Index: lams_tool_scratchie/src/java/org/lamsfoundation/lams/tool/scratchie/web/action/LearningAction.java
===================================================================
diff -u -r28e0c7b1e1c001a249f208dbd45343fedc0c60fa -r93b287bd36a1b86048c7ac2d6da72d5ef461bff6
--- lams_tool_scratchie/src/java/org/lamsfoundation/lams/tool/scratchie/web/action/LearningAction.java	(.../LearningAction.java)	(revision 28e0c7b1e1c001a249f208dbd45343fedc0c60fa)
+++ lams_tool_scratchie/src/java/org/lamsfoundation/lams/tool/scratchie/web/action/LearningAction.java	(.../LearningAction.java)	(revision 93b287bd36a1b86048c7ac2d6da72d5ef461bff6)
@@ -47,6 +47,7 @@
 import org.apache.struts.action.ActionRedirect;
 import org.apache.tomcat.util.json.JSONException;
 import org.apache.tomcat.util.json.JSONObject;
+import org.hibernate.exception.LockAcquisitionException;
 import org.lamsfoundation.lams.learning.web.bean.ActivityPositionDTO;
 import org.lamsfoundation.lams.learning.web.util.LearningWebUtil;
 import org.lamsfoundation.lams.notebook.model.NotebookEntry;
@@ -439,14 +440,33 @@
 
 	String nextActivityUrl = null;
 	try {
-	    nextActivityUrl = service.finishToolSession(toolSessionId, user.getUserID().longValue());
+	    nextActivityUrl = finishToolSession(toolSessionId, user.getUserID().longValue());
 	    request.setAttribute(ScratchieConstants.ATTR_NEXT_ACTIVITY_URL, nextActivityUrl);
 	} catch (ScratchieApplicationException e) {
 	    LearningAction.log.error("Failed get next activity url:" + e.getMessage());
 	}
 
 	return mapping.findForward(ScratchieConstants.SUCCESS);
     }
+    
+    public String finishToolSession(Long toolSessionId, Long userId) throws ScratchieApplicationException {
+	final int MAX_TRANSACTION_RETRIES = 5;
+	String nextActivityUrl = null;
+	for (int i = 0; i < MAX_TRANSACTION_RETRIES; i++) {
+	    try {
+		nextActivityUrl = service.finishToolSession(toolSessionId, userId);;
+		break;
+	    } catch (LockAcquisitionException e) {
+		if (i == MAX_TRANSACTION_RETRIES - 1) {
+		    throw new ScratchieApplicationException(e);
+		}
+	    } catch (Exception e) {
+		throw new ScratchieApplicationException(e);
+	    }
+	    log.warn("Transaction retry: " + (i + 1));
+	}
+	return nextActivityUrl;
+    }
 
     /**
      * Display empty reflection form.