OConcurrentModificationException while adding edges - graph

Question

We're developing a system that we're basing on OrientDB graphs (OrientDB 2.1.3). In the application, we have a thin pojo->graph persistence layer that should do the work properly, but I get OConcurrentModificationException when having multiple threads updating the database.
Here's an example scenario:
Create a Product vertex with edge to Color "Blue"
Simultaneously (while the transaction for creating Product 1 is open) create another Product vertex is created and also adds an edge to Color "Blue".
OConcurrentModificationException is thrown since the version of Color "Blue" vertex is updated. Note that I'm not trying to save or modify the Color "Blue" vertex itself.
As I understood the docs at http://orientdb.com/docs/2.1/Concurrency.html#concurrency-on-adding-edges setting -DridBag.embeddedToSbtreeBonsaiThreshold=-1 should help me avoid my problem, although it still doesn't work.
What am I missing? Is there anything else I can do to avoid this?
Update:
Stacktrace of the exception:
Error on releasing database 'infogileorientdatabasetest' in pool
com.orientechnologies.orient.core.exception.OConcurrentModificationException: Cannot UPDATE the record #40:1 because the version is not the latest. Probably you are updating an old record or it has been modified by another user (db=v34 your=v33)
at com.orientechnologies.orient.core.conflict.OVersionRecordConflictStrategy.checkVersions(OVersionRecordConflictStrategy.java:55)
at com.orientechnologies.orient.core.conflict.OVersionRecordConflictStrategy.onUpdate(OVersionRecordConflictStrategy.java:42)
at com.orientechnologies.orient.core.storage.impl.local.OAbstractPaginatedStorage.checkAndIncrementVersion(OAbstractPaginatedStorage.java:2279)
at com.orientechnologies.orient.core.storage.impl.local.OAbstractPaginatedStorage.doUpdateRecord(OAbstractPaginatedStorage.java:1911)
at com.orientechnologies.orient.core.storage.impl.local.OAbstractPaginatedStorage.commitEntry(OAbstractPaginatedStorage.java:2364)
at com.orientechnologies.orient.core.storage.impl.local.OAbstractPaginatedStorage.commit(OAbstractPaginatedStorage.java:1111)
at com.orientechnologies.orient.core.tx.OTransactionOptimistic.doCommit(OTransactionOptimistic.java:609)
at com.orientechnologies.orient.core.tx.OTransactionOptimistic.commit(OTransactionOptimistic.java:156)
at com.orientechnologies.orient.core.db.document.ODatabaseDocumentTx.commit(ODatabaseDocumentTx.java:2582)
at com.orientechnologies.orient.core.db.document.ODatabaseDocumentTx.commit(ODatabaseDocumentTx.java:2551)
at com.orientechnologies.orient.server.network.protocol.binary.ONetworkProtocolBinary.commit(ONetworkProtocolBinary.java:1221)
at com.orientechnologies.orient.server.network.protocol.binary.ONetworkProtocolBinary.executeRequest(ONetworkProtocolBinary.java:400)
at com.orientechnologies.orient.server.network.protocol.binary.OBinaryNetworkProtocolAbstract.execute(OBinaryNetworkProtocolAbstract.java:223)
at com.orientechnologies.common.thread.OSoftThread.run(OSoftThread.java:77)
Update 2 - test case
I have reproduced the error using this test case. I would be delighted if there's something else I've done wrong to cause the problem... :-)
Update 3 Updated test case with OGlobalConfiguration.RID_BAG_EMBEDDED_TO_SBTREEBONSAI_THRESHOLD.setValue(-1) in a static block.
package se.infogile.persistence.orientdb;
import com.orientechnologies.orient.client.remote.OServerAdmin;
import com.orientechnologies.orient.core.config.OGlobalConfiguration;
import com.orientechnologies.orient.core.db.OPartitionedDatabasePool;
import com.orientechnologies.orient.core.db.OPartitionedDatabasePoolFactory;
import com.orientechnologies.orient.core.db.document.ODatabaseDocumentTx;
import com.orientechnologies.orient.core.exception.OConcurrentModificationException;
import com.orientechnologies.orient.core.exception.OConfigurationException;
import com.orientechnologies.orient.core.exception.OStorageException;
import com.orientechnologies.orient.core.tx.OTransaction;
import com.orientechnologies.orient.enterprise.channel.binary.OResponseProcessingException;
import com.orientechnologies.orient.server.OServer;
import com.orientechnologies.orient.server.OServerMain;
import com.orientechnologies.orient.server.config.OServerConfiguration;
import com.orientechnologies.orient.server.config.OServerConfigurationLoaderXml;
import com.orientechnologies.orient.server.config.OServerNetworkListenerConfiguration;
import com.tinkerpop.blueprints.Vertex;
