ORA-12516 TNS listener could not find available handler

Question

My error   java sql SQLException  Listener refused the connection with the following error   ORA-12516  TNS listener could not find available handler with matching protocol stack The Connection descriptor used by the client was    10 2 5 21 9001 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  lt init gt  PhysicalConnection java  414          at oracle jdbc driver T4CConnection  lt init gt  T4CConnection java 165          at oracle jdbc driver T4CDriverExtension getConnection T4CDriverExtensio n java 35          at oracle jdbc driver OracleDriver connect OracleDriver java 801          at oracle jdbc pool OracleDataSource getPhysicalConnection OracleDataSou rce java 297          at oracle jdbc pool OracleDataSource getConnection OracleDataSource java  221          at oracle jdbc pool OracleDataSource getConnection OracleDataSource java  165          at utilityService DB util setOracleConnectionActive DB util java 99          at utilityService DB util getRecPreparedAuthentication DB util java 124    My common db connection class   package utilityService   import java sql CallableStatement  import java sql Connection  import java sql PreparedStatement  import java sql ResultSet  import java sql SQLException  import java sql Statement   import oracle jdbc pool OracleDataSource    public class DB util       String propValue           ResultSet rec   null      Statement stm   null      PreparedStatement pre stm   null      CallableStatement call stm   null      Connection conn1   null                  Constructure to get oracle connection             public DB util              Util util new Util            propValue util getFilePathToSave              propValue   Util propValue    get oracle connection         setOracleConnectionActive                          Close all oracle connections and result sets              public void setOracleConnectionClose             try               if  conn1    null     conn1 isClosed                      if  rec    null                        rec close                        rec   null                                    if  stm    null                        stm close                        stm   null                                    if  pre stm    null                        pre stm close                        pre stm   null                                    if  call stm    null                        call stm close                        call stm   null                                    conn1 commit                    conn1 close                    conn1   null                          catch  Exception ex                ex printStackTrace                                    return a result set according to sql sent                 param SQL         return             public ResultSet getRec String SQL            try               setOracleConnectionActive                stm   conn1 createStatement                rec   stm executeQuery SQL                return rec            catch  Exception ex                ex printStackTrace                return rec                                   Activate oracle connection             private void setOracleConnectionActive             try               if  conn1    null    conn1 isClosed                      OracleDataSource ods   new OracleDataSource                    if  propValue    null                        ods setURL propValue                                     conn1   ods getConnection                    System out println  DB connection CONNECTED                          conn1 setAutoCommit false                           catch  Exception ex                  setOracleConnectionActive                ex printStackTrace                System out println  DB connection FAILED                                          send prepared result set with user authenticate                 param SQL         param strInputUserMobile         param strInputUserName         param strInputUserPassword         return             public ResultSet getRecPreparedAuthentication String SQL              String strInputUserMobile  String strInputUserName              String strInputUserPassword             try               setOracleConnectionActive                pre stm   conn1 prepareStatement SQL               pre stm setString 1  strInputUserMobile               pre stm setString 2  strInputUserName               pre stm setString 3  strInputUserPassword               rec   pre stm executeQuery                 return rec            catch  Exception ex                ex printStackTrace                return rec                                   insert sql to db which is send as a sql                 param SQL         return             public int insertSQL String SQL            int output   0          try               setOracleConnectionActive                stm   conn1 createStatement                output   stm executeUpdate SQL               conn1 commit                output   1             catch  Exception ex                try                   conn1 rollback                    output   0                catch  SQLException e                    e printStackTrace                    output   0                            ex printStackTrace                       return output                         Send a callable statement according to sent sql                 param SQL         return             public CallableStatement callableStatementSQL String SQL             int output   0          try               setOracleConnectionActive                call stm   conn1 prepareCall SQL              catch  Exception ex                try                   conn1 rollback                    output   0                catch  SQLException e                    e printStackTrace                    output   0                            ex printStackTrace                       return call stm              Every transaction I refer this class and do my fetching  amp  CRUD operations  Is there any issue with my code

User · Answer

I fixed this problem with sql command line   connect system  lt password gt  alter system set processes 300 scope spfile  alter system set sessions 300 scope spfile    Restart database

User · Answer

You opened a lot of connections and that s the issue  I think in your code  you did not close the opened connection   A database bounce could temporarily solve  but will re-appear when you do consecutive execution  Also  it should be verified the number of concurrent connections to the database  If maximum DB processes parameter has been reached this is a common symptom    Courtesy of this thread  https   community oracle com thread 362226 tstart -1

[java] ORA-12516, TNS:listener could not find available handler

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