diff --git a/source/java/org/alfresco/repo/action/executer/MailActionExecuter.java b/source/java/org/alfresco/repo/action/executer/MailActionExecuter.java
index ad77d0b13b..82a01ea2a8 100644
--- a/source/java/org/alfresco/repo/action/executer/MailActionExecuter.java
+++ b/source/java/org/alfresco/repo/action/executer/MailActionExecuter.java
@@ -35,6 +35,7 @@ import java.util.Set;
 import javax.mail.MessagingException;
 import javax.mail.internet.MimeMessage;
 
+import org.alfresco.error.AlfrescoRuntimeException;
 import org.alfresco.model.ContentModel;
 import org.alfresco.repo.action.ParameterDefinitionImpl;
 import org.alfresco.repo.template.DateCompareMethod;
@@ -56,6 +57,7 @@ import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.commons.validator.EmailValidator;
 import org.springframework.beans.factory.InitializingBean;
+import org.springframework.mail.MailException;
 import org.springframework.mail.javamail.JavaMailSender;
 import org.springframework.mail.javamail.MimeMessageHelper;
 import org.springframework.mail.javamail.MimeMessagePreparator;
@@ -80,7 +82,7 @@ public class MailActionExecuter extends ActionExecuterAbstractBase
     public static final String PARAM_TEXT = "text";
     public static final String PARAM_FROM = "from";
     public static final String PARAM_TEMPLATE = "template";
-    
+       
     /**
      * From address
      */
@@ -138,6 +140,15 @@ public class MailActionExecuter extends ActionExecuterAbstractBase
      */
     private String repoRemoteUrl = null;
     
+    /**
+     * Test mode prevents email messages from being sent.
+     * It is used when unit testing when we don't actually want to send out email messages.
+     * 
+     * MER 20/11/2009 This is a quick and dirty fix. It should be replaced by being 
+     * "mocked out" or some other better way of running the unit tests. 
+     */
+    private boolean testMode = false;
+    
     /**
      * @param javaMailSender    the java mail sender
      */
@@ -236,7 +247,9 @@ public class MailActionExecuter extends ActionExecuterAbstractBase
     }
     
     /**
-     * Execute the rule action
+     * Send an email message
+     * 
+     * @throws AlfrescoRuntimeExeption
      */
     @Override
     protected void executeImpl(
@@ -375,15 +388,17 @@ public class MailActionExecuter extends ActionExecuterAbstractBase
                 }
             }
         };
-        
+                
         try
         {
-            // Send the message
-            javaMailSender.send(mailPreparer);
+            // Send the message unless we are in "testMode"
+            if(!testMode)
+            {
+                javaMailSender.send(mailPreparer);
+            }
         }
-        catch (Throwable e)
+        catch (MailException e)
         {
-            // don't stop the action but let admins know email is not getting sent
             String to = (String)ruleAction.getParameterValue(PARAM_TO);
             if (to == null)
             {
@@ -395,6 +410,8 @@ public class MailActionExecuter extends ActionExecuterAbstractBase
             }
             
             logger.error("Failed to send email to " + to, e);
+            
+            throw new AlfrescoRuntimeException("Failed to send email to:" + to, e);   
         }
     }
     
@@ -461,6 +478,16 @@ public class MailActionExecuter extends ActionExecuterAbstractBase
         paramList.add(new ParameterDefinitionImpl(PARAM_TEMPLATE, DataTypeDefinition.NODE_REF, false, getParamDisplayLabel(PARAM_TEMPLATE)));
     }
 
+    public void setTestMode(boolean testMode)
+    {
+        this.testMode = testMode;
+    }
+
+    public boolean isTestMode()
+    {
+        return testMode;
+    }
+
     public static class URLHelper
     {
         String contextPath;
diff --git a/source/java/org/alfresco/repo/invitation/InvitationServiceImplTest.java b/source/java/org/alfresco/repo/invitation/InvitationServiceImplTest.java
index dd5cf9d34f..0e35deb0f4 100644
--- a/source/java/org/alfresco/repo/invitation/InvitationServiceImplTest.java
+++ b/source/java/org/alfresco/repo/invitation/InvitationServiceImplTest.java
@@ -28,6 +28,7 @@ import java.util.Date;
 import java.util.List;
 
