I am facing the following errors when i start the process

Exception in thread "main" javax.persistence.PersistenceException: [PersistenceUnit: org.jbpm.persistence.jpa] Unable to build EntityManagerFactory

          at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:677)

          at org.hibernate.ejb.HibernatePersistence.createEntityManagerFactory(HibernatePersistence.java:126)

          at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:52)

          at org.jbpm.test.JBPMHelper.loadStatefulKnowledgeSession(JBPMHelper.java:147)

          at org.jbpm.test.JBPMHelper.newStatefulKnowledgeSession(JBPMHelper.java:136)

          at com.sample.ProcessMain.main(ProcessMain.java:20)

Caused by: org.hibernate.HibernateException: Could not obtain BTM transaction manager instance

          at org.hibernate.transaction.BTMTransactionManagerLookup.getTransactionManager(BTMTransactionManagerLookup.java:50)

          at org.hibernate.impl.SessionFactoryImpl.<init>(SessionFactoryImpl.java:367)

          at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1341)

          at org.hibernate.cfg.AnnotationConfiguration.buildSessionFactory(AnnotationConfiguration.java:867)

          at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:669)

          ... 5 more

Caused by: java.lang.reflect.InvocationTargetException

          at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

          at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)

          at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)

          at java.lang.reflect.Method.invoke(Method.java:597)

          at org.hibernate.transaction.BTMTransactionManagerLookup.getTransactionManager(BTMTransactionManagerLookup.java:47)

          ... 9 more

Caused by: bitronix.tm.utils.InitializationException: cannot open disk journal

          at bitronix.tm.BitronixTransactionManager.<init>(BitronixTransactionManager.java:75)

          at bitronix.tm.TransactionManagerServices.getTransactionManager(TransactionManagerServices.java:62)

          ... 14 more

Caused by: java.io.IOException: The process cannot access the file because another process has locked a portion of the file

          at java.io.RandomAccessFile.read(Native Method)

          at java.io.RandomAccessFile.readInt(RandomAccessFile.java:720)

          at bitronix.tm.journal.TransactionLogHeader.<init>(TransactionLogHeader.java:96)

          at bitronix.tm.journal.TransactionLogAppender.<init>(TransactionLogAppender.java:69)

          at bitronix.tm.journal.DiskJournal.open(DiskJournal.java:151)

          at bitronix.tm.BitronixTransactionManager.<init>(BitronixTransactionManager.java:62)

          ... 15 more

The source code for this process is

Processmain.java ---

package com.sample;

import org.drools.KnowledgeBase;

import org.drools.builder.KnowledgeBuilder;

import org.drools.builder.KnowledgeBuilderFactory;

import org.drools.builder.ResourceType;

import org.drools.io.ResourceFactory;

import org.drools.runtime.StatefulKnowledgeSession;

import org.jbpm.test.JBPMHelper;

/**

* This is a sample file to launch a process.

*/

public class ProcessMain {

          public static final void main(String[] args) throws Exception {

                    startUp();

                    // load up the knowledge base

                    KnowledgeBase kbase = readKnowledgeBase();

                    StatefulKnowledgeSession ksession = JBPMHelper.newStatefulKnowledgeSession(kbase);

                    // start a new process instance

                    ksession.startProcess("com.sample.bpmn.hello");

                    System.out.println("Process started ...");

          }

          private static KnowledgeBase readKnowledgeBase() throws Exception {

                    KnowledgeBuilder kbuilder = KnowledgeBuilderFactory.newKnowledgeBuilder();

                    kbuilder.add(ResourceFactory.newClassPathResource("sample.bpmn"), ResourceType.BPMN2);

                    return kbuilder.newKnowledgeBase();

          }

          private static void startUp() {

                    JBPMHelper.startH2Server();

                    JBPMHelper.setupDataSource();

                    // please comment this line if you already have the task service running,

                    // for example when running the jbpm-installer

                    //JBPMHelper.startTaskService();

          }

}

ProcessTest.java -------

package com.sample;

import java.util.List;

import org.drools.runtime.StatefulKnowledgeSession;

import org.drools.runtime.process.ProcessInstance;

import org.jbpm.task.TaskService;

import org.jbpm.task.query.TaskSummary;

import org.jbpm.test.JbpmJUnitTestCase;

import org.junit.Test;

/**

* This is a sample file to launch a process.

*/

public class ProcessTest extends JbpmJUnitTestCase {

          public ProcessTest() {

                    super(true);

                    setPersistence(true);

          }

          @Test

          public void testProcess() {

                    StatefulKnowledgeSession ksession = createKnowledgeSession("sample.bpmn");

                    TaskService taskService = getTaskService(ksession);

                    ProcessInstance processInstance = ksession.startProcess("com.sample.bpmn.hello");

                    assertProcessInstanceActive(processInstance.getId(), ksession);

                    assertNodeTriggered(processInstance.getId(), "Start", "Task 1");

                    // let john execute Task 1

                    List<TaskSummary> list = taskService.getTasksAssignedAsPotentialOwner("john", "en-UK");

                    TaskSummary task = list.get(0);

                    System.out.println("John is executing task " + task.getName());

                    taskService.start(task.getId(), "john");

                    taskService.complete(task.getId(), "john", null);

                    assertNodeTriggered(processInstance.getId(), "Task 2");

                    // let mary execute Task 2

                    list = taskService.getTasksAssignedAsPotentialOwner("mary", "en-UK");

                    task = list.get(0);

                    System.out.println("Mary is executing task " + task.getName());

                    taskService.start(task.getId(), "mary");

                    taskService.complete(task.getId(), "mary", null);

                    assertNodeTriggered(processInstance.getId(), "End");

                    assertProcessInstanceCompleted(processInstance.getId(), ksession);

                    ksession.dispose();

          }

}