Paul Bandler <[email protected]> > The problem resulting in the NonWritableChannelException occurred on > Windows although I need to run on Solaris as well as Windows. > > Actually I must apologise for saying that the previously reported issue > didn't solicit a response - I see that Johan Svensson did just today and > suggests it might be fixed in the new milestone release. > > My questions regarding what actual effect using the > EmbeddedReadOnlyGraphDatabase is still relevant however...? > > On 28 Jun 2011, at 21:21, Rick Bullotta wrote: > > > Paul, are you on windows or Linux? > > > > ----- Reply message ----- > > From: "Paul Bandler" <[email protected]> > > Date: Tue, Jun 28, 2011 1:34 pm > > Subject: [Neo4j] Advantages of EmbeddedReadOnlyGraphDatabase ? [was > NonWritableChannelException] > > To: "Neo4j user discussions" <[email protected]> > > > > Are there advantages in accessing the database via the > EmbeddedReadOnlyGraphDatabaseclass in a read-only application? > > > > A week or so back I posted the message below regarding a problem > experienced while using EmbeddedReadOnlyGraphDatabase that regrettably > didn't solicit any responses and since then I've been using the standard > read-write EmbeddedGraphDatabase without repeat of the same issue even > though my application is read-only. Are there any avoidable performance > penalties using EmbeddedGraphDatabase in place of > EmbeddedReadOnlyGraphDatabase? > > > > Along a similar lines, as my application is read-only, I'm not doing any > explicit transaction management - is there any reason why I should? > > > > > > > > Begin forwarded message: > > > > > From: Paul Bandler <[email protected]> > > > Date: 21 June 2011 12:22:56 GMT+01:00 > > > To: Neo4j user discussions <[email protected]> > > > Subject: [Neo4j] NonWritableChannelException > > > Reply-To: Neo4j user discussions <[email protected]> > > > > > > The above exception is thrown from the call stack indicated below while > traversing a neo4j graph using the EmbededReadOnly database. Using 1.4M04. > > > > > > The application is running with 1gb of heap with defaulting all other > parameters except cache_type=weak on windows. > > > > > > I found some reports of this exception being thrown at shutdown back > > > in January but this is not happening at shutdown and I could find no > posted resolution of that thread anyway. > > > > > > Can anyone suggest what the cause if this exception is? > > > > > > Thanks > > > > > > Paul > > > > > >> > > > > > >> Exception in thread "main" > java.nio.channels.NonWritableChannelException > > >> at sun.nio.ch.FileChannelImpl.write(Unknown Source) > > >> at > org.neo4j.kernel.impl.nioneo.store.AbstractPersistenceWindow.writeOut(AbstractPersistenceWindow.java:104) > > >> at > org.neo4j.kernel.impl.nioneo.store.PersistenceWindowPool.refreshBricks(PersistenceWindowPool.java:536) > > >> at > org.neo4j.kernel.impl.nioneo.store.PersistenceWindowPool.acquire(PersistenceWindowPool.java:128) > > >> at > org.neo4j.kernel.impl.nioneo.store.CommonAbstractStore.acquireWindow(CommonAbstractStore.java:526) > > >> at > org.neo4j.kernel.impl.nioneo.store.RelationshipStore.getChainRecord(RelationshipStore.java:327) > > >> at > org.neo4j.kernel.impl.nioneo.xa.ReadTransaction.getMoreRelationships(ReadTransaction.java:114) > > >> at > org.neo4j.kernel.impl.nioneo.xa.ReadTransaction.getMoreRelationships(ReadTransaction.java:97) > > >> at > org.neo4j.kernel.impl.persistence.PersistenceManager.getMoreRelationships(PersistenceManager.java:108) > > >> at > org.neo4j.kernel.impl.core.NodeManager.getMoreRelationships(NodeManager.java:603) > > >> at > org.neo4j.kernel.impl.core.NodeImpl.getMoreRelationships(NodeImpl.java:399) > > >> at > org.neo4j.kernel.impl.core.IntArrayIterator.hasNext(IntArrayIterator.java:93) > > >> at > org.neo4j.kernel.impl.core.NodeImpl.getSingleRelationship(NodeImpl.java:218) > > >> > > > _______________________________________________ > > > Neo4j mailing list > > > [email protected] > > > https://lists.neo4j.org/mailman/listinfo/user > > > > _______________________________________________ > > Neo4j mailing list > > [email protected] > > https://lists.neo4j.org/mailman/listinfo/user > > _______________________________________________ > Neo4j mailing list > [email protected] > https://lists.neo4j.org/mailman/listinfo/user > -- Mattias Persson, [[email protected]] Hacker, Neo Technology www.neotechnology.com _______________________________________________ Neo4j mailing list [email protected] https://lists.neo4j.org/mailman/listinfo/user
