¿Cómo cierro a la fuerza una conexión de un grupo de conexiones cuando está tardando demasiado en cerrarse?

Función principal:

  String g_sid = "";

Hilo 1:

  String sql = ...;
  Connection conn = ...your connection func...;

  Statement stmt = conn.createStatement();
  ResultSet rset = stmt.executeQuery( "SELECT sid from v$mystat");
  if (rset.next()) g_sid = rset.getString("sid");
  rset.close();
  // now to the actual long-running SQL
  ResultSet rset = stmt.executeQuery( sql );
  // 
  stmt.close();

Hilo 2:

  String serialN = "";
  Connection conn = ...your admin connection func...

  Statement stmt = conn.createStatement();
  ResultSet rset = stmt.executeQuery( "SELECT serial# serialN from v$session where sid=" + g_sid );
  if (rset.next()) {
    serialN = rset.getString("serialN"); 
    stmt.execute("alter system kill session '" + g_sid + "," + serialN + "'");
  }
  stmt.close();
  // probably keep the admin connection open for further maintenance
  //