 import org.alfresco.model.ContentModel;
+import org.alfresco.repo.action.executer.MailActionExecuter;
 import org.alfresco.repo.security.authentication.AuthenticationComponent;
 import org.alfresco.repo.site.SiteModel;
 import org.alfresco.service.cmr.invitation.Invitation;
@@ -78,11 +79,17 @@ public class InvitationServiceImplTest extends BaseAlfrescoSpringTest
     protected void onSetUpInTransaction() throws Exception
     {
         super.onSetUpInTransaction();
-        this.invitationService = (InvitationService)this.applicationContext.getBean("InvitationService");
-        this.siteService = (SiteService)this.applicationContext.getBean("SiteService");
-        this.personService = (PersonService)this.applicationContext.getBean("PersonService");
+        
+        this.invitationService = (InvitationService) this.applicationContext.getBean("InvitationService");
+        this.siteService = (SiteService) this.applicationContext.getBean("SiteService");
+        this.personService = (PersonService) this.applicationContext.getBean("PersonService");
         this.authenticationComponent = (AuthenticationComponent)this.applicationContext.getBean("authenticationComponent");
         
+        // TODO MER 20/11/2009 Bodge - turn off email sending to prevent errors during unit testing 
+        // (or sending out email by accident from tests)
+        MailActionExecuter mail = (MailActionExecuter)this.applicationContext.getBean("mail");
+        mail.setTestMode(true);
+        
         createPerson(USER_MANAGER, USER_MANAGER + "@alfrescotesting.com", PERSON_FIRSTNAME, PERSON_LASTNAME);
         createPerson(USER_ONE, USER_ONE_EMAIL,USER_ONE_FIRSTNAME, USER_ONE_LASTNAME);
         createPerson(USER_TWO, USER_TWO + "@alfrescotesting.com", PERSON_FIRSTNAME, PERSON_LASTNAME);
diff --git a/source/java/org/alfresco/repo/jscript/RhinoScriptProcessor.java b/source/java/org/alfresco/repo/jscript/RhinoScriptProcessor.java
index edd3f6eeec..c73ec95760 100644
--- a/source/java/org/alfresco/repo/jscript/RhinoScriptProcessor.java
+++ b/source/java/org/alfresco/repo/jscript/RhinoScriptProcessor.java
@@ -404,7 +404,6 @@ public class RhinoScriptProcessor extends BaseProcessor implements ScriptProcess
         model = convertToRhinoModel(model);
         
         Context cx = Context.enter();
-        cx.setOptimizationLevel(1);
         try
         {
             // Create a thread-specific scope from one of the shared scopes.
@@ -542,7 +541,7 @@ public class RhinoScriptProcessor extends BaseProcessor implements ScriptProcess
         try
         {
             cx.setWrapFactory(wrapFactory);
-            this.secureScope = cx.initStandardObjects();
+            this.secureScope = cx.initStandardObjects(null, true);
 
             // remove security issue related objects - this ensures the script may not access
             // unsecure java.* libraries or import any other classes for direct access - only
@@ -555,7 +554,7 @@ public class RhinoScriptProcessor extends BaseProcessor implements ScriptProcess
         {
             Context.exit();
         }
-
+        
         // Initialise the non-secure scope
         cx = Context.enter();
         try
@@ -564,7 +563,7 @@ public class RhinoScriptProcessor extends BaseProcessor implements ScriptProcess
 
             // allow access to all libraries and objects, including the importer
             // @see http://www.mozilla.org/rhino/ScriptingJava.html
-            this.nonSecureScope = new ImporterTopLevel(cx);
+            this.nonSecureScope = new ImporterTopLevel(cx, true);
         }
         finally
         {
diff --git a/source/java/org/alfresco/repo/site/SiteServiceImpl.java b/source/java/org/alfresco/repo/site/SiteServiceImpl.java
index 689463f973..59cb52ad3b 100644
--- a/source/java/org/alfresco/repo/site/SiteServiceImpl.java
+++ b/source/java/org/alfresco/repo/site/SiteServiceImpl.java
@@ -39,6 +39,7 @@ import java.util.concurrent.ConcurrentHashMap;
 
