Implicit PL/SQL cursors remain open, causing ORA-01000 (Client 9.2.0.1)

Question

Hello,
since migrating our system from Oracle Client 9.0.X to 9.2.0.1 (Windows XP), i am encountering troubles when calling a stored procedure from a Cobol-Program:
after a while i run into a 'Maximum open cursors exceeded'-message (ORA-01000)
The stored procedure returns a cursor (ref_cursor)
When Executing the stored procedure, there are actually 2 cursors involved, in fact the stored PL/SQL procedure implicitely opens a child-cursor when doing a select within the PL/SQL.
After fetching the result and closing the cursor in my cobol-program, it correctly closes the cursor associated with the stored-procedure, but it does not close the cursor that was implicitely opened by oracle.
After a while i am running into a Maximum open cursors message, because those cursors have not properly been closed.
Here's a simple PL/SQL package that illustrates the problem:
create or replace package scott.SCOTTS_PACKAGE is
type ref_cursor IS REF CURSOR;
function GET_EMP(EMP_IN CHAR) return ref_cursor;
end SCOTTS_PACKAGE;
create or replace package body scott.SCOTTS_PACKAGE is
-- Function and procedure implementations
function GET_EMP(EMP_IN CHAR) return ref_cursor is
MyCurs ref_cursor;
begin
OPEN MyCurs FOR
SELECT EMPNO ,
ENAME ,
JOB
FROM SCOTT.EMP
WHERE ENAME = EMP_IN;
return(MyCurs);
end;
end SCOTTS_PACKAGE;
Here are some exerpts from my cobol program:
(The program iterates 100x through the section that executes the PL/SQL. After each iteration an additional open cursor remains in the database)
003800 EXEC SQL BEGIN DECLARE SECTION END-EXEC.
003900*
004000 01 SQL-USERNAME PIC X(16) VARYING.
004100 01 SQL-PASSWD PIC X(16) VARYING.
004200 01 SQL-DBNAME PIC X(64) VARYING.
004300 01 ORACLE.
004700 02 ORA-CUR-EMP SQL-CURSOR.
01 EMPREC.
02 EMPREC-EMPNO PIC X(4).
02 EMPREC-ENAME PIC X(10).
02 EMPREC-JOB PIC X(9).
005400 EXEC SQL END DECLARE SECTION END-EXEC.
018400 PROCEDURE DIVISION.
CONTINUE.
018700 EXEC SQL
018800 WHENEVER SQLERROR DO PERFORM SQL-ERROR
018900 END-EXEC.
019000*
CONTINUE.
019100 EXEC SQL
019200 WHENEVER NOT FOUND DO PERFORM SQL-NOT-FOUND
019300 END-EXEC.
022400 EXEC SQL
022500 ALLOCATE :ORA-CUR-EMP
022600 END-EXEC
PERFORM VARYING I FROM 1 BY 1 UNTIL I > 100
ACCEPT DUMMY FROM TER
IF DUMMY = "E"
MOVE 100 TO I
END-IF
PERFORM GET-EMP
ADD 1 TO I
END-PERFORM
119300 GET-EMP SECTION.
119400************************
119500 GAM0.
MOVE SPACES TO EMPREC-EMPNO EMPREC-JOB
MOVE "SMITH" TO EMPREC-ENAME
120200 EXEC SQL AT SSSI EXECUTE
120300 BEGIN
120400 :ORA-CUR-EMP:=
120500 SCOTT.SCOTTS_PACKAGE.GET_EMP(:EMPREC-ENAME );
120900
END;
121000 END-EXEC
121200 IF DB-ERR-CODE NOT = HIGH-VALUE
121300 DISPLAY "CCSIFSO:GET-AUTRE-MATR:APPEL PERS... OK"
121400 EXEC SQL
121500 FETCH :ORA-CUR-EMP
121600 INTO
121700 :EMPREC-EMPNO,
121800 :EMPREC-ENAME,
121900 :EMPREC-JOB
122400 END-EXEC
122500 END-IF
122600*
122700 IF DB-ERR-CODE NOT = HIGH-VALUE
122800 DISPLAY "CCSIFSO:GET-AUTRE-MATR:APPEL FETCH.. OK"
123000 ELSE
123100 MOVE LOW-VALUE TO DB-ERR-CODE
123200 END-IF
123300 EXEC SQL
123400 CLOSE :ORA-CUR-EMP
123500 END-EXEC
123600 GA-EX.
123700 EXIT.
124000 SQL-NOT-FOUND SECTION.
124100*----------------------
124200 NF0.
124300 DISPLAY "CCSIFSO:SQL-NOT-FOUND SECTION."
