Error Obtaining Lock (org.neo4j.kernal.StoreLockException)

Question

When trying to create new nodes in an already existing database, I am getting the following exception:

org.neo4j.kernal.StoreLockException.

The code snippit below is the actual line that results in the exception. Below that I have attached some more detail and the full stack trace.

If I create a new folder and use that as the DB_PATH, then my code works fine on the first run. On the second run, it will fail with the same exception. It appears something is preventing the lock from being obtained.

I tried to set permissions to Read/Write on every file in the DB_PATH. No luck. Is there a setting in one of the config files that must be disabled with regard to locks?

Code Throwing Exception

graphDB = new GraphDatabaseFactory().newEmbeddedDatabase( DB_PATH );

More Detail (Line 6)

private static GraphDatabaseService graphDB = null;
public static final String DB_PATH = "/Users/NtroduceMe/Downloads/neo4j-community-2.0.0-M03/data/ntroduceme";
private static Index<Node> userNodeIndex;
private static Index<Node> rememberMeNodeIndex;
static {
    graphDB = new GraphDatabaseFactory().newEmbeddedDatabase( DB_PATH );
    registerShutdownHook(graphDB);
    userNodeIndex = graphDB.index().forNodes("profile_id");
    rememberMeNodeIndex = graphDB.index().forNodes("profile_id");
}

Stack Trace

Jun 19, 2013 12:12:50 AM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [ProfileController] in context with path [] threw exception [Servlet execution threw an exception] with root cause
org.neo4j.kernel.StoreLockException: Could not create lock file
    at org.neo4j.kernel.StoreLocker.checkLock(StoreLocker.java:85)
    at org.neo4j.kernel.StoreLockerLifecycleAdapter.start(StoreLockerLifecycleAdapter.java:40)
    at org.neo4j.kernel.lifecycle.LifeSupport$LifecycleInstance.start(LifeSupport.java:498)
    at org.neo4j.kernel.lifecycle.LifeSupport.start(LifeSupport.java:115)
    at org.neo4j.kernel.InternalAbstractGraphDatabase.run(InternalAbstractGraphDatabase.java:296)
    at org.neo4j.kernel.EmbeddedGraphDatabase.<init>(EmbeddedGraphDatabase.java:100)
    at org.neo4j.graphdb.factory.GraphDatabaseFactory$1.newDatabase(GraphDatabaseFactory.java:92)
    at org.neo4j.graphdb.factory.GraphDatabaseBuilder.newGraphDatabase(GraphDatabaseBuilder.java:197)
    at org.neo4j.graphdb.factory.GraphDatabaseFactory.newEmbeddedDatabase(GraphDatabaseFactory.java:69)
    at com.NtroduceMe.Utilities.GraphDBManager.<clinit>(GraphDBManager.java:22)
    at com.NtroduceMe.UserProfile.Profiles.createProfile(Profiles.java:141)
    at com.NtroduceMe.UserProfile.ProfileController.doPost(ProfileController.java:61)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:647)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:936)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1004)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:722)

Helper Class I use to Store the Database Instance

public class GraphDBManager {
    public static final String DB_PATH = "/Users/NtroduceMe/Downloads/neo4j-community-2.0.0-M03/data/ntroduceme";
    private static final GraphDatabaseService graphDB = new GraphDatabaseFactory().newEmbeddedDatabase( DB_PATH );    
    private static Index<Node> userNodeIndex;
    private static Index<Node> rememberMeNodeIndex;
    static {
        registerShutdownHook(graphDB);
        userNodeIndex = graphDB.index().forNodes("profile_id");
        rememberMeNodeIndex = graphDB.index().forNodes("profile_id");
    }

    public static GraphDatabaseService getGraphDB(){
        return graphDB;
    }

    public static Index<Node> getUserNodeIndex(){
        return userNodeIndex;
    }

    public static Index<Node> getRemberMeNodeIndex(){
        return rememberMeNodeIndex;
    }

    private static void registerShutdownHook(final GraphDatabaseService graphDb )
    {
        // Registers a shutdown hook for the Neo4j instance so that it
        // shuts down nicely when the VM exits (even if you "Ctrl-C" the
        // running application).
        Runtime.getRuntime().addShutdownHook( new Thread()
        {
            @Override
            public void run()
            {
                graphDb.shutdown();
            }
        } );
    }   

}

Answer 1

You aren't properly shutting down your database when the program is ending, so it's leaving the lock file there.

You might consider setting up a shutdown hook as described here: http://docs.neo4j.org/chunked/stable/tutorials-java-embedded-setup.html#tutorials-java-embedded-setup-startstop

Answer 2

I just wonder why you shutdown the DB before creating the nodes ?

You can't create nodes using a closed DB, so it can be like that:

 graphDB = new GraphDatabaseFactory().newEmbeddedDatabase( DB_PATH );
 userNodeIndex = graphDB.index().forNodes("profile_id");
 rememberMeNodeIndex = graphDB.index().forNodes("profile_id");
 Transaction tx = graphDb.beginTx();
 try
    {
    Node node = graphDb.createNode();
    node.setProperty( USER_ID, "userID");
    nodeIndex.add( node, USER_ID, "userID" );
    }

and after you fininsh creating all nodes, you can call:

   registerShutdownHook(graphDB);