Intermittent ORA-12519 error on 10g XE

There’s an Oracle error that seems to raise its ugly head every now and again and it occurs on Oracle 10g Express Edition running under 32 bit Windows (which in my case was XP). It happened to me after transferring my test Oracle database from a real to a virtual copy of Windows XP, and when running a series of unit tests on a database module.

The error manifests itself as an ORA-12519 connection refusal error as highlighted by the following partial stack trace:

java.sql.SQLException: Listener refused the connection with the following error:
ORA-12519, TNS:no appropriate service handler found
The Connection descriptor used by the client was:
junit:1521:xe
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:112)
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:261)
at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:387)
at oracle.jdbc.driver.PhysicalConnection.(PhysicalConnection.java:414)

The suggested fix, and this was written two years ago, is to increase the number of available processes by logging on as SYS and issuing the following command:

ALTER SYSTEM SET PROCESSES=150 SCOPE=SPFILE

…which doesn’t seem like a real fix to me as it just pushes the problem further away.

Yes, I know that Oracle 10g is obsolete and the 11g Express Edition is freely available, but 11g adds yet another layer of unwanted complexity to my requirement for a simple Oracle database.