124400 MOVE HIGH-VALUE TO DB-ERR-CODE.
124500 NF-EX.
124600 EXIT.
124700*
124800 SQL-ERROR SECTION.
124900*-----------------
125000 ER0.
125200 EXEC SQL
125300 WHENEVER SQLERROR CONTINUE
125400 END-EXEC
125700 MOVE HIGH-VALUE TO DB-ERR-CODE
125800*
126100 DISPLAY "ORACLE ERROR DETECTED: " SQLCODE UPON TER
126200 DISPLAY SQLERRMC UPON TER
126300*
126400 EXEC SQL AT SSSI
126500 ROLLBACK WORK
126600 RELEASE
126700 END-EXEC
126800 DISPLAY "----------------------------" UPON TER
126900 DISPLAY " ! ROLLBACK ET DISCONNECT ! " UPON TER
127000 DISPLAY "----------------------------" UPON TER
127200 CALL "PPTERMJ".
127400 ER-EX.
127500 EXIT.
Finally here's an exerpt from V$OPEN_CURSOR, after a few iterations:
1 begin :b1 := SCOTT . SCOTTS_PACKAGE . GET_EMP (:b2 ) ; END ;
2 SELECT EMPNO , ENAME , JOB FROM EMP WHERE ENAME = :B1
3 SELECT EMPNO , ENAME , JOB FROM EMP WHERE ENAME = :B1
4 SELECT EMPNO , ENAME , JOB FROM EMP WHERE ENAME = :B1
5 SELECT EMPNO , ENAME , JOB FROM EMP WHERE ENAME = :B1
6 SELECT EMPNO , ENAME , JOB FROM EMP WHERE ENAME = :B1
7 SELECT EMPNO , ENAME , JOB FROM EMP WHERE ENAME = :B1
8 SELECT EMPNO , ENAME , JOB FROM EMP WHERE ENAME = :B1
9 SELECT EMPNO , ENAME , JOB FROM EMP WHERE ENAME = :B1
10 SELECT EMPNO , ENAME , JOB FROM EMP WHERE ENAME = :B1
11 SELECT EMPNO , ENAME , JOB FROM EMP WHERE ENAME = :B1
As you see, there is only 1 cursor starting with 'begin ... '
but there are 10 implicit cursors 'SELECT EMPNO, ... ' that have not been properly closed, nor reused by ORACLE.
In our old configuration (ORACLE CLient 9.0.X), you would only see:
1 begin :b1 := SCOTT . SCOTTS_PACKAGE . GET_EMP (:b2 ) ; END ;
2 SELECT EMPNO , ENAME , JOB FROM EMP WHERE ENAME = :B1
meaning all the other cursors have properly been closed.
As a conclusion: the program correctly closes the implicit cursors when using a 9.0 Client, wheras the implicit cursors remain open on Client 9.2.0.1 (Windows XP)
The underlying database can be either 8.i or 9, the problem remains the same.
Finally here's a small Delphi code, using ODAC-components, that somewhat illustrates the same problem:
procedure TForm1.ExecProcClick(Sender: TObject);
var I: INTEGER ;
begin
FOR I := 1 TO 5 DO
BEGIN
SP1.StoredProcName:='SCOTT.SCOTTS_PACKAGE.GET_EMP';
SP1.Prepare;
SP1.ParamByName('EMP_IN').AsString := 'SMITH';
SP1.ExecProc;
SP1.Next;
SP1.Close;
SP1.UnPrepare;
END;
end;
After each call to 'PREPARE', an additional implicit cursor remains open on the database. (using Oracle Client 9.2.0.1)
On our old system (Oracle Client 9.0 or 8.X), the same program would not generate accumulating open cursors on the database
Any suggestions would be welcome,
Claude

Answer 1

Cobol.. been many years since I last even saw some Cobol source code. Invokes all kinds of memories. :-)
Since you found the patch, the advice is superfluous, but works. Close the cursor at the PL/SQL side, e.g.
create or replace procedure CloseRefCursor( cRefCursor TYPELIB.TRefCursor ) is
begin
  close cRefCursor;
exception when OTHERS then
  -- if the cursor is already gone, not a problem
  NULL;
end;In Delphi for example, one can subclass the class used for ref cursor calls and add a call to the above PL/SQL proc in the destructor. Or add create a standard Cobol close ref cursor section that does similar.