 import org.alfresco.model.ContentModel;
 import org.alfresco.repo.activities.ActivityType;
+import org.alfresco.repo.model.Repository;
 import org.alfresco.repo.search.QueryParameterDefImpl;
 import org.alfresco.repo.search.impl.lucene.LuceneQueryParser;
 import org.alfresco.repo.security.authentication.AuthenticationContext;
@@ -60,6 +61,8 @@ import org.alfresco.service.cmr.repository.NodeService;
 import org.alfresco.service.cmr.repository.StoreRef;
 import org.alfresco.service.cmr.search.QueryParameterDefinition;
 import org.alfresco.service.cmr.search.ResultSet;
+import org.alfresco.service.cmr.search.ResultSetRow;
+import org.alfresco.service.cmr.search.SearchParameters;
 import org.alfresco.service.cmr.search.SearchService;
 import org.alfresco.service.cmr.security.AccessPermission;
 import org.alfresco.service.cmr.security.AccessStatus;
@@ -1145,25 +1148,42 @@ public class SiteServiceImpl implements SiteService, SiteModel
     {
         boolean addUser = false;
         
-        NodeRef personRef = this.personService.getPerson(username);
-        Map<QName, Serializable> props = this.nodeService.getProperties(personRef);
-        String firstName = (String)props.get(ContentModel.PROP_FIRSTNAME);
-        String lastName = (String)props.get(ContentModel.PROP_LASTNAME);
-        final String lowFirstName = (firstName != null ? firstName.toLowerCase() : "");
-        final String lowLastName = (lastName != null ? lastName.toLowerCase() : "");
-        for (int i=0; i<nameFilters.length; i++)
+        String query = "+TYPE:\"cm:person\" +@cm\\:userName:\"" + username + "\"";
+        SearchParameters searchParameters = new SearchParameters();
+        searchParameters.setLanguage(SearchService.LANGUAGE_LUCENE);
+        searchParameters.addStore(StoreRef.STORE_REF_WORKSPACE_SPACESSTORE);
+        searchParameters.setQuery(query);        
+        ResultSet resultSet = this.searchService.query(searchParameters);
+        try
         {
-            if (lowFirstName.indexOf(nameFilters[i]) != -1)
+            if (resultSet.length() != 0)
             {
-                addUser = true;
-                break;
-            }
-            else if (lowLastName.indexOf(nameFilters[i]) != -1)
-            {
-                addUser = true;
-                break;
+                ResultSetRow row = resultSet.getRow(0);
+                Map<String, Serializable> values = row.getValues();
+                String firstName = (String)values.get(ContentModel.PROP_FIRSTNAME.toString());
+                String lastName = (String)values.get(ContentModel.PROP_LASTNAME.toString());
+                
+                final String lowFirstName = (firstName != null ? firstName.toLowerCase() : "");
+                final String lowLastName = (lastName != null ? lastName.toLowerCase() : "");
+                for (int i=0; i<nameFilters.length; i++)
+                {
+                    if (lowFirstName.indexOf(nameFilters[i]) != -1)
+                    {
+                        addUser = true;
+                        break;
+                    }
+                    else if (lowLastName.indexOf(nameFilters[i]) != -1)
+                    {
+                        addUser = true;
+                        break;
+                    }
+                }
             }
         }
+        finally
+        {
+            resultSet.close();
+        }
         
         return addUser;
     }
diff --git a/source/java/org/alfresco/repo/workflow/jbpm/AlfrescoJobExecutor.java b/source/java/org/alfresco/repo/workflow/jbpm/AlfrescoJobExecutor.java
index 7c55cea264..d6620f38e7 100644
--- a/source/java/org/alfresco/repo/workflow/jbpm/AlfrescoJobExecutor.java
+++ b/source/java/org/alfresco/repo/workflow/jbpm/AlfrescoJobExecutor.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2005-2007 Alfresco Software Limited.
+ * Copyright (C) 2005-2009 Alfresco Software Limited.
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
@@ -24,6 +24,7 @@
  */
 package org.alfresco.repo.workflow.jbpm;
 
