Re: MySQL deadlock exceptions

[Ramiro Aparicio]

El 05/08/2014 15:54, Andrus Adamchik escribió:
After years working with MySQL I stumbled on a problem for the first time that 
seems rather old and common. MySQL would throw when 2 InnoDB transactions are 
trying to update the same row:
com.mysql.jdbc.exceptions.jdbc4.MySQLTransactionRollbackException: Deadlock 
found when trying to get lock; try restarting transaction

I am wondering whether we should add a “catch/restart tx” to Cayenne to handle 
that. The purpose of this message is to ask how often if ever folks in the 
community have to deal with this exception?

Thanks,
Andrus



I have been seen that error for a while, we use an abstract Dao 
inherited by all daos so all commits use this funcion:

        public void commitChanges() {
            this.commitChanges(0);
        }

        public void commitChanges(int level) {
            try {
                getThreadDataContext().commitChanges();
            } catch (RuntimeException cre) {
                if (level < 3 &&
                        (cre.getCause() instanceof
   MySQLTransactionRollbackException
                        || cre.getCause() instanceof
   com.mysql.jdbc.exceptions.MySQLTransactionRollbackException)) {
                    commitChanges(level+1);
                } else {
                    CayenneCommitException cce = new
   CayenneCommitException(cre, getThreadDataContext());
                    rollbackChanges();
                    throw cce;
                }
            }
        }


Not sure if this helps or not but currently we only see like 1 of those 
errors per month and I think that previously it was more frequent.