程序包调用报ORA-06508: PL/SQL: 无法找到正在调用的程序单元

背景：

开发人员修改一个包里一个过程，修改成功，并重新编译成功，在程序日志发现调用这个包报错ORA-06508: PL/SQL: 无法找到正在调用的程序单元

-----会话1：

CREATE OR REPLACE PACKAGE SimplePkg AS  
   v_GlobalVar1 NUMBER := 1;  
   PROCEDURE UpdateVar;   
END SimplePkg;  
/
CREATE OR REPLACE PACKAGE BODY SimplePkg AS   
   PROCEDURE UpdateVar IS  
   vv number;
   xx number;
   BEGIN  
      v_GlobalVar1 := 7;   
   END UpdateVar;  
END SimplePkg;  
/

set line 300
col object_name for a30
 alter session set nls_date_format = 'yyyy-mm-dd hh24:mi:ss';
SELECT owner, object_type, object_name, status,created,last_ddl_time
     FROM all_objects
    WHERE 
       object_name in (SELECT name FROM dba_dependencies WHERE OWNER = 'TEST' AND referenced_name='SIMPLEPKG' )
       --AND status = 'INVALID'
     ORDER BY OWNER;


OWNER                          OBJECT_TYPE         OBJECT_NAME                    STATUS  CREATED             LAST_DDL_TIME
------------------------------ ------------------- ------------------------------ ------- ------------------- -------------------
TEST                             PACKAGE BODY        SIMPLEPKG                      VALID   2022-03-01 18:33:21 2022-03-01 18:33:21
TEST                             PACKAGE             SIMPLEPKG                      VALID   2022-03-01 18:33:16 2022-03-01 18:33:16

-----会话2：

BEGIN   
   simplePkg.UpdateVar;   
END;  /

-----会话1：

CREATE OR REPLACE PACKAGE BODY SimplePkg AS   
   PROCEDURE UpdateVar IS  
   vv number;
   xx number;
   yy  number;
   BEGIN  
      v_GlobalVar1 := 7;   
   END UpdateVar;  
END SimplePkg;  
/


set line 300
col object_name for a30
 alter session set nls_date_format = 'yyyy-mm-dd hh24:mi:ss';
SELECT owner, object_type, object_name, status,created,last_ddl_time
     FROM all_objects
    WHERE 
       object_name in (SELECT name FROM dba_dependencies WHERE OWNER = 'TEST' AND referenced_name='SIMPLEPKG' )
       --AND status = 'INVALID'
     ORDER BY OWNER;



OWNER                          OBJECT_TYPE         OBJECT_NAME                    STATUS  CREATED             LAST_DDL_TIME
------------------------------ ------------------- ------------------------------ ------- ------------------- -------------------
TEST                             PACKAGE BODY        SIMPLEPKG                      VALID   2022-03-01 18:33:21 2022-03-01 18:39:29
TEST                             PACKAGE             SIMPLEPKG                      VALID   2022-03-01 18:33:16 2022-03-01 18:33:16

-----会话2：

SQL>  BEGIN   
   simplePkg.UpdateVar;   
END; 
    /
 BEGIN
*
ERROR at line 1:
ORA-04068: existing state of packages has been discarded
ORA-04061: existing state of package body "TEST.SIMPLEPKG" has been invalidated
ORA-04065: not executed, altered or dropped package body "TEST.SIMPLEPKG"
ORA-06508: PL/SQL: could not find program unit being called: "TEST.SIMPLEPKG"
ORA-06512: at line 2

原因：

出现这种情况的原因是因为，对于全局变量，每一个session会生成一个本地copy，如果程序重新编译的话，就会因程序里原变量找不到而丢弃该变量，继而导致这个错误。
也就是说在一个会话中调用程序包package时，会生成package中全局变量的副本，如果在另一个会话中对此package进行编译就会使前一个会话中的副本失效，故而产生错误。

处理：

要想避免这个错误，可以使程序捕获ORA-06508:的错误进行处理，也可以重新初始化会话