+import org.alfresco.repo.lock.JobLockService;
 import org.alfresco.service.ServiceRegistry;
 import org.alfresco.service.transaction.TransactionService;
 import org.apache.commons.logging.Log;
@@ -43,23 +44,32 @@ import org.springmodules.workflow.jbpm31.JbpmFactoryLocator;
 public class AlfrescoJobExecutor extends JobExecutor
 {
     private static final long serialVersionUID = -4576396495395482111L;
-
+    
     private static Log log = LogFactory.getLog(JobExecutor.class);
     private TransactionService transactionService;
+    
     private JbpmConfiguration jbpmConfiguration;
-
+    
+    private JobLockService jobLockService;
+    private boolean jobExecutorLockEnabled = true;
+    
+    public void setJobExecutorLockEnabled(boolean jobExecutorLockEnabled)
+    {
+        this.jobExecutorLockEnabled = jobExecutorLockEnabled;
+    }
     
     /**
-     * Constructor
+     * Is Alfresco Job Executor Lock Enabled
+     * 
+     * @return true if only one executor thread allowed (including across cluster)
+     * 
+     * @since 3.2
      */
-    public AlfrescoJobExecutor()
+    public boolean getJobExecutorLockEnabled()
     {
-        BeanFactoryLocator factoryLocator = new JbpmFactoryLocator();
-        BeanFactoryReference factory = factoryLocator.useBeanFactory(null);
-        transactionService = (TransactionService)factory.getFactory().getBean(ServiceRegistry.TRANSACTION_SERVICE.getLocalName());
-        jbpmConfiguration = (JbpmConfiguration)factory.getFactory().getBean("jbpm_configuration");
+        return this.jobExecutorLockEnabled;
     }
-
+    
     /**
      * Gets Transaction Service
      * 
@@ -69,7 +79,34 @@ public class AlfrescoJobExecutor extends JobExecutor
     {
         return transactionService;
     }
-
+    
+    /**
+     * Gets Job Lock Service
+     * 
+     * @return  job lock service
+     * 
+     * @since 3.2
+     */
+    public JobLockService getJobLockService()
+    {
+        return jobLockService;
+    }
+    
+    /**
+     * Constructor
+     */
+    public AlfrescoJobExecutor()
+    {
+        BeanFactoryLocator factoryLocator = new JbpmFactoryLocator();
+        BeanFactoryReference factory = factoryLocator.useBeanFactory(null);
+        
+        transactionService = (TransactionService)factory.getFactory().getBean(ServiceRegistry.TRANSACTION_SERVICE.getLocalName());
+        jobLockService = (JobLockService)factory.getFactory().getBean(ServiceRegistry.JOB_LOCK_SERVICE.getLocalName());
+        
+        jbpmConfiguration = (JbpmConfiguration)factory.getFactory().getBean("jbpm_configuration");
+    }
+    
+    
     /* (non-Javadoc)
      * @see org.jbpm.job.executor.JobExecutor#startThread()
      */
diff --git a/source/java/org/alfresco/repo/workflow/jbpm/AlfrescoJobExecutorThread.java b/source/java/org/alfresco/repo/workflow/jbpm/AlfrescoJobExecutorThread.java
index 269cbf76f2..a08af1a028 100644
--- a/source/java/org/alfresco/repo/workflow/jbpm/AlfrescoJobExecutorThread.java
+++ b/source/java/org/alfresco/repo/workflow/jbpm/AlfrescoJobExecutorThread.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2005-2007 Alfresco Software Limited.
+ * Copyright (C) 2005-2009 Alfresco Software Limited.
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
@@ -28,8 +28,13 @@ import java.util.Collection;
 import java.util.Collections;
 import java.util.Date;
 
