Re: [Neo4j] Neo4j + Rexster lock problem

[Peter Neubauer]

Sulabh,
do you have the setup somewhere? This should not be a problem per se, so I
think there is some multiple booting of Neo4j going on ... can try to help
you off-list with that and get back with the results here.

Cheers,

/peter neubauer

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On Wed, May 11, 2011 at 9:33 AM, sulabh choudhury sula...@gmail.com wrote:

 A similar question has been asked previously but I could not find a
 solution which would work for me, hence re-posting it.

 I am creating a Neo4j graph and want to expose it over REST using Rexster
 so that I can apply traversals to it.
 Now after I have started Rexster, I see that I cannot write to the graph as
 it throws the java.lang.IllegalStateException: Unable to lock store
 [complete_graph//neostore], this is usually a result of some other Neo4j
 kernel running using the same store.

 So does this mean everytime I have to write to the graph I have to shut
 down Rexster (hence disabling my traversals) and then start it again after I
 finish writing to it?
 I read somewhere that you cannot start multiple  services to same store in
 write mode, so is there a way where I can expose it over Rexster just in
 read mode and perform traversals ?

 Or is there any way around this problem ?

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Re: [Neo4j] Neo4j + Rexster lock problem

[Marko Rodriguez]

Hi Sulabh,

You can only have one instance of Neo4j over a particular directory. As such, 
when you want to have multiple threads talking to a single Neo4j, you will need 
to pass that reference around to each thread.

Thus, when Rexster is running over Neo4j, Rexster has that reference. To have 
other threads/software talk to Neo4j via Rexster, you can talk to it with:

1. The RESTful interface: 
https://github.com/tinkerpop/rexster/wiki/Basic-REST-API
2. Via Gremlin: https://github.com/tinkerpop/rexster/wiki/Using-Gremlin 
3. By writing an Extension (Rexster-Kibble): 
https://github.com/tinkerpop/rexster/wiki/Creating-an-Extension
https://github.com/tinkerpop/rexster-kibbles/wiki

In other words, its illegal to do this:

g1 = new Neo4jGraph('/tmp/graph');
g2 = new Neo4jGraph('/tmp/graph');

You get the Unable to lock store exception. However you can do this:

g = new Neo4jGraph('/tmp/graph');
createThreadAndProcessGraph(g);

It all comes down to reference to the original instance.

Thanks,
Marko.

http://markorodriguez.com

On May 11, 2011, at 11:33 AM, sulabh choudhury wrote:

 A similar question has been asked previously but I could not find a solution 
 which would work for me, hence re-posting it.
 
 I am creating a Neo4j graph and want to expose it over REST using Rexster so 
 that I can apply traversals to it.
 Now after I have started Rexster, I see that I cannot write to the graph as 
 it throws the java.lang.IllegalStateException: Unable to lock store 
 [complete_graph//neostore], this is usually a result of some other Neo4j 
 kernel running using the same store.
 
 So does this mean everytime I have to write to the graph I have to shut down 
 Rexster (hence disabling my traversals) and then start it again after I 
 finish writing to it?
 I read somewhere that you cannot start multiple  services to same store in 
 write mode, so is there a way where I can expose it over Rexster just in read 
 mode and perform traversals ?
 
 Or is there any way around this problem ?

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Re: [Neo4j] Neo4j + Rexster lock problem

[Peter Neubauer]

For such a situation,
you should use the Neoj4 HA cluster, which will manage the propagation of
data between the different instances for you. I think that is the cleanest
and best solution here.

Cheers,

/peter neubauer

GTalk:  neubauer.peter
Skype   peter.neubauer
Phone   +46 704 106975
LinkedIn   http://www.linkedin.com/in/neubauer
Twitter  http://twitter.com/peterneubauer

http://www.neo4j.org   - Your high performance graph database.
http://startupbootcamp.org/- Öresund - Innovation happens HERE.
http://www.thoughtmade.com - Scandinavia's coolest Bring-a-Thing party.


On Wed, May 11, 2011 at 11:34 AM, Marko Rodriguez okramma...@gmail.comwrote:

 Hi Sulabh,

 You can only have one instance of Neo4j over a particular directory. As
 such, when you want to have multiple threads talking to a single Neo4j, you
 will need to pass that reference around to each thread.

 Thus, when Rexster is running over Neo4j, Rexster has that reference. To
 have other threads/software talk to Neo4j via Rexster, you can talk to it
 with:

 1. The RESTful interface:
 https://github.com/tinkerpop/rexster/wiki/Basic-REST-API
  2. Via Gremlin: https://github.com/tinkerpop/rexster/wiki/Using-Gremlin
 3. By writing an Extension (Rexster-Kibble):
 https://github.com/tinkerpop/rexster/wiki/Creating-an-Extension
  https://github.com/tinkerpop/rexster-kibbles/wiki

 In other words, its illegal to do this:

 g1 = new Neo4jGraph('/tmp/graph');
 g2 = new Neo4jGraph('/tmp/graph');

 You get the Unable to lock store exception. However you can do this:

 g = new Neo4jGraph('/tmp/graph');
 createThreadAndProcessGraph(g);

 It all comes down to reference to the original instance.

 Thanks,
 Marko.

 http://markorodriguez.com

 On May 11, 2011, at 11:33 AM, sulabh choudhury wrote:

 A similar question has been asked previously but I could not find a
 solution which would work for me, hence re-posting it.

 I am creating a Neo4j graph and want to expose it over REST using Rexster
 so that I can apply traversals to it.
 Now after I have started Rexster, I see that I cannot write to the graph as
 it throws the java.lang.IllegalStateException: Unable to lock store
 [complete_graph//neostore], this is usually a result of some other Neo4j
 kernel running using the same store.

 So does this mean everytime I have to write to the graph I have to shut
 down Rexster (hence disabling my traversals) and then start it again after I
 finish writing to it?
 I read somewhere that you cannot start multiple  services to same store in
 write mode, so is there a way where I can expose it over Rexster just in
 read mode and perform traversals ?

 Or is there any way around this problem ?



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