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 18 in 1 sec
Finally, the database can be shut down again:
managementService.shutdown();
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