+import org.alfresco.repo.lock.LockAcquisitionException;
 import org.alfresco.repo.transaction.RetryingTransactionHelper;
 import org.alfresco.repo.transaction.RetryingTransactionHelper.RetryingTransactionCallback;
+import org.alfresco.service.namespace.NamespaceService;
+import org.alfresco.service.namespace.QName;
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
 import org.jbpm.JbpmConfiguration;
 import org.jbpm.job.Job;
 import org.jbpm.job.executor.JobExecutorThread;
@@ -38,13 +43,24 @@ import org.jbpm.job.executor.JobExecutorThread;
 /**
  * Alfresco Job Executor Thread
  * 
- * @author davidc
+ * @author davidc, janv
  */
 public class AlfrescoJobExecutorThread extends JobExecutorThread
 {
+    /** The name of the lock used to ensure that job executor does not run on more than one node at the same time. */
+    private static final QName LOCK_QNAME = QName.createQName(NamespaceService.SYSTEM_MODEL_1_0_URI,
+            "AlfrescoJbpmJobExecutor");
+    
+    private static Log logger = LogFactory.getLog(AlfrescoJobExecutorThread.class);
+    
     private AlfrescoJobExecutor alfrescoJobExecutor;
     private boolean isActive = true;
     
+    private long jbpmMaxLockTime;
+    
+    private long jobLockTTL = 0;
+    private String jobLockToken = null;
+    
     @Override
     public void setActive(boolean isActive)
     {
@@ -58,26 +74,75 @@ public class AlfrescoJobExecutorThread extends JobExecutorThread
     {
         super(name, jobExecutor, jbpmConfiguration, idleInterval, maxIdleInterval, maxLockTime, maxHistory);
         this.alfrescoJobExecutor = jobExecutor;
+        this.jbpmMaxLockTime = maxLockTime;
+        
+        this.jobLockTTL = jbpmMaxLockTime+(1000 * 60 * 10);
     }
 
+    @SuppressWarnings("unchecked")
     @Override
     protected Collection acquireJobs()
     {
-        if (!isActive)
+        Collection jobs = Collections.EMPTY_LIST;
+        
+        if ((isActive) && (! alfrescoJobExecutor.getTransactionService().isReadOnly()))
         {
-            return Collections.EMPTY_LIST;
-        }
-        else if (alfrescoJobExecutor.getTransactionService().isReadOnly())
-        {
-            return Collections.EMPTY_LIST;
-        }
-        return alfrescoJobExecutor.getTransactionService().getRetryingTransactionHelper().doInTransaction(
-            new RetryingTransactionHelper.RetryingTransactionCallback<Collection>() {
-                public Collection execute() throws Throwable
+            try
+            {
+                jobs = alfrescoJobExecutor.getTransactionService().getRetryingTransactionHelper().doInTransaction(
+                    new RetryingTransactionHelper.RetryingTransactionCallback<Collection>() {
+                        public Collection execute() throws Throwable
+                        {
+                            if (jobLockToken != null)
+                            {
+                                refreshExecutorLock(jobLockToken);
+                            }
+                            else
+                            {
+                                jobLockToken = getExecutorLock();
+                            }
+                            
+                            try
+                            {
+                                return AlfrescoJobExecutorThread.super.acquireJobs();
+                            }
+                            catch (Throwable t)
+                            {
+                                logger.error("Failed to acquire jobs");
+                                releaseExecutorLock(jobLockToken);
+                                jobLockToken = null;
+                                throw t;
+                            }
+                        }
+                });
+                
+                if (jobs != null)
                 {
-                    return AlfrescoJobExecutorThread.super.acquireJobs();
+                    if (logger.isDebugEnabled() && (! logger.isTraceEnabled()) && (! jobs.isEmpty()))
+                    {
+                        logger.debug("acquired "+jobs.size()+" job"+((jobs.size() != 1) ? "s" : ""));
+                    }
+                    
+                    if (logger.isTraceEnabled())
+                    {
+                        logger.trace("acquired "+jobs.size()+" job"+((jobs.size() != 1) ? "s" : "")+((jobs.size() > 0) ? ": "+jobs.toString() : ""));
+                    }
+                    
+                    if (jobs.size() == 0)
+                    {
+                        releaseExecutorLock(jobLockToken);
+                        jobLockToken = null;
+                    }
                 }
-            });
+            }
+            catch (LockAcquisitionException e)
+            {
+                // ignore
+                jobLockToken = null;
+            }
+        }
+        
+        return jobs;
     }
 
