I'm using Spring transactions with eclipselink in tomcat, mysql enviornment.
I was getting lock timeout issues always when testing my web application and i was looking for issues with Spring transactions with eclipselink, but finally got my doubt cleared with the log statements.
You can increase your sequence pre-allocation size to reduce the contention on the sequence table. You can also have each of your classes use a different sequence name, or even different sequence table (to prevent page locks).
Are you getting a deadlock, or just contention?
Ensure that you are using a sequence connection pool so that sequence values are allocated outside of the current transaction.
Are you using JTA? if so ensure you also set a nonJtaDataSource