I am getting too many deadlocks on OrientDb while I am using Java API to query the vertices. After the deadlock happens, the entire database becomes unresponsive and I have to kill the daemon and start again. As example, the error that I get from deadlocks is :
com.orientechnologies.common.concur.OTimeoutException: Can not lock record for 2000 ms. seems record is deadlocked by other record
at com.orientechnologies.orient.core.storage.impl.local.OAbstractPaginatedStorage.acquireReadLock(OAbstractPaginatedStorage.java:1300)
at com.orientechnologies.orient.core.tx.OTransactionAbstract.lockRecord(OTransactionAbstract.java:120)
at com.orientechnologies.orient.core.id.ORecordId.lock(ORecordId.java:282)
at com.orientechnologies.orient.core.storage.impl.local.OAbstractPaginatedStorage.lockRecord(OAbstractPaginatedStorage.java:1776)
at com.orientechnologies.orient.core.storage.impl.local.OAbstractPaginatedStorage.readRecord(OAbstractPaginatedStorage.java:1416)
at com.orientechnologies.orient.core.storage.impl.local.OAbstractPaginatedStorage.readRecord(OAbstractPaginatedStorage.java:694)
at com.orientechnologies.orient.core.db.document.ODatabaseDocumentTx.executeReadRecord(ODatabaseDocumentTx.java:1569)
at com.orientechnologies.orient.core.tx.OTransactionNoTx.loadRecord(OTransactionNoTx.java:80)
at com.orientechnologies.orient.core.db.document.ODatabaseDocumentTx.load(ODatabaseDocumentTx.java:1434)
at com.orientechnologies.orient.server.network.protocol.binary.ONetworkProtocolBinary.readRecord(ONetworkProtocolBinary.java:1456)
at com.orientechnologies.orient.server.network.protocol.binary.ONetworkProtocolBinary.executeRequest(ONetworkProtocolBinary.java:346)
at com.orientechnologies.orient.server.network.protocol.binary.OBinaryNetworkProtocolAbstract.execute(OBinaryNetworkProtocolAbstract.java:216)
at com.orientechnologies.common.thread.OSoftThread.run(OSoftThread.java:65)
Following is the block that I use to query edges and create associations between vertices
public User generateFriend(String mobile, String userRID) {
StringBuilder errorMsg = new StringBuilder();
Iterable<OrientVertex> vertexes;
//Retrieve friends of the user
List<User> friendsList = new ArrayList<User>();
vertexes = db.queryVertices("select expand( unionAll(inE('E_Friend').out,outE('E_Friend').in) ) from " + userRID,errorMsg);
if (!errorMsg.toString().equals("")) {
throw new DbException("Db exception occured, " + errorMsg);
}
for (OrientVertex v : vertexes){
friendsList.add(vertexToUser(v));
}
//Create edges if between the user and other users with mobile number in the list and if the edge is not yet created
User u = findUserByMobileNo(friendsList,mobile);
if ( u == null){
u = findByMobileNo(mobile);
if (u != null) {
//create edge
db.executeQuery("select createEdge('E_Friend','" + userRID + "','" + u.getRid() + "') from " + userRID, new HashMap<String, Object>(), errorMsg);
if (!errorMsg.toString().equals("")) {
throw new DbException("Db exception occured, " + errorMsg);
}
}
}
return u;
}
public Iterable<OrientVertex> queryVertices(String query, StringBuilder errMsg){
logger.error("before getGraph, " + errMsg.toString());
graph = getGraph(errMsg);
if (!errMsg.toString().equals("")){
return null;
}
logger.error("after getGraph, " + errMsg.toString());
Iterable<OrientVertex> vertices = null;
try {
OSQLSynchQuery<OrientVertex> qr = new OSQLSynchQuery<OrientVertex>(query);
vertices = graph.command(qr).execute();
logger.error("after graph command execute, " + errMsg.toString());
}
catch (Exception ex){
errMsg.append(ex.getMessage());
logger.error("graph command exception, " + errMsg.toString());
}
logger.error("before return vertices, " + errMsg.toString());
return vertices;
}
public List<ODocument> executeQuery(String sql, HashMap<String,Object> params,StringBuilder errMsg) {
List<ODocument> result = new ArrayList<ODocument>();
try {
db = getDatabase(errMsg);
if (!errMsg.toString().equals("")){
return null;
}
OSQLSynchQuery<ODocument> query = new OSQLSynchQuery<ODocument>(sql);
if (params.isEmpty()) {
result = db.command(query).execute();
} else {
result = db.command(query).execute(params);
}
} catch (Exception e) {
errMsg.append(e.getMessage());
//TODO: Add threaded error log saving mechanism
}
return result;
}
