Script to generate Kill Locked Sessions in Oracle :

In case of RDS ,

SELECT 'exec rdsadmin.rdsadmin_util.kill('||s.sid ||','|| s.serial# ||' );'
FROM v$session s ,
v$process p ,
v$lock l ,
dba_objects o
WHERE
s.paddr = p.addr
AND l.sid = s.sid
AND l.id1 = o.object_id
AND s.username = 'XXAPPS' --- Change as needed.
AND object_name like ('XXSC%'); --- Change as needed.

When you try to Open R12 Form template fmb files in Oracle forms, you may receive FRM-10102: Cannot attach PL/SQL library APPCORE .

Unable to open Template.fmb. Getting following error

FRM-10102: Cannot attach PL/SQL library APPCORE. This library attachment will be lost if the module is saved.
FRM-10102: Cannot attach PL/SQL library APPDAYPK. This library attachment will be lost if the module is saved.
FRM-10102: Cannot attach PL/SQL library GLOBE. This library attachment will be lost if the module is saved.
FRM-10102: Cannot attach PL/SQL library FNDSQF. This library attachment will be lost if the module is saved.
FRM-10102: Cannot attach PL/SQL library JA. This library attachment will be lost if the module is saved.
FRM-10102: Cannot attach PL/SQL library JE. This library attachment will be lost if the module is saved.
FRM-10102: Cannot attach PL/SQL library JL. This library attachment will be lost if the module is saved.
FRM-10102: Cannot attach PL/SQL library VERT. This library attachment will be lost if the module is saved.
FRM-10102: Cannot attach PL/SQL library GHR. This library attachment will be lost if the module is saved.
FRM-10102: Cannot attach PL/SQL library PQH_GEN. This library attachment will be lost if the module is saved.
FRM-10102: Cannot attach PL/SQL library PSAC. This library attachment will be lost if the module is saved.

Solution : Set the Path for FORMS_PATH with the location of all core libraries(pll files).

Dynamic Performance Views

Oracle contains a set of underlying views that are maintained by the database server and accessible to the database administrator user SYS. These views are called dynamic performance views because they are continuously updated while a database is open and in use, and their contents relate primarily to performance.

Although these views appear to be regular database tables, they are not. These views provide data on internal disk structures and memory structures. You can select from these views, but you can never update or alter them.

https://docs.oracle.com/cd/B28359_01/server.111/b28320/dynviews_1001.htm#i1398692

There are two types of views,  

• V$ Views
• GV$ Views

Almost For Every V$ View there is a GV$View which will hold the instance specific Information in a Multi Instance Environment like RAC.

These Dynamic Views are owned by Sys User and These views are constructed based on the Oracle Internal Memory Structures (X$ Tables/Views). We cannot alter or Update on these views. These X$ structure Get Created when the Instance started and Will get destroyed when you shutdown the DB.  

V$FIXED_VIEW

V$FIXED_TABLE displays all dynamic performance tables, views, and derived tables in the database.

V$FIXED_VIEW_DEFINITION

This  View contains the definitions of all the fixed views (views beginning with V$). Use this table with caution. Oracle tries to keep the behavior of fixed views the same from release to release, but the definitions of the fixed views can change without notice.

As described in the Above Example, Dynamic Performance views are based on Internal Memory Structures X$.

The X$ tables/views  are platform-specific & the No of tables are keep on increasing By Oracle Version.The Oracle kernel consists of layers. The X$ table names contain an abbreviation for the particular kernel layer.

The No#  Of Views are dependent on Oracle version and the OS Specific.

These Views Get populated only when the Instance Started. These Views Contains information about all the parameters,performance etc info. As We all know Oracle has documented some of Dynamic Views (V$_ objects) which are in handy to get the info from your instance these Dynamic Views are Based on GV$_ VIEWS which includes the data for Multiple Instances.  GV$ are Designed from these Fixed Views. View Columns might be similar from version to version where as Underlying Fixed X$ objects might different.

Why do we call them “Fixed”?

As mentioned, All these Objects are owned by SYS and DDL or DML Operations are not permitted/supported on these. Even if we try to perform, Operation will end up with error ORA-02030: can only select from fixed tables/views.

These objects contain information about the current configuration of the instance, information about the sessions connected to the instance, and a goldmine of performance information.  

Using Views like (g) v$fixed_view_definition  one can get the Actual Creation script of these Fixed views which are harmful in case of replacing the Existing or Create New views, which will end up with Errors or incorrect data as These Views are for Oracle not for Others. DBA/Developers should not create Objects using actual “V$_ “, they need to use v$ Objects instead of v$_ or X$, as The Definition of the base view may change in OS/DB software versions.   

The X$ views are completely undocumented, and Oracle does not provide any assistance for deriving the meaning of the contents of the X$ structures. since V$ views are dynamic and consistency is not guaranteed, Oracle does not support joins or sorts of dynamic views.  

The X$ views are an Oracle internal interface not exposed for customer use; customers should not be using it unless directed to do so by the support.Customer use without support guidance is unsupported.

https://blogs.oracle.com/stevenchan/oracle-e-business-suite-1227-now-available

When you have Discoverer and EBS running on the same machine, this kind of conflicts may happen.

To resolve,
Start another session, clear All Environment Variables, restart the Web-logic Server Again. 

This will resolve the issue. For More Info, Refer

There was an error while Re-Starting Our Newly Configured Oracle R12.2.6 Application Instance after a Hard reboot. I was unable to start some of the Server Components like oacore, oafm and forms.   When I tried to start them Manually, There was No error and everything seems to be started Successfully, But I was unable to access the URL with Below Error.

” Error 404–Not Found From RFC 2068 Hypertext Transfer Protocol — HTTP/1.1: 10.4.5 404 Not Found The server has not found anything matching the Request-URI. No indication is given of whether the condition is temporary or permanent. If the server does not wish to make this information available to the client, the status code 403 (Forbidden) can be used instead. The 410 (Gone) status code SHOULD be used if the server knows, through some internally configurable mechanism, that an old resource is permanently unavailable and has no forwarding address. ”

This  is due to the failure of  oafm_server,Forms_server and oacore_server using EBS Startup scripts .Starting Using Web Logic Server Deployments as  below endup with Java Null Pointer Issues with state as”ADMIN”

“<Server ‘forms_server1’ in cluster ‘forms_cluster1′ is being brought up in administration state due to failed deployments.>

“(self-tuning)’> <<WLS Kernel>> <> <> <1417622780708> <BEA-149205> <Failed to initialize the application ‘oafm [Version=1.0.0]’ due to error java.lang.NullPointerException.
java.lang.NullPointerException
at java.io.File.<init>(File.java:251)
at oracle.apps.ad.util.AppStartupPropertyListener.preStart(AppStartupPropertyListener.java:89)
at weblogic.application.internal.flow.BaseLifecycleFlow$PreStartAction.run(BaseLifecycleFlow.java:290) ”

This is Due to the recent Change in Hosts file. My Database Lister Started with an Alias Name defined in the Host file and these Server Components were unable to start/connect to the Actual Host Defined.   Changing the Host Entry and restart of these Components  resolved the issue.

For More info Refer Below Oracle Metalink Document

http://www.careers.tcs.com/CareersDesign/Jsps/OracleDrive/AboutTCS.html