[jira] [Created] (OAK-566) MongoMK throws exception when adding nodes concurrently

["Damien Obrist (JIRA)" <ji...@apache.org>]

Damien Obrist created OAK-566:
---------------------------------

             Summary: MongoMK throws exception when adding nodes concurrently
                 Key: OAK-566
                 URL: https://issues.apache.org/jira/browse/OAK-566
             Project: Jackrabbit Oak
          Issue Type: Bug
          Components: mongomk
            Reporter: Damien Obrist
            Priority: Minor


It seems that there is a problem in the MongoDB microkernel when lots of threads try to commit new nodes concurrently. I have attached a JUnit test which reproduces the error. The test creates 16 microkernels, each committing two nodes in a separate thread. Some threads will throw an exception saying that the node they're trying to commit already exists:

java.lang.RuntimeException: There's already a child node with name 'node6'
at org.apache.jackrabbit.mongomk.impl.instruction.CommitCommandInstructionVisitor.visit(CommitCommandInstructionVisitor.java:97)
at org.apache.jackrabbit.mongomk.impl.instruction.AddNodeInstructionImpl.accept(AddNodeInstructionImpl.java:40)
at org.apache.jackrabbit.mongomk.impl.command.CommitCommandNew.createMongoNodes(CommitCommandNew.java:155)
at org.apache.jackrabbit.mongomk.impl.command.CommitCommandNew.execute(CommitCommandNew.java:97)
at org.apache.jackrabbit.mongomk.impl.command.CommitCommandNew.execute(CommitCommandNew.java:1)
at org.apache.jackrabbit.mongomk.impl.command.DefaultCommandExecutor.execute(DefaultCommandExecutor.java:38)
at org.apache.jackrabbit.mongomk.impl.MongoNodeStore.commit(MongoNodeStore.java:110)
at org.apache.jackrabbit.mongomk.impl.MongoMicroKernel.commit(MongoMicroKernel.java:112)
... 7 more

This cannot be the case however, as the nodes added by the different threads do not overlap / conflict. No exceptions are thrown if setting the number of threads to some lower number, but I have observed that in this case the problem still exists when trying to add a larger number of nodes (more than just 2).

--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira