Hi! What is your database connection url? It looks like you have more processes running and trying to access database. I'd try to restart database and server as well.
connection URL is as follow:
and no other processes are involving with the database.
Well it's likely wrong. See e.g http://hsqldb.org/doc/guide/dbproperties-chapt.html. IMO it should be something like:
I did it. same error still exist. weird!
Are you able to connect to your database using some client like sqlworkbench, sqldeveloper or similar? Are there your entities you would like to create by reverse engineering? If yes, then it should also work from JBoss Tools.