Terminating a running transaction

The section describes how to terminate (abort) a long-running transaction from another thread.

The source code used in this example is found here: TerminateTransactions.java

First, start the database server:

DatabaseManagementService managementService = new DatabaseManagementServiceBuilder( databaseDirectory ).build();
GraphDatabaseService graphDb = managementService.database( DEFAULT_DATABASE_NAME );

Then start creating an infinite binary tree of nodes in the database, as an example of a long-running transaction:

RelationshipType relType = RelationshipType.withName( "CHILD" );
Queue<Node> nodes = new LinkedList<>();
int depth = 1;

try ( Transaction tx = graphDb.beginTx() )
{
    Node rootNode = tx.createNode();
    nodes.add( rootNode );

    for (; true; depth++) {
        int nodesToExpand = nodes.size();
        for (int i = 0; i < nodesToExpand; ++i) {
            Node parent = nodes.remove();

            Node left = tx.createNode();
            Node right = tx.createNode();

            parent.createRelationshipTo( left, relType );
            parent.createRelationshipTo( right, relType );

            nodes.add( left );
            nodes.add( right );
        }
    }
}
catch ( TransactionTerminatedException ignored )
{
    return String.format( "Created tree up to depth %s in 1 sec", depth );
}

After waiting for some time, you decide to terminate the transaction. This is done from a separate thread:

tx.terminate();

Running this will execute the long-running transaction for about one second and prints the maximum depth of the tree that was created before the transaction was terminated. No changes are actually made to the data — because the transaction has been terminated, the end result is as if no operations were performed.

This is an example output:

Created tree up to depth 17 in 1 sec

Finally, the database can be shut down again:

managementService.shutdown();