By default, when we return a JDBC connection to the pool we execute the following in the ManagedConnection.cleanup() method:

if (jdbcTransactionIsolation != transactionIsolation)
{
try

{ con.setTransactionIsolation(jdbcTransactionIsolation); jdbcTransactionIsolation = transactionIsolation; }

catch (SQLException e)

{ mcf.log.warn("Error resetting transaction isolation ", e); }

}

In this scenario we don't return the original isolation level on the underlying connection. The spec doesn't prohibit this, and I can't see any reason why we shouldn't do this, or provide a configurable option.