     @Override
@@ -87,6 +152,7 @@ public class AlfrescoJobExecutorThread extends JobExecutorThread
         {
             return null;
         }
+        
         return alfrescoJobExecutor.getTransactionService().getRetryingTransactionHelper().doInTransaction(
             new RetryingTransactionHelper.RetryingTransactionCallback<Date>() {
                 public Date execute() throws Throwable
@@ -95,24 +161,104 @@ public class AlfrescoJobExecutorThread extends JobExecutorThread
                 }
             }, true);
     }
-
+    
     /**
      * {@inheritDoc}
      */
     @Override
     protected void executeJob(Job job)
     {
-        if (!isActive)
+        if ((!isActive) || (alfrescoJobExecutor.getTransactionService().isReadOnly()))
         {
             return;
         }
-        else if (alfrescoJobExecutor.getTransactionService().isReadOnly())
+        
+        try
         {
-            return;
+            alfrescoJobExecutor.getTransactionService().getRetryingTransactionHelper().doInTransaction(new TransactionJob(job));
+        }
+        catch (LockAcquisitionException e)
+        {
+            // ignore
+            jobLockToken = null;
         }
-        alfrescoJobExecutor.getTransactionService().getRetryingTransactionHelper().doInTransaction(new TransactionJob(job));
     }
     
+    private String getExecutorLock()
+    {
+        String jobLockToken = null;
+        
+        if (alfrescoJobExecutor.getJobExecutorLockEnabled())
+        {
+            try
+            {
+                jobLockToken = alfrescoJobExecutor.getJobLockService().getLock(LOCK_QNAME, jobLockTTL, 3000, 10);
+                
+                if (logger.isTraceEnabled())
+                {
+                    logger.trace(Thread.currentThread().getName()+" got lock token: "+jobLockToken);
+                }
+            }
+            catch (LockAcquisitionException e)
+            {
+                if (logger.isTraceEnabled())
+                {
+                    logger.trace("Failed to get Alfresco Job Executor lock - may already running in another thread");
+                }
+                throw e;
+            }
+        }
+        
+        return jobLockToken;
+    }
+    
+    private void refreshExecutorLock(String jobLockToken)
+    {
+        if (jobLockToken != null)
+        {
+            try
+            {
+                alfrescoJobExecutor.getJobLockService().refreshLock(jobLockToken, LOCK_QNAME, jobLockTTL);
+                
+                if (logger.isTraceEnabled())
+                {
+                    logger.trace(Thread.currentThread().getName()+" refreshed lock token: "+jobLockToken);
+                }
+            }
+            catch (LockAcquisitionException e)
+            {
+                if (logger.isTraceEnabled())
+                {
+                    logger.trace("Failed to refresh Alfresco Job Executor lock  - may no longer exist ("+jobLockToken+")");
+                }
+                throw e;
+            }
+        }
+    }
+    
+    private void releaseExecutorLock(String jobLockToken)
+    {
+        if (jobLockToken != null)
+        {
+            try
+            {
+                alfrescoJobExecutor.getJobLockService().releaseLock(jobLockToken, LOCK_QNAME);
+                
+                if (logger.isTraceEnabled())
+                {
+                    logger.trace(Thread.currentThread().getName()+" released lock token: "+jobLockToken);
+                }
+            }
+            catch (LockAcquisitionException e)
+            {
+                if (logger.isTraceEnabled())
+                {
+                    logger.trace("Failed to release Alfresco Job Executor lock - may no longer exist ("+jobLockToken+")");
+                }
+                throw e;
+            }
+        }
+    }
     
     /**
      * Helper class for holding Job reference
@@ -122,7 +268,7 @@ public class AlfrescoJobExecutorThread extends JobExecutorThread
     private class TransactionJob implements RetryingTransactionCallback<Object>
     {
         private Job job;
-
+        
         /**
          * Constructor
          * 
@@ -132,13 +278,19 @@ public class AlfrescoJobExecutorThread extends JobExecutorThread
         {
             this.job = job;
         }
-
+        
         public Object execute() throws Throwable
         {
+            refreshExecutorLock(jobLockToken);
+            
             AlfrescoJobExecutorThread.super.executeJob(job);
+            
+            if (logger.isDebugEnabled())
+            {
+                logger.debug("executed job: "+job);
+            }
+            
             return null;
         }
-
     }
-        
 }