[pysqlite] database locked

Lately I've been getting "database lock" error exception in my application.  It 
usually happens when the system is under heavy load.  From what I've read, this 
error message shows up whenever a transaction times out.  In my environment, 
timeout is not option, I need to keep retrying until I succeed.  What's the best 
way to work around "database locks" exceptions?  I tried increasing the timeout 
value to something like 500 seconds but I still keep getting the exception.