Multiple-process access to BerkeleyDB

[Shyam Santhanam]

Hi,

I'm trying to use BerkeleyDB with Titan where I can have multiple processes accessing the same database instance, specifically just one writer and one reader. The reader would be a Rexter instance, and the writer is embedded in my application. Can someone please explain how I can configure it do that? I am currently running into this error, which as I understand is because the EnvironmentConfig supplied when starting Berkeley DB does not have readOnly == false. Should we be matching EnvironmentConfig.readOnly to Titan's read-only configuration value?

274  [main] WARN  com.tinkerpop.rexster.config.GraphConfigurationContainer  - GraphConfiguration could not be found or otherwise instantiated: [com.thinkaurelius.titan.tinkerpop.rexster.TitanGraphConfiguration]. Ensure that it is in Rexster's path.

com.tinkerpop.rexster.config.GraphConfigurationException: GraphConfiguration could not be found or otherwise instantiated: [com.thinkaurelius.titan.tinkerpop.rexster.TitanGraphConfiguration]. Ensure that it is in Rexster's path.

at com.tinkerpop.rexster.config.GraphConfigurationContainer.getGraphFromConfiguration(GraphConfigurationContainer.java:142)

at com.tinkerpop.rexster.config.GraphConfigurationContainer.<init>(GraphConfigurationContainer.java:54)

at com.tinkerpop.rexster.server.XmlRexsterApplication.reconfigure(XmlRexsterApplication.java:99)

at com.tinkerpop.rexster.server.XmlRexsterApplication.<init>(XmlRexsterApplication.java:47)

at com.tinkerpop.rexster.Application.<init>(Application.java:97)

at com.tinkerpop.rexster.Application.main(Application.java:189)

Caused by: java.lang.IllegalArgumentException: Could not instantiate implementation: com.thinkaurelius.titan.diskstorage.berkeleyje.BerkeleyJEStoreManager

at com.thinkaurelius.titan.util.system.ConfigurationUtil.instantiate(ConfigurationUtil.java:55)

at com.thinkaurelius.titan.diskstorage.Backend.getImplementationClass(Backend.java:421)

at com.thinkaurelius.titan.diskstorage.Backend.getStorageManager(Backend.java:361)

at com.thinkaurelius.titan.graphdb.configuration.GraphDatabaseConfiguration.<init>(GraphDatabaseConfiguration.java:1275)

at com.thinkaurelius.titan.core.TitanFactory.open(TitanFactory.java:93)

at com.thinkaurelius.titan.core.TitanFactory.open(TitanFactory.java:73)

at com.thinkaurelius.titan.tinkerpop.rexster.TitanGraphConfiguration.configureGraphInstance(TitanGraphConfiguration.java:33)

at com.tinkerpop.rexster.config.GraphConfigurationContainer.getGraphFromConfiguration(GraphConfigurationContainer.java:124)

... 5 more

Caused by: java.lang.reflect.InvocationTargetException

at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)

at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)

at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)

at java.lang.reflect.Constructor.newInstance(Constructor.java:526)

at com.thinkaurelius.titan.util.system.ConfigurationUtil.instantiate(ConfigurationUtil.java:44)

... 12 more

Caused by: com.thinkaurelius.titan.diskstorage.PermanentBackendException: Error during BerkeleyJE initialization:

at com.thinkaurelius.titan.diskstorage.berkeleyje.BerkeleyJEStoreManager.initialize(BerkeleyJEStoreManager.java:108)

at com.thinkaurelius.titan.diskstorage.berkeleyje.BerkeleyJEStoreManager.<init>(BerkeleyJEStoreManager.java:68)

... 17 more

Caused by: com.sleepycat.je.EnvironmentLockedException: (JE 5.0.73) /tmp/titan The environment cannot be locked for single writer access. ENV_LOCKED: The je.lck file could not be locked. Environment is invalid and must be closed.

at com.sleepycat.je.log.FileManager.<init>(FileManager.java:371)

at com.sleepycat.je.dbi.EnvironmentImpl.<init>(EnvironmentImpl.java:453)

at com.sleepycat.je.dbi.EnvironmentImpl.<init>(EnvironmentImpl.java:382)

at com.sleepycat.je.dbi.DbEnvPool.getEnvironment(DbEnvPool.java:178)

at com.sleepycat.je.Environment.makeEnvironmentImpl(Environment.java:246)

at com.sleepycat.je.Environment.<init>(Environment.java:227)

at com.sleepycat.je.Environment.<init>(Environment.java:170)

at com.thinkaurelius.titan.diskstorage.berkeleyje.BerkeleyJEStoreManager.initialize(BerkeleyJEStoreManager.java:104)

... 18 more

Thanks,

Shyam

[Matthias Broecheler]

No, I think you will need to extend the current BerkeleyJE adapter to allow this since it requires a different environment setup if I remember correctly. Currently, BerkeleyJE is used mostly for inprocess data stores - hence that default.

HTH,

Matthias

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Matthias Broecheler
http://www.matthiasb.com