Lock time out; try later.: Why it occurs

Question

Hi ,
I m trying Insert_update_delete tutorial with my tables
when i create Page2.jsp with Update buttons on Page1.jsp when i deploy it it gives me followin exception .
No errors are there in bean files how do i Trace it?
CAN ANYBODY HELP COMING OUT OF THIS????
Description: An unhandled exception occurred during the execution of the web application. Please review the following stack trace for more information regarding the error.
Exception Details: javax.faces.el.EvaluationException
javax.faces.FacesException: javax.faces.FacesException: Can't instantiate class: 'signon.Page1'.. class signon.Page1 : javax.faces.FacesException: java.sql.SQLException: Lock time out; try later.
Possible Source of Error:
Class Name: com.sun.faces.el.ValueBindingImpl
File Name: ValueBindingImpl.java
Method Name: getValue
Line Number: 206
Source not available. Information regarding the location of the exception can be identified using the exception stack trace below.
Regards !!!!!!
Priya

Answer 1

Hi Priya,
There are a few reasons this kind of error can occur - typically it's because a rowset didn't get closed for some reason. If you're using pointbase, this can happen pretty easily because the number of connections that are supported is very low etc. Check your server.log file to see if there is any additional information - the error stack presented in the browser sometimes doesn't hold all the information. It's difficult to diagnose with just the information you have provided here. I can't tell if it's a table that's locked or the entire db.
If this problem is occuring in Pointbase during your development, the way to clean it up is to restart pointbase and the appserver.
A few scenarios where this problem can occur (yours might be the first one):
1) could be an issue w/inserts... we are thinking we might want to revise the tutorial here... instead of :
  rowset.execute();
  rowset.moveToInsertRow();
  rowset.updateObject("FOO", new Integer(0));
  rowset.updateObject("ID", getNextId());try instead constructing the insert manually, something like:
Context ctx = new InitialContext();
DataSource ds = (DataSource)ctx.lookup(blahblahrowset.getDataSourceName());
Connection c = ds.getConnection();
c.setAutoCommit(false);
Statement stmt = c.createStatement();
int count = stmt.executeUpdate("INSERT INTO person (PersonID, Name, JobTitle) VALUES ((SELECT (MAX(PersonID)+1) from Person), 'The New Guy', 'new guy title')");
// you can verify count is 1 here, but really its not necessary as a SQLException will be thrown if something went wrong - just make sure you close in the exception handler as well
stmt.close();
c.commit();
c.close(); Also note that "getNextPK" approach in the tutorial is just a quick and dirty approach - you should probably use identity columns or perhaps the MAX approach shown in the code above... if you do use an identity column, you would remove the id column from the insert statement and let the db handle it.
2) An exception is thrown in your application and therefore it is skipping the afterRenderResponse method which contains the close statement
Solution: Avoid throwing exceptions - and if you must throw an exception, make sure to close the rowset before throwing.
3) If you put a rowset in the session or application bean, you might be holding a lock on the table somewhere
Solution: Avoid putting rowsets in Session and application beans - if you must access the database in those beans, close the rowsets as soon as possible - ideally don't just leave them open. If you must hold them open for extended periods of time. be aware that your pages may not be able to access those tables via direct binding.