import com.tinkerpop.blueprints.impls.orient.OrientGraph;
import org.apache.commons.io.FileUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.testng.Assert;
import org.testng.annotations.AfterSuite;
import org.testng.annotations.BeforeSuite;
import org.testng.annotations.Test;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.*;
/**
* Created by heintz on 14/10/15.
*/
public class OrientDBEdgeProblemTest {
static {
OGlobalConfiguration.RID_BAG_EMBEDDED_TO_SBTREEBONSAI_THRESHOLD.setValue(-1);
}
private static OPartitionedDatabasePoolFactory dbPoolFactory = new OPartitionedDatabasePoolFactory(100);
private static Logger logger = LoggerFactory.getLogger(OrientDBEdgeProblemTest.class);
private OServer server = null;
private static ExecutorService executorService = Executors.newFixedThreadPool(10);
private static final String dbName = "edgeproblemtest";
#Test
public void testVersionIncrementError() throws Throwable {
OrientGraph graph = getGraph(dbName);
graph.getRawGraph().setDefaultTransactionMode();
graph.createVertexType("Product");
graph.createVertexType("Color");
graph.createEdgeType("HasColor");
graph.getRawGraph().begin(OTransaction.TXTYPE.OPTIMISTIC);
// graph.begin();
Vertex v1 = graph.addVertex("Color", "name", "Blue");
graph.commit();
graph.shutdown();
char[] alphabet = new char[] {'A','B','C','D','E','F','G'};
List<Future> futures = new ArrayList<>();
for (int i = 0; i < 2; i++) {
int pos = i;
futures.add(executorService.submit(new Callable<Object>() {
#Override
public Object call() throws Exception {
OrientGraph g = getGraph(dbName);
try {
g.begin();
Vertex v2 = g.addVertex("Product", "name", "Product "+alphabet[pos]);
g.addEdge(null, v2, v1, "HasColor");
Thread.sleep(200);
g.commit();
} catch (OConcurrentModificationException ocme) {
logger.error("Exception while saving: ", ocme);
Assert.fail("OConcurrentModificationException");
} finally {
g.shutdown();
}
return null;
}
}));
}
for (Future f : futures) {
f.get();
}
executorService.shutdown();
executorService.awaitTermination(5, TimeUnit.SECONDS);
}
#AfterSuite
public void tearDown() throws Exception {
logger.info("Shutting down OrientDB");
if (server != null) {
server.shutdown();
}
}
private OrientGraph getGraph(String dbName) {
String _db = "remote:localhost:3424";
String url = _db + "/" + dbName;
ODatabaseDocumentTx db = null;
try {
OPartitionedDatabasePool pool = dbPoolFactory.get(url,
"root",
"admin");
db = pool.acquire();
} catch (OResponseProcessingException | OConfigurationException | OStorageException oce) {
try {
logger.info("creating new database named " + dbName);
System.err.println("Before DB creation");
OServerAdmin serverAdmin = new OServerAdmin(_db).connect(
"root",
"admin"
);
serverAdmin.createDatabase(dbName, "document", "plocal");
serverAdmin.close();
System.err.println("After DB creation");
} catch (IOException ex) {
logger.error("Unable to create database " + dbName, ex);
}
OPartitionedDatabasePool pool = dbPoolFactory.get(url,
"root",
"admin");
db = pool.acquire();
}
return new OrientGraph(db);
}
#BeforeSuite
public void setUpDatabase() throws Exception {
File f = new File(".");
InputStream is = GraphPersistenceServiceTest.class.getResourceAsStream("/orientdb.config");
Assert.assertNotNull(is);
logger.info("Starting OrientDB");
server = OServerMain.create();
OServerConfigurationLoaderXml loaderXml = new OServerConfigurationLoaderXml(OServerConfiguration.class, GraphPersistenceServiceTest.class.getResourceAsStream("/orientdb.config"));
OServerConfiguration oServerConfiguration = new OServerConfiguration(loaderXml);
System.setProperty("ORIENTDB_ROOT_PASSWORD", "admin");
System.setProperty("RUNMODE", "UNITTEST");
OServerNetworkListenerConfiguration networkConfig = oServerConfiguration.network.listeners.iterator().next();
networkConfig.portRange = "3424-3430";
server.setServerRootDirectory("./target/orientdb");
server.startup(oServerConfiguration);
File serverDir = new File("./target/orientdb");
if (serverDir.exists()) {
FileUtils.deleteDirectory(serverDir);
}
serverDir.mkdirs();
File dbDir = new File(serverDir, "databases");
dbDir.mkdirs();
server.activate();
OGlobalConfiguration.dumpConfiguration(System.out);
Thread.sleep(2000);
}
}

Answer 1

Hi that is because when you add edges to the vertex, vertex itself is modified to store this information, but you may work in mode when information about edges is stored in separate object. Merely use property
-DridBag.embeddedToSbtreeBonsaiThreshold=true and you will rid off this exception.